[Elecraft] K3 PSK31 transmit at what power out?
Ian Kahn
nv4c.ian at gmail.com
Wed Jan 20 12:41:22 EST 2021
I used to run PSK31 on my K3 at 25-30 watts with no issues, no breaks
needed.
Ian, NV4C
On Wed, Jan 20, 2021, 11:35 AM John McBride <jlm124 at outlook.com> wrote:
> My K3 is working well on PSK31, but I have seen some information about
> operating digital at 25 watts. Presently I transmit at 25 watts with great
> success. The comments are that at that low power the fan may not keep the
> equipment cool enough. One suggestion was to transmit at a higher power,
> and another was to schedule a break every few minutes to allow the rig to
> cool. I will appreciate you sharing any information or experience you have.
> I am getting ready for Winter Field Day and hope to make many PSK31
> contacts.
>
> ________________________________
> From: elecraft-bounces at mailman.qth.net <elecraft-bounces at mailman.qth.net>
> on behalf of elecraft-request at mailman.qth.net <
> elecraft-request at mailman.qth.net>
> Sent: Tuesday, January 19, 2021 5:56 PM
> To: elecraft at mailman.qth.net <elecraft at mailman.qth.net>
> Subject: Elecraft Digest, Vol 201, Issue 26
>
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> Today's Topics:
>
> 1. Re: K4 Receive Filter question (David Box)
> 2. Re: K4 Receive Filter question (George Thornton)
> 3. Re: K4 Receive Filter question (Louandzip)
> 4. Re: K4 Receive Filter question (Wes)
> 5. Re: Efficiency of MFJ remotely-tuned loop antennas (Fred Jensen)
> 6. Absurd remarks about FCC and ARRL notices. (Joseph Shuman)
> 7. Re: Absurd remarks about FCC and ARRL notices. (kennedyjp)
> 8. Re: Absurd remarks about FCC and ARRL notices. (Al London)
> 9. Re: Absurd remarks about FCC and ARRL notices. (Wayne Burdick)
> 10. Something different, old memories and using the KX3 (Paul GACEK)
> 11. Re: Something different, old memories and using the KX3
> (Dave Sublette)
> 12. Re: Absurd remarks about FCC and ARRL notices. (hbjr at optilink.us)
> 13. Re: Efficiency of MFJ remotely-tuned loop antennas (Alan Bloom)
> 14. Re: Efficiency of MFJ remotely-tuned loop antennas (Louandzip)
> 15. Re: Absurd remarks about FCC and ARRL notices. (Barry)
> 16. Re: Efficiency of MFJ remotely-tuned loop antennas (Eric Garner)
>
>
> ----------------------------------------------------------------------
>
> Message: 1
> Date: Tue, 19 Jan 2021 12:51:52 -0600
> From: David Box <dobox at suddenlink.net>
> To: elecraft at mailman.qth.net
> Subject: Re: [Elecraft] K4 Receive Filter question
> Message-ID: <8046aaba-68e7-1624-2902-6a37718c45b5 at suddenlink.net>
> Content-Type: text/plain; charset=utf-8; format=flowed
>
> Bruce,
>
> Below are the receiver sensitivity specs from page 42 of the recently
> updated manual
>
>
> Sensitivity??? (MDS)
>
> (Typical??? values;??? main??? or
> sub??? RX,??? BW??? =??? 500??? Hz)
>
> 0.1-1.5??? MHz*:??? ??? ??? ??? Preamp??? OFF/1/2: -120/-130/-135??? ???
> dBm
> 1.5-23??? MHz:??? ??? ??? ??? ??? ??? ??? Preamp??? OFF/1/2: ???
> -120/-132/-137??? dBm
> 23-54??? MHz:??? ??? ??? ??? ??? ??? ??? ??? Preamp??? OFF/1/2: ??? ???
> -120/-132/-141??? dBm
> *0.1-1.5??? MHz??? MDS??? measured??? at??? RX??? antenna inputs.??? When
> using??? shared??? RX/TX??? antenna,??? sensitivity decreases???
> below??? 1.5
> MHz??? due??? to??? intentional??? high-pass??? response??? of T-R???
> switch.
>
>
> de Dave K5MWR
>
> On 1/19/2021 12:40, BRUCE WW8II wrote:
> > I work in the 2 to 3 db above the noise floor CW, and 6 to 10 db above
> the
> > noise floor on SSB now, (that is why I presently own a K3s and a P3VGA)
> so
> > I guess I will have to wait for the real answer. I really cannot
> > believe that Elecraft did not run their own test. If and when I spend my
> > cash I am not looking for the pretty blinkie colored lights and a fancy
> > screen, I want performance. My really big issue is: receiver noise
> floor,
> > sensitivity and DSP that does not distort or degrade the incoming signal.
> > But thank all of you for your input and I truly appreciate all the
> > comments.
> >
> > Bruce
> > WW8II
> >
> >
> >
> > On Tue, Jan 19, 2021 at 10:43 AM Louandzip via Elecraft <
> > elecraft at mailman.qth.net> wrote:
> >
> >> That's not a simple or easy question to answer, especially since
> there's
> >> been no independent test of a K4, and there are many different criteria
> >> that go into it. That said, I'll go out on a limb and say that in most
> >> all practical situations on the air, it won't be. I say that because
> I've
> >> listened to and half-assedly compared a number of very good radios and
> some
> >> less good radios on the air. They might sound different, and take some
> >> tweaking of the controls to make them sound a similar as possible, but
> in
> >> the end I couldn't copy sigs better on one than the other. The K3 is
> really
> >> good in the tests, and I'm confident the K4 will surpass it, but that's
> at
> >> level that will only matter in what I consider to be exceptional
> >> circumstances.
> >>
> >> I'll add that I'm not the radio connoisseur that some are, and what I
> feel
> >> is largely the same, others may find hugely different. That doesn't
> stop me
> >> from wanting the best, even if I believe it won't make a practical
> >> difference in my operating.
> >>
> >>
> >>
> >>
> >> On Tuesday, January 19, 2021, 12:47:17 AM MST, BRUCE WW8II <
> >> wa8hgx at gmail.com> wrote:
> >>
> >> I also would appreciate a real answer to the question. The question
> is
> >> will the K4 or K4D be as good or better on receive than my K3s with the
> >> 2.1kHz and the 200Hz filters.
> >>
> >> Bruce WW8II
> >>
> >> On Tue, Jan 19, 2021 at 12:56 AM RVZ via Elecraft <
> >> elecraft at mailman.qth.net>
> >> wrote:
> >>
> >>> I believe there are no crystal Roofing Filters in the standard K4
> model.
> >>> Yet the manual talks about "one set of receive filters". Please advise
> >> the
> >>> type and bandwidth of these filters? (DSP?)
> >>>
> >>> From the K4 Manual: There are three models: the basic K4, with one
> set
> >> of
> >>> receive filters and one analog-to-digital converter (ADC); the K4D,
> with
> >> a
> >>> second set of receive filters and a second ADC; and the K4HD, which
> adds
> >> a
> >>> superheterodyne front end that can be enabled as needed to provide even
> >>> greater dynamic range. The superhet module uses high-performance,
> >>> narrow-band crystal filters such as those used in the Elecraft K3S.
> >> Thanks
> >>> & 73, Dick- K9OM
> >>> ______________________________________________________________
> >>> Elecraft mailing list
> >>> Home: http://mailman.qth.net/mailman/listinfo/elecraft
> >>> Help: http://mailman.qth.net/mmfaq.htm
> >>> Post: mailto:Elecraft at mailman.qth.net
> >>>
> >>> This list hosted by: http://www.qsl.net
> >>> Please help support this email list: http://www.qsl.net/donate.html
> >>> Message delivered to wa8hgx at gmail.com
> >> ______________________________________________________________
> >> Elecraft mailing list
> >> Home: http://mailman.qth.net/mailman/listinfo/elecraft
> >> Help: http://mailman.qth.net/mmfaq.htm
> >> Post: mailto:Elecraft at mailman.qth.net
> >>
> >> This list hosted by: http://www.qsl.net
> >> Please help support this email list: http://www.qsl.net/donate.html
> >> Message delivered to louandzip at yahoo.com
> >>
> >> ______________________________________________________________
> >> Elecraft mailing list
> >> Home: http://mailman.qth.net/mailman/listinfo/elecraft
> >> Help: http://mailman.qth.net/mmfaq.htm
> >> Post: mailto:Elecraft at mailman.qth.net
> >>
> >> This list hosted by: http://www.qsl.net
> >> Please help support this email list: http://www.qsl.net/donate.html
> >> Message delivered to wa8hgx at gmail.com
> > ______________________________________________________________
> > Elecraft mailing list
> > Home: http://mailman.qth.net/mailman/listinfo/elecraft
> > Help: http://mailman.qth.net/mmfaq.htm
> > Post: mailto:Elecraft at mailman.qth.net
> >
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> > Please help support this email list: http://www.qsl.net/donate.html
> > Message delivered to dobox at suddenlink.net
> >
>
>
> ------------------------------
>
> Message: 2
> Date: Tue, 19 Jan 2021 19:13:18 +0000
> From: George Thornton <gthornton at thorntonmostullaw.com>
> To: BRUCE WW8II <wa8hgx at gmail.com>, Louandzip <louandzip at yahoo.com>
> Cc: elecraft <elecraft at mailman.qth.net>
> Subject: Re: [Elecraft] K4 Receive Filter question
> Message-ID:
> <
> MWHPR16MB1694594AF532CE3BA7A96CF0B4A30 at MWHPR16MB1694.namprd16.prod.outlook.com
> >
>
> Content-Type: text/plain; charset="us-ascii"
>
> I have followed the Sherwood Receiver test data over the years and I know
> Elecraft has always been in or near the top spot.
>
> I also would be reluctant to upgrade to a K4 if my K3 is the same or
> pretty close to the same in the key performance characteristics.
>
> I wonder whether we are nearing the theoretical limit of what can be
> gained in receiver performance.
>
> The difference among the top eight to ten on the Sherwood list is not
> likely to be practically significant.
>
> -----Original Message-----
> From: elecraft-bounces at mailman.qth.net <elecraft-bounces at mailman.qth.net>
> On Behalf Of BRUCE WW8II
> Sent: Tuesday, January 19, 2021 10:40 AM
> To: Louandzip <louandzip at yahoo.com>
> Cc: elecraft <elecraft at mailman.qth.net>
> Subject: Re: [Elecraft] K4 Receive Filter question
>
> I work in the 2 to 3 db above the noise floor CW, and 6 to 10 db above the
> noise floor on SSB now, (that is why I presently own a K3s and a P3VGA) so
> I guess I will have to wait for the real answer. I really cannot believe
> that Elecraft did not run their own test. If and when I spend my cash I am
> not looking for the pretty blinkie colored lights and a fancy screen, I
> want performance. My really big issue is: receiver noise floor,
> sensitivity and DSP that does not distort or degrade the incoming signal.
> But thank all of you for your input and I truly appreciate all the
> comments.
>
> Bruce
> WW8II
>
>
>
> On Tue, Jan 19, 2021 at 10:43 AM Louandzip via Elecraft <
> elecraft at mailman.qth.net> wrote:
>
> > That's not a simple or easy question to answer, especially since
> > there's been no independent test of a K4, and there are many different
> > criteria that go into it. That said, I'll go out on a limb and say
> > that in most all practical situations on the air, it won't be. I say
> > that because I've listened to and half-assedly compared a number of
> > very good radios and some less good radios on the air. They might
> > sound different, and take some tweaking of the controls to make them
> > sound a similar as possible, but in the end I couldn't copy sigs
> > better on one than the other. The K3 is really good in the tests, and
> > I'm confident the K4 will surpass it, but that's at level that will
> > only matter in what I consider to be exceptional circumstances.
> >
> > I'll add that I'm not the radio connoisseur that some are, and what I
> > feel is largely the same, others may find hugely different. That
> > doesn't stop me from wanting the best, even if I believe it won't make
> > a practical difference in my operating.
> >
> >
> >
> >
> > On Tuesday, January 19, 2021, 12:47:17 AM MST, BRUCE WW8II <
> > wa8hgx at gmail.com> wrote:
> >
> > I also would appreciate a real answer to the question. The question
> > is will the K4 or K4D be as good or better on receive than my K3s with
> > the 2.1kHz and the 200Hz filters.
> >
> > Bruce WW8II
> >
> > On Tue, Jan 19, 2021 at 12:56 AM RVZ via Elecraft <
> > elecraft at mailman.qth.net>
> > wrote:
> >
> > > I believe there are no crystal Roofing Filters in the standard K4
> model.
> > > Yet the manual talks about "one set of receive filters". Please
> > > advise
> > the
> > > type and bandwidth of these filters? (DSP?)
> > >
> > > From the K4 Manual: There are three models: the basic K4, with one
> > > set
> > of
> > > receive filters and one analog-to-digital converter (ADC); the K4D,
> > > with
> > a
> > > second set of receive filters and a second ADC; and the K4HD, which
> > > adds
> > a
> > > superheterodyne front end that can be enabled as needed to provide
> > > even greater dynamic range. The superhet module uses
> > > high-performance, narrow-band crystal filters such as those used in
> the Elecraft K3S.
> > Thanks
> > > & 73, Dick- K9OM
> > > ______________________________________________________________
> > > Elecraft mailing list
> > > Home: http://mailman.qth.net/mailman/listinfo/elecraft
> > > Help: http://mailman.qth.net/mmfaq.htm
> > > Post: mailto:Elecraft at mailman.qth.net
> > >
> > > This list hosted by: http://www.qsl.net Please help support this
> > > email list: http://www.qsl.net/donate.html Message delivered to
> > > wa8hgx at gmail.com
> > ______________________________________________________________
> > Elecraft mailing list
> > Home: http://mailman.qth.net/mailman/listinfo/elecraft
> > Help: http://mailman.qth.net/mmfaq.htm
> > Post: mailto:Elecraft at mailman.qth.net
> >
> > This list hosted by: http://www.qsl.net Please help support this email
> > list: http://www.qsl.net/donate.html Message delivered to
> > louandzip at yahoo.com
> >
> > ______________________________________________________________
> > Elecraft mailing list
> > Home: http://mailman.qth.net/mailman/listinfo/elecraft
> > Help: http://mailman.qth.net/mmfaq.htm
> > Post: mailto:Elecraft at mailman.qth.net
> >
> > This list hosted by: http://www.qsl.net Please help support this email
> > list: http://www.qsl.net/donate.html Message delivered to
> > wa8hgx at gmail.com
> ______________________________________________________________
> Elecraft mailing list
> Home: http://mailman.qth.net/mailman/listinfo/elecraft
> Help: http://mailman.qth.net/mmfaq.htm
> Post: mailto:Elecraft at mailman.qth.net
>
> This list hosted by: http://www.qsl.net
> Please help support this email list: http://www.qsl.net/donate.html
> Message delivered to gthornton at thorntonmostullaw.com
>
>
> ------------------------------
>
> Message: 3
> Date: Tue, 19 Jan 2021 19:38:58 +0000 (UTC)
> From: Louandzip <louandzip at yahoo.com>
> Cc: elecraft <elecraft at mailman.qth.net>
> Subject: Re: [Elecraft] K4 Receive Filter question
> Message-ID: <813993266.2163314.1611085138834 at mail.yahoo.com>
> Content-Type: text/plain; charset=UTF-8
>
> I own a radio that's currently #1 on Sherwood's list. My 20 year old K2
> is essentially equal at digging weak CW out of the noise (always dominated
> by band noise and not the noise floor of the rig) in virtually all
> situations I've run into. The K2 has no KSSB so I don't compare it on SSB.
> If I was up against a lot of really strong close-by sigs, presumably the
> new rig would win, but I haven't yet run into a situation with the two rigs
> side by side where big nearby sigs have actually caused a discernible
> difference.
> Comparing SSB with other rigs, the new rig can beat the others on
> readability of weak sigs in noise, but I don't think it's due to the
> fundamental performance numbers in these cases but rather the DSP algorithm
> which makes the difference, and I don't believe this is quantified in the
> testing done by Sherwood or ARRL, except perhaps in subjective comments in
> the text of a QST review. .
>
> On Tuesday, January 19, 2021, 12:13:20 PM MST, George Thornton <
> gthornton at thorntonmostullaw.com> wrote:
>
> I have followed the Sherwood Receiver test data over the years and I know
> Elecraft has always been in or near the top spot.
>
> I also would be reluctant to upgrade to a K4 if my K3 is the same or
> pretty close to the same in the key performance characteristics.
>
> I wonder whether we are nearing the theoretical limit of what can be
> gained in receiver performance.
>
> The difference among the top eight to ten on the Sherwood list is not
> likely to be practically significant.
>
> -----Original Message-----
> From: elecraft-bounces at mailman.qth.net <elecraft-bounces at mailman.qth.net>
> On Behalf Of BRUCE WW8II
> Sent: Tuesday, January 19, 2021 10:40 AM
> To: Louandzip <louandzip at yahoo.com>
> Cc: elecraft <elecraft at mailman.qth.net>
> Subject: Re: [Elecraft] K4 Receive Filter question
>
> I work in the 2 to 3 db above the noise floor CW, and 6 to 10 db above the
> noise floor on SSB now, (that is why I presently own a K3s and a P3VGA)? so
> I guess I will have to wait for the real answer. I really cannot believe
> that Elecraft did not run their own test. If and when I spend my cash I am
> not looking for the pretty blinkie colored lights and a fancy screen, I
> want performance.? My really big issue is: receiver noise floor,
> sensitivity and DSP that does not distort or degrade the incoming signal.
> But thank all of you for your input? and I truly appreciate all the
> comments.
>
> Bruce
> WW8II
>
>
>
> On Tue, Jan 19, 2021 at 10:43 AM Louandzip via Elecraft <
> elecraft at mailman.qth.net> wrote:
>
> >? That's not a simple or easy question to answer, especially since
> > there's been no independent test of a K4, and there are many different
> > criteria that go into it.? That said,? I'll go out on a limb and say
> > that in most all practical situations on the air, it won't be. I say
> > that because I've listened to and half-assedly compared a number of
> > very good radios and some less good radios on the air. They might
> > sound different, and take some tweaking of the controls to make them
> > sound a similar as possible, but in the end I couldn't copy sigs
> > better on one than the other. The K3 is really good in the tests, and
> > I'm confident the K4 will surpass it, but that's at level that will
> > only matter in what I consider to be exceptional circumstances.
> >
> > I'll add that I'm not the radio connoisseur that some are, and what I
> > feel is largely the same, others may find hugely different. That
> > doesn't stop me from wanting the best, even if I believe it won't make
> > a practical difference in my operating.
> >
> >
> >
> >
> >? ? On Tuesday, January 19, 2021, 12:47:17 AM MST, BRUCE WW8II <
> > wa8hgx at gmail.com> wrote:
> >
> >? I also would appreciate a real answer to the question.? The question
> > is will the K4 or K4D be as good or better on receive than my K3s with
> > the 2.1kHz and the 200Hz filters.
> >
> > Bruce WW8II
> >
> > On Tue, Jan 19, 2021 at 12:56 AM RVZ via Elecraft <
> > elecraft at mailman.qth.net>
> > wrote:
> >
> > > I believe there are no crystal Roofing Filters in the standard K4
> model.
> > > Yet the manual talks about "one set of receive filters".? Please
> > > advise
> > the
> > > type and bandwidth of these filters?? (DSP?)
> > >
> > > From the K4 Manual:? There are three models: the basic K4, with one
> > > set
> > of
> > > receive filters and one analog-to-digital converter (ADC); the K4D,
> > > with
> > a
> > > second set of receive filters and a second ADC; and the K4HD, which
> > > adds
> > a
> > > superheterodyne front end that can be enabled as needed to provide
> > > even greater dynamic range. The superhet module uses
> > > high-performance, narrow-band crystal filters such as those used in
> the Elecraft K3S.
> > Thanks
> > > & 73, Dick- K9OM
> > > ______________________________________________________________
> > > Elecraft mailing list
> > > Home: http://mailman.qth.net/mailman/listinfo/elecraft
> > > Help: http://mailman.qth.net/mmfaq.htm
> > > Post: mailto:Elecraft at mailman.qth.net
> > >
> > > This list hosted by: http://www.qsl.net Please help support this
> > > email list: http://www.qsl.net/donate.html Message delivered to
> > > wa8hgx at gmail.com
> > ______________________________________________________________
> > Elecraft mailing list
> > Home: http://mailman.qth.net/mailman/listinfo/elecraft
> > Help: http://mailman.qth.net/mmfaq.htm
> > Post: mailto:Elecraft at mailman.qth.net
> >
> > This list hosted by: http://www.qsl.net Please help support this email
> > list: http://www.qsl.net/donate.html Message delivered to
> > louandzip at yahoo.com
> >
> > ______________________________________________________________
> > Elecraft mailing list
> > Home: http://mailman.qth.net/mailman/listinfo/elecraft
> > Help: http://mailman.qth.net/mmfaq.htm
> > Post: mailto:Elecraft at mailman.qth.net
> >
> > This list hosted by: http://www.qsl.net Please help support this email
> > list: http://www.qsl.net/donate.html Message delivered to
> > wa8hgx at gmail.com
> ______________________________________________________________
> Elecraft mailing list
> Home: http://mailman.qth.net/mailman/listinfo/elecraft
> Help: http://mailman.qth.net/mmfaq.htm
> Post: mailto:Elecraft at mailman.qth.net
>
> This list hosted by: http://www.qsl.net
> Please help support this email list: http://www.qsl.net/donate.html
> Message delivered to gthornton at thorntonmostullaw.com
>
>
> ------------------------------
>
> Message: 4
> Date: Tue, 19 Jan 2021 14:07:42 -0700
> From: Wes <wes_n7ws at triconet.org>
> To: elecraft at mailman.qth.net
> Subject: Re: [Elecraft] K4 Receive Filter question
> Message-ID: <4981567a-24b1-c38d-a7bd-b63b50677d41 at triconet.org>
> Content-Type: text/plain; charset=utf-8; format=flowed
>
> I happen to own the K3S that is #5 or Rob's list.? I also got tired of
> waiting
> on the K4 and having a burning desire for a new radio I have a month-old
> TS-890,
> which is now my primary radio.? The K3S is set up in a receive-only state,
> sharing the RX antenna out of the '890.
>
> A few mornings ago I was tuning 160 near sunrise and copied a fishing buoy
> 60 Hz
> above one of the commonly used frequencies (forget which one).? My friend,
> and
> local ham, N7DD began calling CQ 60 Hz below the buoy.? Larry runs an Icom
> 7851,
> which is very clean and a BIG amplifier.? He is at least S9+40 db.? On the
> TS-890, cranked down to 80 Hz BW,? I could still copy the buoy which was
> S6 or
> so.? On the K3S I heard N7DD calling CQ.
>
> Without QRM the rigs are comparable at hearing signals in the noise but the
> Kenwood sounds better.
>
> Wes? N7WS
>
> On 1/19/2021 12:38 PM, Louandzip via Elecraft wrote:
> > I own a radio that's currently #1 on Sherwood's list. My 20 year old
> K2 is essentially equal at digging weak CW out of the noise (always
> dominated by band noise and not the noise floor of the rig) in virtually
> all situations I've run into. The K2 has no KSSB so I don't compare it on
> SSB. If I was up against a lot of really strong close-by sigs, presumably
> the new rig would win, but I haven't yet run into a situation with the two
> rigs side by side where big nearby sigs have actually caused a discernible
> difference.
> > Comparing SSB with other rigs, the new rig can beat the others on
> readability of weak sigs in noise, but I don't think it's due to the
> fundamental performance numbers in these cases but rather the DSP algorithm
> which makes the difference, and I don't believe this is quantified in the
> testing done by Sherwood or ARRL, except perhaps in subjective comments in
> the text of a QST review. .
> >
> > On Tuesday, January 19, 2021, 12:13:20 PM MST, George Thornton <
> gthornton at thorntonmostullaw.com> wrote:
> >
> > I have followed the Sherwood Receiver test data over the years and I
> know Elecraft has always been in or near the top spot.
> >
> > I also would be reluctant to upgrade to a K4 if my K3 is the same or
> pretty close to the same in the key performance characteristics.
> >
> > I wonder whether we are nearing the theoretical limit of what can be
> gained in receiver performance.
> >
> > The difference among the top eight to ten on the Sherwood list is not
> likely to be practically significant.
>
>
>
> ------------------------------
>
> Message: 5
> Date: Tue, 19 Jan 2021 13:35:17 -0800
> From: Fred Jensen <k6dgw at foothill.net>
> To: elecraft at mailman.qth.net
> Subject: Re: [Elecraft] Efficiency of MFJ remotely-tuned loop antennas
> Message-ID: <0b8a4a5b-c6f0-9d70-3a21-f056295feaeb at foothill.net>
> Content-Type: text/plain; charset=utf-8; format=flowed
>
> The plates in the two air variables in the [now ancient] ARC-5 command
> TX from WW2 were very securely welded in place to the rotor axle.? We'd
> remove many of the rotor plates and re-pad it with a fixed capacitor to
> spread out the ham band on the dial.? It took a lot of bending back and
> forth to break the welds.? Lower power loops often use butterfly caps
> since there is no resistive loss through the rotor connection.? Higher
> powered loops often use vacuum variables because of the high voltages,
> although I saw a design not long ago that used two coaxial copper pipes
> with a PVC pipe as the insulator.? The inside conductor was mounted to a
> long threaded rod moving it in and out of the outer conductor.
>
> In your list of pros, you might note that while the bi-directional
> primary lobes of the loop when mounted vertically are very broad, the
> null perpendicular to the plane of the loop is extremely narrow and
> deep.? You can use it to null out noise or even another signal without
> sacrificing much of anything in the forward direction.
>
> My Alexloop works ok on 30, poorly on 40, and really seems to come into
> its own on 20 and up.
>
> 73,
>
> Fred ["Skip"] K6DGW
> Sparks NV DM09dn
> Washoe County
>
> On 1/18/2021 8:54 PM, Alan Bloom wrote:
> > > There is a reason why top quality variable capacitors often use
> > welded plates.
> >
> > I believe they do weld the capacitor plates and also weld the loop to
> > the capacitor.? (I don't have one, but that's what I've read.)
> >
> > > Yours is a limited theoretical analysis ... not a practical one.
> >
> > A number of reviews I have read (including the QST review of August
> > 1994) have reported comparable performance to full-sized wire antennas
> > located on the same site.? If the loop is down by, say, 3 dB, that's
> > only half an S unit, which would hardly? be noticeable in the QSB of a
> > typical amateur band.
> >
> >
> > As I see it, the advantages of the MFJ-1786 10-30 MHz loop are:
> >
> > - Continuous coverage on 6 amateur bands.? A convenient way to cover
> > all the WARC bands.
> > - Small and light.
> > - Omni-directional (when mounted horizontally)? so does not need a rotor.
> > - No control cable required - control voltage is fed through the coax.
> > - Narrow bandwidth provides excellent RF selectivity.? Might be good
> > on Field Day to reduce inter-station QRM.
> > - Users have reported lower receiver noise compared to wire antennas.?
> > No doubt that is because the isolated pickup loop prevents feedline
> > radiation/pickup.
> >
> > And the disadvantages:
> >
> > - Expensive ($500 list price)
> > - Less gain than a simple dipole (although you would theoretically
> > need 6 of them).
> > - Fiddly to tune.? If you QSY too far you have to re-tune.
> > - MFJ quality control leaves something to be desired.? (You may have
> > to open it up when you get it and? make minor repairs.)
> > - You have to pay attention to the problem of entry of water and/or
> > bugs into the housing.
> > - The controller can be damaged by a DC short in the coax e.g. from an
> > shorting-type antenna switch.? (I don't understand why MFJ didn't
> > include a fuse or some other way to protect the controller.)
> >
> > I probably wouldn't buy the 7-21 MHz MFJ-1788 because of the poor
> > efficiency at 7 MHz.? I think you'd have a better signal just using
> > the coax as a random end-fed wire (with a tuner).
> >
> > Alan N1AL
> >
> >
> > On 1/18/2021 8:17 PM, David Gilbert wrote:
> >>
> >> You are neglecting the losses in various connections in the system
> >> ... including possibly the construction of the capacitor itself. I
> >> don't believe that they are insignificant.? There is a reason why top
> >> quality variable capacitors often use welded plates.
> >>
> >> I would also guess that contact resistance is worse for dissimilar
> >> materials, such as a copper wire to an aluminum tube.
> >>
> >> Yours is a limited theoretical analysis ... not a practical one.
> >>
> >> Dave?? AB7E
> >>
> >>
> >>
> >> On 1/18/2021 5:38 PM, Alan Bloom wrote:
> >>> Well let's see...
> >>>
> >>> Radiation resistance of a small loop is 31,171 * (Area /
> >>> wavelength^2)^2
> >>>
> >>> For a loop with a 91cm diameter at 14 MHz, I believe that comes out
> >>> to 0.064 ohms.
> >>>
> >>> Assuming the loss is due to the RF resistance of the loop:
> >>>
> >>> From the internet I get the volume resistivity and skin depth for
> >>> 6063 aluminum is 0.03 microohms-meter and 23.3 micrometers
> >>> respectively, so the surface resistivity is 0.03/23.3 = 0.0013 ohms
> >>> per square.? The outside circumference of the tubing is PI * 1.05" =
> >>> 3.3" and the loop length is PI * 36" = 113" so the loss resistance
> >>> is .0013 * 113/3.3 = 0.045 ohms.
> >>>
> >>> So I calculate an efficiency of 0.064 / (0.064 + 0.045) = 59%
> >>>
> >>> So worse than AEA claimed, but in the ballpark.
> >>>
> >>> Alan N1AL
> >>>
> >>>
> >>>
> >>>
> >>> On 1/18/2021 3:39 PM, Wayne Burdick wrote:
> >>>> Hi Alan,
> >>>>
> >>>> 72% sounds a bit high. Is this number based on loop size alone ("in
> >>>> theory")? Or are they taking conductor geometry and other losses
> >>>> into account?
> >>>>
> >>>> Wayne
> >>>> N6KR
> >>>>
> >>>>
> >>>>> On Jan 18, 2021, at 2:05 PM, Alan Bloom <n1al at sonic.net> wrote:
> >>>>>
> >>>>> MFJ makes a pair of small, remotely-tuned loop antennas, the
> >>>>> MFJ-1786 that covers 10-30 MHz and the MFJ-1788 that covers 7 to
> >>>>> 21+ MHz.? As far as I can tell, the two antennas are identical
> >>>>> except for the size of the tuning capacitor.? Each consists of a 3
> >>>>> foot (91 cm) diameter loop made of aluminum tubing and a plastic
> >>>>> housing that contains the tuning capacitor, motor, and coupling
> >>>>> loop. No control cable is required since the control voltage is
> >>>>> sent from the control box in the shack to the motor in the antenna
> >>>>> via the coaxial cable.
> >>>>>
> >>>>> Before I purchase one of these I wanted to get an idea of the
> >>>>> efficiency of such a small loop.? MFJ is silent on the subject so
> >>>>> I did my own calculations.? The calculations and results are on a
> >>>>> 1-page document that I uploaded to Dropbox and can be downloaded
> >>>>> here:
> >>>>>
> >>>>> https://www.dropbox.com/s/l8mv67cjrck2ssn/MFJ-1786-1788.pdf?dl=0
> >>>>>
> >>>>> My calculations are based on the assumption that the efficiency of
> >>>>> the MFJ antennas is similar to the (no longer manufactured) AEA
> >>>>> Isoloop (my reasoning for that is in the document) and that AEA's
> >>>>> specification of 72% efficiency at 14 MHz is correct.? From that
> >>>>> number I can calculate the efficiency and gain on all the other
> >>>>> bands.
> >>>>>
> >>>>> If you don't want to download the document, here is a summary of
> >>>>> the results:
> >>>>>
> >>>>> Freq??? Eff??? Gain with respect to a half-wave dipole
> >>>>> MHz??? dB??? dBd
> >>>>> 7.0??? -7.3??? -7.7
> >>>>> 10.1??? -3.5??? -3.9
> >>>>> 14.0??? -1.4??? -1.8
> >>>>> 18.068??? -0.6??? -1.0
> >>>>> 21.0??? -0.4??? -0.8
> >>>>> 24.89??? -0.2??? -0.6
> >>>>> 28.0??? -0.15??? -0.5
> >>>>>
> >>>>> I'd be interested in any comments people may have on the accuracy of
> >>>>> my assumptions and calculations in the document.
> >>>>>
> >>>>> Alan N1AL
> >>>>> ______________________________________________________________
> >>>>> Elecraft mailing list
> >>>>> Home: http://mailman.qth.net/mailman/listinfo/elecraft
> >>>>> Help: http://mailman.qth.net/mmfaq.htm
> >>>>> Post: mailto:Elecraft at mailman.qth.net
> >>>>>
> >>>>> This list hosted by: http://www.qsl.net
> >>>>> Please help support this email list: http://www.qsl.net/donate.html
> >>>>> Message delivered to n6kr at elecraft.com
> >>>>
> >>>
> >>> ______________________________________________________________
> >>> Elecraft mailing list
> >>> Home: http://mailman.qth.net/mailman/listinfo/elecraft
> >>> Help: http://mailman.qth.net/mmfaq.htm
> >>> Post: mailto:Elecraft at mailman.qth.net
> >>>
> >>> This list hosted by: http://www.qsl.net
> >>> Please help support this email list: http://www.qsl.net/donate.html
> >>> Message delivered to ab7echo at gmail.com
> >>
> >> ______________________________________________________________
> >> Elecraft mailing list
> >> Home: http://mailman.qth.net/mailman/listinfo/elecraft
> >> Help: http://mailman.qth.net/mmfaq.htm
> >> Post: mailto:Elecraft at mailman.qth.net
> >>
> >> This list hosted by: http://www.qsl.net
> >> Please help support this email list: http://www.qsl.net/donate.html
> >> Message delivered to alan at elecraft.com
> >
> > ______________________________________________________________
> > Elecraft mailing list
> > Home: http://mailman.qth.net/mailman/listinfo/elecraft
> > Help: http://mailman.qth.net/mmfaq.htm
> > Post: mailto:Elecraft at mailman.qth.net
> >
> > This list hosted by: http://www.qsl.net
> > Please help support this email list: http://www.qsl.net/donate.html
> > Message delivered to k6dgw at foothill.net
>
>
>
> ------------------------------
>
> Message: 6
> Date: Tue, 19 Jan 2021 16:35:55 -0500
> From: Joseph Shuman <oldmanshu at icloud.com>
> To: Elecraft Mail Server <elecraft at mailman.qth.net>
> Subject: [Elecraft] Absurd remarks about FCC and ARRL notices.
> Message-ID: <F7546386-7DA0-4E3A-B270-4BE2F8167C93 at icloud.com>
> Content-Type: text/plain; charset=utf-8
>
> This new OT topic and the preceding old OT topic combined has been one of
> the greatest examples of free speech I have ever seen on-line. Kudos to
> this forum for open and honest participation, it fills me with hope to see
> such a wonderful exchange of contrasting viewpoints without digital
> censorship. It may be ?OT? but the unprecedented notice by the FCC and the
> ARRL should be openly discussed by all licensees. After all, our hobby is
> an advancement of free speech that pre-dates the digital age, and in my
> view free speech is NEVER ?absurd.?
>
> Keeping Watch -
> shu
>
> Joe Shuman, NZ8P
>
> ------------------------------
>
> Message: 7
> Date: Tue, 19 Jan 2021 14:37:15 -0700
> From: kennedyjp <kennedyjp at cableone.net>
> To: Geoffrey Feldman <geoffreyf at comcast.net>,
> elecraft at mailman.qth.net, elecraft-owner at mailman.qth.net
> Subject: Re: [Elecraft] Absurd remarks about FCC and ARRL notices.
> Message-ID: <00.05.30565.C0157006 at smtp03.lapis.bos.sync.lan>
> Content-Type: text/plain; charset=utf-8
>
> Enough already. Keep your political views and beliefs off this forum.? Not
> needed, not wanted.?JimW7OUU?Sent via the Samsung Galaxy S9+, an AT&T 5G
> Evolution capable smartphone
> -------- Original message --------From: Geoffrey Feldman <
> geoffreyf at comcast.net> Date: 1/18/21 19:06 (GMT-07:00) To:
> elecraft at mailman.qth.net, elecraft-owner at mailman.qth.net Subject:
> [Elecraft] Absurd remarks about FCC and ARRL notices. The letters to this
> list regarding FCC and ARRL notices? were factuallyfalse and have
> absolutely nothing to do with Elecraft products exceptperhaps as some might
> choose to use such radio transmitting products tocommit unjustified
> criminal acts.? Those who have false pride in theircomments can read what I
> write here and readily determine their factualmistakes for themselves.?
> The reason for the FCC and ARRL Notices is factually not because of the
> nextadministration but the present one which incited a riot. IN THAT?
> CRIMINALOFFENSE, Radios were used unlawfully to commit Federal offenses
> againstdemocracy and the Constitution.?? I also see the FCC notice as one
> askingcivilians to report criminal use of Amateur and other
> civiliancommunications g
> ear - This I will do as well as working with other lawabiding hams to
> find, locate and document criminal use, especially againstthe Constitution
> and US Government.?? The reason why Washington D.C. is anarmed camp is that
> on 1/6 We had a president incite insurrection. ThatPresident is the only
> one with two impeachments, both of which are morelegally substantive than
> the two which preceded them.? Those personscriminally acted to disrupt
> lawful congressional preceding.? Many claim tohave done this on behalf of
> the current President, failing to understandnobody is above the law and any
> apparent direction to violate theconstitution is illegal no matter the
> source. That entire event wasunprecedented in the USA and the responses are
> and will be as well.? Theelection was not fraudulent.? It was certified in
> each of the states, inmost cases by Republican elected authorities.? Over
> 60 cases whose lawyersclaimed fraud, were thrown out by Federal judges,
> many of whom appointed bythe cur
> rent President.? In several cases these judges noted there was noevidence
> at all and in the rest, no evidence that would show a change in theend
> result for that state.? The Supreme Court also spoke on this matter
> -against the Presidents false claims.? There are over 60 case
> transcripts,public oral opinions by the judges and supreme court, as well
> as the remarksof AG Barr who quit in disgust with his own
> administration.Frankly to blame the next administration for the FCC and
> ARRL notice isidiotic - they are not in power yet.? That assault on the
> Capitol wasunprecedented and THAT is what has led to the other
> unprecedented things.The reason is that under our constitution, nobody is
> above the law,including the President and those who stormed the capitol.?
> Acting toenforce the law should not be offensive to anyone who claims to be
> a patriotor writing in the traditions of Amateur Radio or the ARRL.??
> Interesting? toknow the false sympathies of some of you though. I encourage
> you t
> o spendthe reasonable efforts of citizens to go and learn what you
> didn't. Geoffrey
> FeldmanW1GCF______________________________________________________________Elecraft
> mailing listHome: http://mailman.qth.net/mailman/listinfo/elecraftHelp:
> http://mailman.qth.net/mmfaq.htmPost: mailto:Elecraft at mailman.qth.netThis
> list hosted by: http://www.qsl.netPlease help support this email list:
> http://www.qsl.net/donate.htmlMessage delivered to kennedyjp at cableone.net
>
> ------------------------------
>
> Message: 8
> Date: Tue, 19 Jan 2021 21:47:59 +0000
> From: Al London <londonasl at gmail.com>
> To: Geoffrey Feldman <geoffreyf at comcast.net>,
> "elecraft at mailman.qth.net" <elecraft at mailman.qth.net>,
> "elecraft-owner at mailman.qth.net" <
> elecraft-owner at mailman.qth.net>,
> kennedyjp <kennedyjp at cableone.net>
> Subject: Re: [Elecraft] Absurd remarks about FCC and ARRL notices.
> Message-ID:
> <
> BN7PR05MB4257DB73EBDFDF3CCE4277F0A5A30 at BN7PR05MB4257.namprd05.prod.outlook.com
> >
>
> Content-Type: text/plain; charset="us-ascii"
>
> Jim
>
> Thank you for your concise comments. Greatly appreciated. The last thing
> we need is more politics.
>
> Al
> N4DIY
>
> Sent from my Verizon, Samsung Note20 smartphone
>
> ________________________________
> From: elecraft-bounces at mailman.qth.net <elecraft-bounces at mailman.qth.net>
> on behalf of kennedyjp <kennedyjp at cableone.net>
> Sent: Tuesday, January 19, 2021 4:37:15 PM
> To: Geoffrey Feldman <geoffreyf at comcast.net>; elecraft at mailman.qth.net <
> elecraft at mailman.qth.net>; elecraft-owner at mailman.qth.net <
> elecraft-owner at mailman.qth.net>
> Subject: Re: [Elecraft] Absurd remarks about FCC and ARRL notices.
>
> Enough already. Keep your political views and beliefs off this forum. Not
> needed, not wanted. JimW7OUU Sent via the Samsung Galaxy S9+, an AT&T 5G
> Evolution capable smartphone
> -------- Original message --------From: Geoffrey Feldman <
> geoffreyf at comcast.net> Date: 1/18/21 19:06 (GMT-07:00) To:
> elecraft at mailman.qth.net, elecraft-owner at mailman.qth.net Subject:
> [Elecraft] Absurd remarks about FCC and ARRL notices. The letters to this
> list regarding FCC and ARRL notices were factuallyfalse and have
> absolutely nothing to do with Elecraft products exceptperhaps as some might
> choose to use such radio transmitting products tocommit unjustified
> criminal acts. Those who have false pride in theircomments can read what I
> write here and readily determine their factualmistakes for themselves.
> The reason for the FCC and ARRL Notices is factually not because of the
> nextadministration but the present one which incited a riot. IN THAT
> CRIMINALOFFENSE, Radios were used unlawfully to commit Federal offenses
> againstdemocracy and the Constitution. I also see the FCC notice as one
> askingcivilians to report criminal use of Amateur and other
> civiliancommunications g
> ear - This I will do as well as working with other lawabiding hams to
> find, locate and document criminal use, especially againstthe Constitution
> and US Government. The reason why Washington D.C. is anarmed camp is that
> on 1/6 We had a president incite insurrection. ThatPresident is the only
> one with two impeachments, both of which are morelegally substantive than
> the two which preceded them. Those personscriminally acted to disrupt
> lawful congressional preceding. Many claim tohave done this on behalf of
> the current President, failing to understandnobody is above the law and any
> apparent direction to violate theconstitution is illegal no matter the
> source. That entire event wasunprecedented in the USA and the responses are
> and will be as well. Theelection was not fraudulent. It was certified in
> each of the states, inmost cases by Republican elected authorities. Over
> 60 cases whose lawyersclaimed fraud, were thrown out by Federal judges,
> many of whom appointed bythe cur
> rent President. In several cases these judges noted there was noevidence
> at all and in the rest, no evidence that would show a change in theend
> result for that state. The Supreme Court also spoke on this matter
> -against the Presidents false claims. There are over 60 case
> transcripts,public oral opinions by the judges and supreme court, as well
> as the remarksof AG Barr who quit in disgust with his own
> administration.Frankly to blame the next administration for the FCC and
> ARRL notice isidiotic - they are not in power yet. That assault on the
> Capitol wasunprecedented and THAT is what has led to the other
> unprecedented things.The reason is that under our constitution, nobody is
> above the law,including the President and those who stormed the capitol.
> Acting toenforce the law should not be offensive to anyone who claims to be
> a patriotor writing in the traditions of Amateur Radio or the ARRL.
> Interesting toknow the false sympathies of some of you though. I
> encourage you t
> o spendthe reasonable efforts of citizens to go and learn what you
> didn't. Geoffrey
> FeldmanW1GCF______________________________________________________________Elecraft
> mailing listHome: http://mailman.qth.net/mailman/listinfo/elecraftHelp:
> http://mailman.qth.net/mmfaq.htmPost: mailto:Elecraft at mailman.qth.netThis
> list hosted by: http://www.qsl.netPlease help support this email list:
> http://www.qsl.net/donate.htmlMessage delivered to kennedyjp at cableone.net
> ______________________________________________________________
> Elecraft mailing list
> Home: http://mailman.qth.net/mailman/listinfo/elecraft
> Help: http://mailman.qth.net/mmfaq.htm
> Post: mailto:Elecraft at mailman.qth.net
>
> This list hosted by: http://www.qsl.net
> Please help support this email list: http://www.qsl.net/donate.html
> Message delivered to londonasl at gmail.com
>
>
> ------------------------------
>
> Message: 9
> Date: Tue, 19 Jan 2021 14:00:23 -0800
> From: Wayne Burdick <n6kr at elecraft.com>
> To: Elecraft Reflector <elecraft at mailman.qth.net>
> Subject: Re: [Elecraft] Absurd remarks about FCC and ARRL notices.
> Message-ID: <21A150C9-A28F-4833-9EF3-BD2B8B6B4B01 at elecraft.com>
> Content-Type: text/plain; charset=us-ascii
>
> My overworked business partner (WA6HHQ) is rightly trying to shut down
> this thread. We certainly don't want red and blue Elecraft forums.
>
> Before he does, I'd like to slip in a final comment.
>
> The intent of my posting (yes, I started this) was to call attention to a
> highly unusual FCC announcement that was assumed to be of general interest.
> Similar postings were made to many other ham forums in the same time frame.
>
> It's clear that the message has been received loud and clear.
> Interpretations are hereby officially left to the reader as a [private]
> exercise.
>
> Thanks,
>
> Wayne
> N6KR
>
>
>
> ------------------------------
>
> Message: 10
> Date: Tue, 19 Jan 2021 14:06:19 -0800
> From: Paul GACEK <paul.gacek at me.com>
> To: Elecraft Reflector <elecraft at mailman.qth.net>
> Subject: [Elecraft] Something different, old memories and using the
> KX3
> Message-ID: <686AC717-5583-4B7C-A118-79F9AA256230 at me.com>
> Content-Type: text/plain; charset=utf-8
>
> I?ve been sorting out some of my LoTW records which inevitably covered the
> 2016 NPOTA event.
>
> I did a lot of low power phone activations in the Western USA using my KX3
> for NPOTA many in the San Francisco Bay Area when I was living in that fine
> city.
>
> Loved the event, love my KX3 and just wanted to jot down a few memories
> for me to re-read over a glass of whisky sometime in the future and not
> surprisingly thinking about the past is almost as good as going out now
> which clearly isn?t so easy.
>
> No technical insights nor stellar Q counts here?..just old fashioned
> memories of a more human kind.
>
> Delete if not interested or peruse at
> https://nomadic.blog/2021/01/19/camaraderie-in-the-age-of-national-parks-on-the-air/
> <
> https://nomadic.blog/2021/01/19/camaraderie-in-the-age-of-national-parks-on-the-air/
> >
>
> Paul
> W6PNG/M0SNA
> www.nomadic.blog<http://www.nomadic.blog> <http://www.nomadic.blog/>
>
>
>
> ------------------------------
>
> Message: 11
> Date: Tue, 19 Jan 2021 17:14:47 -0500
> From: Dave Sublette <k4to.dave at gmail.com>
> To: Paul GACEK <paul.gacek at me.com>
> Cc: Elecraft Reflector <elecraft at mailman.qth.net>
> Subject: Re: [Elecraft] Something different, old memories and using
> the KX3
> Message-ID:
> <
> CAKynJKnRZK352b_++HYCx6xS3EH_31Z60Lp0Uzi8LxFL+-0E9Q at mail.gmail.com>
> Content-Type: text/plain; charset="UTF-8"
>
> Well done, Paul. It is a joy to read your account and I know you have had
> some great adventures. You are right about we older folks who cherish the
> memories of our adventures through the years.
>
> 73,
>
> Dave, K4TO
>
> On Tue, Jan 19, 2021 at 5:06 PM Paul GACEK via Elecraft <
> elecraft at mailman.qth.net> wrote:
>
> > I?ve been sorting out some of my LoTW records which inevitably covered
> the
> > 2016 NPOTA event.
> >
> > I did a lot of low power phone activations in the Western USA using my
> KX3
> > for NPOTA many in the San Francisco Bay Area when I was living in that
> fine
> > city.
> >
> > Loved the event, love my KX3 and just wanted to jot down a few memories
> > for me to re-read over a glass of whisky sometime in the future and not
> > surprisingly thinking about the past is almost as good as going out now
> > which clearly isn?t so easy.
> >
> > No technical insights nor stellar Q counts here?..just old fashioned
> > memories of a more human kind.
> >
> > Delete if not interested or peruse at
> >
> https://nomadic.blog/2021/01/19/camaraderie-in-the-age-of-national-parks-on-the-air/
> > <
> >
> https://nomadic.blog/2021/01/19/camaraderie-in-the-age-of-national-parks-on-the-air/
> > >
> >
> > Paul
> > W6PNG/M0SNA
> > www.nomadic.blog<http://www.nomadic.blog> <http://www.nomadic.blog/>
> >
> > ______________________________________________________________
> > Elecraft mailing list
> > Home: http://mailman.qth.net/mailman/listinfo/elecraft
> > Help: http://mailman.qth.net/mmfaq.htm
> > Post: mailto:Elecraft at mailman.qth.net
> >
> > This list hosted by: http://www.qsl.net
> > Please help support this email list: http://www.qsl.net/donate.html
> > Message delivered to k4to at arrl.net
>
>
> ------------------------------
>
> Message: 12
> Date: Tue, 19 Jan 2021 17:54:58 -0500
> From: <hbjr at optilink.us>
> To: "'Wayne Burdick'" <n6kr at elecraft.com>, "'Elecraft Reflector'"
> <elecraft at mailman.qth.net>
> Subject: Re: [Elecraft] Absurd remarks about FCC and ARRL notices.
> Message-ID: <[email protected]>
> Content-Type: text/plain; charset="us-ascii"
>
> Thanks for posting this originally - I wouldn't have seen it otherwise.
>
> The problem with political discussions - especially in the world of 24/7
> news coverage and op eds - we all show how uneducated we are on the topics
> and are willing to believe what we are told without doing the research.
>
> The rhetoric is all too often divisive. We can all agree on how fun and
> fulfilling ham radio is to each of us in its own special way - let's stick
> to that.
>
> Hank
> K4HYJ
>
> -----Original Message-----
> From: elecraft-bounces at mailman.qth.net <elecraft-bounces at mailman.qth.net>
> On
> Behalf Of Wayne Burdick
> Sent: Tuesday, January 19, 2021 5:00 PM
> To: Elecraft Reflector <elecraft at mailman.qth.net>
> Subject: Re: [Elecraft] Absurd remarks about FCC and ARRL notices.
>
> My overworked business partner (WA6HHQ) is rightly trying to shut down this
> thread. We certainly don't want red and blue Elecraft forums.
>
> Before he does, I'd like to slip in a final comment.
>
> The intent of my posting (yes, I started this) was to call attention to a
> highly unusual FCC announcement that was assumed to be of general interest.
> Similar postings were made to many other ham forums in the same time frame.
>
> It's clear that the message has been received loud and clear.
> Interpretations are hereby officially left to the reader as a [private]
> exercise.
>
> Thanks,
>
> Wayne
> N6KR
>
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>
> ------------------------------
>
> Message: 13
> Date: Tue, 19 Jan 2021 15:56:16 -0700
> From: Alan Bloom <n1al at sonic.net>
> To: Wayne Burdick <n6kr at elecraft.com>
> Cc: Elecraft Reflector <elecraft at mailman.qth.net>
> Subject: Re: [Elecraft] Efficiency of MFJ remotely-tuned loop antennas
> Message-ID: <00ce6b0e-ceed-f42e-f108-2063928f7184 at sonic.net>
> Content-Type: text/plain; charset=utf-8; format=flowed
>
> I've been convinced that AEA's specification of 72% efficiency for the
> Isoloop at 14 MHz is too high, certainly too high for the MFJ antennas.?
> So I re-did the calculations using the 59% efficiency figure calculated
> below.? The new results can be downloaded here:
>
> https://www.dropbox.com/s/ve1v49b3gjvmt64/MFJ-1786-1788_2.pdf?dl=0
>
> If you don't want to download the (1-page) document with the pretty
> graph, here's a synopsis of the results:
>
> Freq? ? ? Eff.???? Gain with respect to a 1/2-wavelength dipole
> MHz?? ?? dB????? dBd
> 7.0??? ? ?? -9.5??? -9.9
> 10.1?? ? ? -5.1??? -5.5
> 14.0?? ? ? -2.3??? -2.7
> 18.068 ? -1.1??? -1.5
> 21.0?????? -0.7??? -1.1
> 24.89???? -0.4??? -.8
> 28.0?????? -0.26? -0.65
>
> My basic conclusions still stand.? With almost minus 10 dBd of gain on 7
> MHz, the 40 meter coverage of the MFJ-1788 doesn't seem very useful.?
> That is confirmed by some of the reviews I have seen.? I think you'd get
> better results by just loading up the coax feedline as a random-wire
> antenna with a tuner.
>
> The 10 MHz performance is a little better.? Good enough to at least
> allow you to get on the 30 meter band.
>
> On the higher bands, the gain is within less than 3 dB of a full-sized
> dipole, which seems a useful trade-off for its small size and wide-band
> continuous coverage.
>
> Disclaimer:? Again, I have never seen one of these things so this is all
> based on theory and on the many reviews I have read.? Even if my figures
> are off a bit, at least this gives an idea of the relative performance
> on the various bands.
>
> Alan N1AL
>
>
>
> On 1/18/2021 5:38 PM, Alan Bloom wrote:
> > Well let's see...
> >
> > Radiation resistance of a small loop is 31,171 * (Area / wavelength^2)^2
> >
> > For a loop with a 91cm diameter at 14 MHz, I believe that comes out to
> > 0.064 ohms.
> >
> > Assuming the loss is due to the RF resistance of the loop:
> >
> > From the internet I get the volume resistivity and skin depth for 6063
> > aluminum is 0.03 microohms-meter and 23.3 micrometers respectively, so
> > the surface resistivity is 0.03/23.3 = 0.0013 ohms per square.? The
> > outside circumference of the tubing is PI * 1.05" = 3.3" and the loop
> > length is PI * 36" = 113" so the loss resistance is .0013 * 113/3.3 =
> > 0.045 ohms.
> >
> > So I calculate an efficiency of 0.064 / (0.064 + 0.045) = 59%
> >
> > So worse than AEA claimed, but in the ballpark.
> >
> > Alan N1AL
> >
> >
> >
> >
> > On 1/18/2021 3:39 PM, Wayne Burdick wrote:
> >> Hi Alan,
> >>
> >> 72% sounds a bit high. Is this number based on loop size alone ("in
> >> theory")? Or are they taking conductor geometry and other losses into
> >> account?
> >>
> >> Wayne
> >> N6KR
> >>
> >>
> >>> On Jan 18, 2021, at 2:05 PM, Alan Bloom <n1al at sonic.net> wrote:
> >>>
> >>> MFJ makes a pair of small, remotely-tuned loop antennas, the
> >>> MFJ-1786 that covers 10-30 MHz and the MFJ-1788 that covers 7 to 21+
> >>> MHz.? As far as I can tell, the two antennas are identical except
> >>> for the size of the tuning capacitor.? Each consists of a 3 foot (91
> >>> cm) diameter loop made of aluminum tubing and a plastic housing that
> >>> contains the tuning capacitor, motor, and coupling loop.? No control
> >>> cable is required since the control voltage is sent from the control
> >>> box in the shack to the motor in the antenna via the coaxial cable.
> >>>
> >>> Before I purchase one of these I wanted to get an idea of the
> >>> efficiency of such a small loop.? MFJ is silent on the subject so I
> >>> did my own calculations.? The calculations and results are on a
> >>> 1-page document that I uploaded to Dropbox and can be downloaded here:
> >>>
> >>> https://www.dropbox.com/s/l8mv67cjrck2ssn/MFJ-1786-1788.pdf?dl=0
> >>>
> >>> My calculations are based on the assumption that the efficiency of
> >>> the MFJ antennas is similar to the (no longer manufactured) AEA
> >>> Isoloop (my reasoning for that is in the document) and that AEA's
> >>> specification of 72% efficiency at 14 MHz is correct.? From that
> >>> number I can calculate the efficiency and gain on all the other bands.
> >>>
> >>> If you don't want to download the document, here is a summary of the
> >>> results:
> >>>
> >>> Freq????? Eff????? Gain with respect to a half-wave dipole
> >>> MHz????? dB????? dBd
> >>> 7.0??????? -7.3??? -7.7
> >>> 10.1? ? ? -3.5??? -3.9
> >>> 14.0?? ?? -1.4??? -1.8
> >>> 18.068? -0.6??? -1.0
> >>> 21.0?? ?? -0.4??? -0.8
> >>> 24.89??? -0.2??? -0.6
> >>> 28.0????? -0.15? -0.5
> >>>
> >>> I'd be interested in any comments people may have on the accuracy of
> >>> my assumptions and calculations in the document.
> >>>
> >>> Alan N1AL
>
>
>
> ------------------------------
>
> Message: 14
> Date: Tue, 19 Jan 2021 23:37:59 +0000 (UTC)
> From: Louandzip <louandzip at yahoo.com>
> Cc: Elecraft Reflector <elecraft at mailman.qth.net>
> Subject: Re: [Elecraft] Efficiency of MFJ remotely-tuned loop antennas
> Message-ID: <156673609.751378.1611099479734 at mail.yahoo.com>
> Content-Type: text/plain; charset=UTF-8
>
> Certainly don't want to throw away power in wasted heat, but when I turn
> down my 200W rig to 5W for QRP, it's still useful and that's 16 dB down.
>
> With ant restrictions, I'm looking at building a small horizontal loop for
> 6m.? It'd be a little more than 4' in circumference, 16" dia,? and the
> capacitor could be be two 4 cm diameter plates ~2mm apart. That should be
> reasonably easy to make relatively efficent as there are not a lot of
> plates that need to be connected with very low resistance.? I calculate
> ~85% with 1/2" copper.? Should be good for 200W.? I'd orient it
> horizontally for horizontal polarization (weak sigs) and local noise
> rejection.
>
> I have a squalo made from a lawn chair, but technically that's not a small
> loop and a little big to be stealth.
>
> On Tuesday, January 19, 2021, 3:58:09 PM MST, Alan Bloom <
> n1al at sonic.net> wrote:
>
> I've been convinced that AEA's specification of 72% efficiency for the
> Isoloop at 14 MHz is too high, certainly too high for the MFJ antennas.?
> So I re-did the calculations using the 59% efficiency figure calculated
> below.? The new results can be downloaded here:
>
> <https://www.dropbox.com/s/ve1v49b3gjvmt64/MFJ-1786-1788_2.pdf?dl=0>
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