[R-390] R-390 Digest, Vol 180, Issue 36

sigmapert sigmapert at gmx.de
Mon Apr 29 15:03:57 EDT 2019 

Hi jm,

the balun transforms 50 Ohms unbalanced to about 130 Ohms balanced. But most important is RF noise
cancellation (CMR).

The balun shown in your photo is much too large and thus has high (stray) losses (insertion loss).
Baluns at the receiver front-end should be as tiny as possible.

The enclosed photo shows an adapter containing a tiny balun with low loss (MiniCircuits). The second
photo depicts, charts a) insertion loss, b) CMR versus input frequency (0.5 - 30 Mc), c) both as
table.

sigmapert

am Montag, 29. April 2019 um 18:39 schrieben Sie:

> Re. Antenna connection

> Hi guys!

> I have done some experiments with the antenna connectors in the r390a.

> First of all, I have followed the extended and ‘official line’
>  instructions about the use of the balanced connector, grounding one of the
> terminals being the antenna connected to the other through a capacitor. My
> antenna is a long wire one fed with coax and pl259 connector.

> My questions:

> 1.       Sometimes I plug the antenna to the unbalanced connexion and I
> think that it is a slightly stronger signal.   Has it any sense? If so, why
> the common belief is the connection  to the balanced terminals? The
> military manuals state that the unbalanced connector is intended for whip
> and long wire specifically.



> 2.       I have found on ebay one r390a for sale. The seller mentions one
> mod in which the antenna is connected through a toroidal 4:1 balun instead
> of a capacitor (photo attached).  He claims that ‘matches and balances the
> 100+ohm receiver input to 50 ohm coax, grounding out household RF noise
> picked up by the coax shield. Popular adapters which directly connect the
> coax shield to one side of the balanced input let this noise in, and also
> cause signal loss due to impedance mismatch’.

> Has anyone tried this way?

> Many thanks and regards

> Jose Isasa EA8DCP

> El lun., 29 abr. 2019 a las 15:39, <r-390-request at mailman.qth.net> escribió:

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>> Today's Topics:
>>
>>    1. Meeting up with other list members at Entelec (Tisha Hayes)
>>    2. Re: Meeting up with other list members at Entelec (Tom Frobase)
>>    3. Re: Meeting up with other list members at Entelec (John Flood)
>>    4. TB SIG 319 (David Hallam)
>>
>>
>> ----------------------------------------------------------------------
>>
>> Message: 1
>> Date: Sat, 27 Apr 2019 13:33:19 -0500
>> From: Tisha Hayes <tisha.hayes at gmail.com>
>> To: R390A <r-390 at mailman.qth.net>
>> Subject: [R-390] Meeting up with other list members at Entelec
>> Message-ID:
>>         <
>> CAACTF11wT0joY2c-mySiqTATV1aUQMFgBQpaY3N0K1Y8f7ySZg at mail.gmail.com>
>> Content-Type: text/plain; charset="UTF-8"
>>
>> It was surprising to have this guy walk up to our booth at Entelec in
>> Houston and start up a conversation with "so, does your company make the
>> 390 model?"
>>
>> I was instantly confused, I asked about three times in a row what he was
>> asking about; My personal radio hobby so rarely collides with my
>> professional life that it just did not compute. Finally with my bad eyes I
>> was able to read his name... Tom Frobase" and it still took a second to
>> click in my brain... then the conversation made sense.
>>
>> Tom had set up a table in a back corner of the convention hall with a
>> BC-348, Heathkit transmitter, CW key, box of QSL cards and a very nice
>> little tribute to an SK who was a past member of the Entelec board. Entelec
>> is an association for oil and gas communications folks. Our company was
>> there with a booth to present our radios, I was there to do five different
>> sessions over the three days. Tom happened to hear my speaking at a
>> vendor-shootout discussing the merits of narrowband radio and the Internet
>> of Things.. He teased me because I commented about how the people who write
>> standards are often divorced from the reality of making systems work or
>> supporting them in the field.
>>
>> When I made it back to the booth I was quizzed "how do you know Tom Frobase
>> from Boardwalk?"  I had to explain about R-390A's and boat anchors and that
>> just classified me even further in to the "weird radio chick" category.
>>
>> Later that day Tom swung by as I was sitting on the floor, taking about
>> booth furniture. He always gets me at the most inconvenient moments!
>>
>> But it was nice to see another boat anchor enthusiast. I am fortunate to
>> work for a company filled with electrical engineers who are also hams and
>> radio nerds.
>>
>> *Ms. Tisha Hayes, AA4HA*
>>
>>
>> ------------------------------
>>
>> Message: 2
>> Date: Sat, 27 Apr 2019 13:47:27 -0500
>> From: Tom Frobase <tfrobase at gmail.com>
>> To: Tisha Hayes <tisha.hayes at gmail.com>
>> Cc: R390A <r-390 at mailman.qth.net>
>> Subject: Re: [R-390] Meeting up with other list members at Entelec
>> Message-ID:
>>         <
>> CABYVeFVD5ceNHzDjqnBV-hLjZ7WUiX3V2P50PDjDurM0pex-wg at mail.gmail.com>
>> Content-Type: text/plain; charset="UTF-8"
>>
>> Thank you for the nice comments.  It is not the first time this has
>> happened.  Several years ago at a vendor's office in the Boston area
>> and my phone started to ring, the ring tone was DE DE N3LLL in Morse
>> code.  When we took a break John Flood, N1JAF came over and introduced
>> himself.  Said he heard the callsign and recognized it from the 390
>> list. It has been interesting to me how many of the folks who really
>> get it, get their hands dirty doing what we do!  It really is a small
>> technical world ... Tom, N3LLL
>>
>>
>>
>> On Sat, Apr 27, 2019 at 1:34 PM Tisha Hayes <tisha.hayes at gmail.com> wrote:
>> >
>> > It was surprising to have this guy walk up to our booth at Entelec in
>> > Houston and start up a conversation with "so, does your company make the
>> > 390 model?"
>> >
>> > I was instantly confused, I asked about three times in a row what he was
>> > asking about; My personal radio hobby so rarely collides with my
>> > professional life that it just did not compute. Finally with my bad eyes
>> I
>> > was able to read his name... Tom Frobase" and it still took a second to
>> > click in my brain... then the conversation made sense.
>> >
>> > Tom had set up a table in a back corner of the convention hall with a
>> > BC-348, Heathkit transmitter, CW key, box of QSL cards and a very nice
>> > little tribute to an SK who was a past member of the Entelec board.
>> Entelec
>> > is an association for oil and gas communications folks. Our company was
>> > there with a booth to present our radios, I was there to do five
>> different
>> > sessions over the three days. Tom happened to hear my speaking at a
>> > vendor-shootout discussing the merits of narrowband radio and the
>> Internet
>> > of Things.. He teased me because I commented about how the people who
>> write
>> > standards are often divorced from the reality of making systems work or
>> > supporting them in the field.
>> >
>> > When I made it back to the booth I was quizzed "how do you know Tom
>> Frobase
>> > from Boardwalk?"  I had to explain about R-390A's and boat anchors and
>> that
>> > just classified me even further in to the "weird radio chick" category.
>> >
>> > Later that day Tom swung by as I was sitting on the floor, taking about
>> > booth furniture. He always gets me at the most inconvenient moments!
>> >
>> > But it was nice to see another boat anchor enthusiast. I am fortunate to
>> > work for a company filled with electrical engineers who are also hams and
>> > radio nerds.
>> >
>> > *Ms. Tisha Hayes, AA4HA*
>> > ______________________________________________________________
>> > R-390 mailing list
>> > Home: http://mailman.qth.net/mailman/listinfo/r-390
>> > Help: http://mailman.qth.net/mmfaq.htm
>> > Post: mailto:R-390 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: 3
>> Date: Sat, 27 Apr 2019 23:55:56 +0000 (UTC)
>> From: John Flood <kb1fqg at yahoo.com>
>> To: Tisha Hayes <tisha.hayes at gmail.com>, Tom Frobase
>>         <tfrobase at gmail.com>
>> Cc: R390A <r-390 at mailman.qth.net>
>> Subject: Re: [R-390] Meeting up with other list members at Entelec
>> Message-ID: <90573656.1306616.1556409356331 at mail.yahoo.com>
>> Content-Type: text/plain; charset=UTF-8
>>
>>  Interesting story Tom.? I remember? you stopping by my office.? Now the
>> last item on my bucket list is to meet Tisha!? Don't worry, I am a polite
>> stalker!? Also, Near-Fest is this coming weekend in Deerfield, NH
>> John Flood N1JAF
>>     On Saturday, April 27, 2019, 2:48:14 PM EDT, Tom Frobase <
>> tfrobase at gmail.com> wrote:
>>
>>  Thank you for the nice comments.? It is not the first time this has
>> happened.? Several years ago at a vendor's office in the Boston area
>> and my phone started to ring, the ring tone was DE DE N3LLL in Morse
>> code.? When we took a break John Flood, N1JAF came over and introduced
>> himself.? Said he heard the callsign and recognized it from the 390
>> list. It has been interesting to me how many of the folks who really
>> get it, get their hands dirty doing what we do!? It really is a small
>> technical world ... Tom, N3LLL
>>
>>
>>
>> On Sat, Apr 27, 2019 at 1:34 PM Tisha Hayes <tisha.hayes at gmail.com> wrote:
>> >
>> > It was surprising to have this guy walk up to our booth at Entelec in
>> > Houston and start up a conversation with "so, does your company make the
>> > 390 model?"
>> >
>> > I was instantly confused, I asked about three times in a row what he was
>> > asking about; My personal radio hobby so rarely collides with my
>> > professional life that it just did not compute. Finally with my bad eyes
>> I
>> > was able to read his name... Tom Frobase" and it still took a second to
>> > click in my brain... then the conversation made sense.
>> >
>> > Tom had set up a table in a back corner of the convention hall with a
>> > BC-348, Heathkit transmitter, CW key, box of QSL cards and a very nice
>> > little tribute to an SK who was a past member of the Entelec board.
>> Entelec
>> > is an association for oil and gas communications folks. Our company was
>> > there with a booth to present our radios, I was there to do five
>> different
>> > sessions over the three days. Tom happened to hear my speaking at a
>> > vendor-shootout discussing the merits of narrowband radio and the
>> Internet
>> > of Things.. He teased me because I commented about how the people who
>> write
>> > standards are often divorced from the reality of making systems work or
>> > supporting them in the field.
>> >
>> > When I made it back to the booth I was quizzed "how do you know Tom
>> Frobase
>> > from Boardwalk?"? I had to explain about R-390A's and boat anchors and
>> that
>> > just classified me even further in to the "weird radio chick" category.
>> >
>> > Later that day Tom swung by as I was sitting on the floor, taking about
>> > booth furniture. He always gets me at the most inconvenient moments!
>> >
>> > But it was nice to see another boat anchor enthusiast. I am fortunate to
>> > work for a company filled with electrical engineers who are also hams and
>> > radio nerds.
>> >
>> > *Ms. Tisha Hayes, AA4HA*
>> > ______________________________________________________________
>> > R-390 mailing list
>> > Home: http://mailman.qth.net/mailman/listinfo/r-390
>> > Help: http://mailman.qth.net/mmfaq.htm
>> > Post: mailto:R-390 at mailman.qth.net
>> >
>> > This list hosted by: http://www.qsl.net
>> > Please help support this email list: http://www.qsl.net/donate.html
>> ______________________________________________________________
>> R-390 mailing list
>> Home: http://mailman.qth.net/mailman/listinfo/r-390
>> Help: http://mailman.qth.net/mmfaq.htm
>> Post: mailto:R-390 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: 4
>> Date: Mon, 29 Apr 2019 14:39:08 +0000
>> From: David Hallam <collinsuser at outlook.com>
>> To: "r-390 at mailman.qth.net" <r-390 at mailman.qth.net>
>> Subject: [R-390] TB SIG 319
>> Message-ID:
>>         <
>> DM6PR15MB3211C241042F8AB69BA43AC2B5390 at DM6PR15MB3211.namprd15.prod.outlook.com
>> >
>>
>> Content-Type: text/plain; charset="utf-8"
>>
>> I don't know if everyone in this group is aware that there is an Army
>> Technical Bulletin TB SIG 319 Electronic Equipment Maintenance Kit
>> MK-288/URM for the signal generator AN/URM-25. This technical bulletin
>> covers among other things the 4 dummy loads with schematics used with
>> the AN/URM-25 for testing the R-390.? I used the schematics together
>> with some small die cast aluminum boxes to make my own.? I don't
>> remember where I got this, but I am sure an internet search would turn
>> it up.
>>
>> David
>> KW4DH
>>
>>
>> ------------------------------
>>
>> _______________________________________________
>> R-390 mailing list
>> R-390 at mailman.qth.net
>> http://mailman.qth.net/mailman/listinfo/r-390
>>
>>
>> End of R-390 Digest, Vol 180, Issue 36
>> **************************************
>>

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-- 
Mit freundlichen Grüßen
sigmapert
mailto:sigmapert at gmx.de
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