[R-390] R-390 Digest, Vol 180, Issue 14
Gary Biasini
gary.biasini at shaw.ca
Sat Apr 13 13:16:43 EDT 2019
Jose,
You may wish to surf on over to
http://www.dashdist.com/1u2u/R-390A/LCD/LCD.php
For some hints.
Regards,Gary
Gary I. Biasini
On Sat, Apr 13, 2019 at 2:01 AM -0600, "jm" <josemic at gmail.com> wrote:
Hi fellows
I use a frequency meter with my tube receivers. Every set has its
peculiarity but until now I have managed with the HQ-180, Transoceanic
(transistors) and Hallicrafters sx99.
The trick is to locate the oscillator signal, offset the IF and the thing
works.
But... what about the 390? variable IF, lots of crystals. I have to confess
that I'm lost.
Is there an easy way to connect the frequency meter in a point in which the
oscillator signal could be found for all mhz positions?. What would be the
IF value to offset ?
I know that the challenge in this receiver is to obtain the maximun
sensitivity and precision via calibration but that's not my league yet and
meanwhile I think that a good solution is the frequency meter.
Regards and sorry for a beginner's question.
Jose
EA8DCP
El vie., 12 abr. 2019 a las 13:52, escribió:
> Send R-390 mailing list submissions to
> r-390 at mailman.qth.net
>
> To subscribe or unsubscribe via the World Wide Web, visit
> http://mailman.qth.net/mailman/listinfo/r-390
> or, via email, send a message with subject or body 'help' to
> r-390-request at mailman.qth.net
>
> You can reach the person managing the list at
> r-390-owner at mailman.qth.net
>
> When replying, please edit your Subject line so it is more specific
> than "Re: Contents of R-390 digest..."
>
>
> Today's Topics:
>
> 1. IF Transformer, alignment and performance (Tisha Hayes)
> 2. Re: IF Transformer, alignment and performance (Alan Victor)
> 3. Antenna trimmer (fdigio1)
> 4. Re: Antenna trimmer (Larry H)
> 5. R: Antenna trimmer (fdigio1 at gmail.com)
>
6. Frequency counter on r390a
>
>
> ----------------------------------------------------------------------
>
> Message: 1
> Date: Wed, 10 Apr 2019 15:19:40 -0500
> From: Tisha Hayes
> To: R390A
> Subject: [R-390] IF Transformer, alignment and performance
> Message-ID:
> cJYMPQWZG4pSWHnXaDX+kBuzBwz3kS5zww at mail.gmail.com>
> Content-Type: text/plain; charset="UTF-8"
>
> I have been lurking for quite a while, I continue to travel extensively and
> rarely get to fire up my radios;
>
> But on to sensitivity;
>
> We know what S/N (signal to noise ratio) and receiver selectivity has
> probably even more to do with receiver performance than just sensitivity,
> expressed as either RSL in dBm, uV or S-units.
> Once you get to the point where you are between 3 and 0.5 uV sensitivity
> and you are still wanting more you find yourself chasing after ways to
> improve selectivity.
> I did a few things to improve selectivity; since I was not worried about
> ESSB or wideband audio quality for BCB or SWL listening (I primarily listen
> to SSB or CW) I went after the stagger-tuning on the IF
> Going with a conventional alignment of the stages instead of an offset made
> the radio more selective. Building a 12 KHz wide roofing filter between the
> RF and IF decks helped as well.
> Fortunately I live in a radio-quiet area where across most bands the
> background noise levels are -110 to -115 dBm (S2-S3) when there aren't
> thunderstorm crashes I can dig out some good ones off of the tail end of a
> 1600' beverage.
>
> Trying to do better than -110 to -112 dBm RSSI required the use of a
> Faraday cage and constantly swapping good tubes for good tubes to find the
> quietest one. It reverted to black-magic and I wanted to do blood
> sacrifices and scatter chicken bones for better results. That is when I put
> a stop to that fools-pursuit.
>
> *Ms. Tisha Hayes, AA4HA*
>
> *Senior Engineer, 4RF*
>
>
> ------------------------------
>
> Message: 2
> Date: Wed, 10 Apr 2019 14:47:58 -0700
> From: Alan Victor
> To: Tisha Hayes
> Cc: R390A
> Subject: Re: [R-390] IF Transformer, alignment and performance
> Message-ID:
> LsG2bpH5vChYt9Rqz_JWX7LxZA at mail.gmail.com>
> Content-Type: text/plain; charset="UTF-8"
>
> So Tisha,
>
> As a bench level data point for the receiver system you describe, what is
> your ON BENCH 50 ohm signal level sensitivity measure? I assume for the
> same S/N ratio you address hooked up to your receive antenna (nice), that
> it is in excess of -112 dBm?
>
> Thanks, Alan W4AMV
>
>
> On Wed, Apr 10, 2019 at 1:20 PM Tisha Hayes wrote:
>
> > I have been lurking for quite a while, I continue to travel extensively
> and
> > rarely get to fire up my radios;
> >
> > But on to sensitivity;
> >
> > We know what S/N (signal to noise ratio) and receiver selectivity has
> > probably even more to do with receiver performance than just sensitivity,
> > expressed as either RSL in dBm, uV or S-units.
> > Once you get to the point where you are between 3 and 0.5 uV sensitivity
> > and you are still wanting more you find yourself chasing after ways to
> > improve selectivity.
> > I did a few things to improve selectivity; since I was not worried about
> > ESSB or wideband audio quality for BCB or SWL listening (I primarily
> listen
> > to SSB or CW) I went after the stagger-tuning on the IF
> > Going with a conventional alignment of the stages instead of an offset
> made
> > the radio more selective. Building a 12 KHz wide roofing filter between
> the
> > RF and IF decks helped as well.
> > Fortunately I live in a radio-quiet area where across most bands the
> > background noise levels are -110 to -115 dBm (S2-S3) when there aren't
> > thunderstorm crashes I can dig out some good ones off of the tail end of
> a
> > 1600' beverage.
> >
> > Trying to do better than -110 to -112 dBm RSSI required the use of a
> > Faraday cage and constantly swapping good tubes for good tubes to find
> the
> > quietest one. It reverted to black-magic and I wanted to do blood
> > sacrifices and scatter chicken bones for better results. That is when I
> put
> > a stop to that fools-pursuit.
> >
> > *Ms. Tisha Hayes, AA4HA*
> >
> > *Senior Engineer, 4RF*
> > ______________________________________________________________
> > 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: Thu, 11 Apr 2019 08:02:40 +0200
> From: fdigio1
> To: R-390 at mailman.qth.net
> Subject: [R-390] Antenna trimmer
> Message-ID: <5caed883.1c69fb81.aeae8.f9f5 at mx.google.com>
> Content-Type: text/plain; charset=utf-8
>
> Hi guys, the restoration of my R-390A goes on.?All the missing screws,
> lock and flat washer are on their position. All of wrong type are been
> replaced with the correct one, even the missing green screws.?Every RF deck
> gear is cleaned and lubed.?I have some issues with the antenna trimmer.?1)
> the red dot is vanished. Which is the right alignment? Full, minimum, half
> capacitance??2)I suspect it is contaminated by oil or grease. I tried to
> remove its cover from the bottom, but the 3 wires are too short to let me
> expose the dual section variable capacitor and their solders to the rotary
> switch are difficult to reach.I could remove the worm gear on top, but I am
> unsure in which direction to push the pin.?Any idea??Best regards,
> Francesco - IN3XZP?Inviato da smartphone Samsung Galaxy.
>
> ------------------------------
>
> Message: 4
> Date: Fri, 12 Apr 2019 02:09:32 -0700
> From: Larry H
> To: fdigio1
> Cc: R-390 Forum
> Subject: Re: [R-390] Antenna trimmer
> Message-ID:
> <
> CAOSJ_nvWoDafoHp-9EaC6OHhUMxtormOephE32UGj5KCuCwTrA at mail.gmail.com>
> Content-Type: text/plain; charset="UTF-8"
>
> Hi Francesco, Glad you are making progress on your A.
>
> When the Ant Trim knob is straight up, the cap should be at it's 1/2 way
> point. There was a discussion about the pin on Wed, Jun 20, 2018, 4:20
> AM. Take a look.
>
> Regards, Larry
>
>
>
> On Wed, Apr 10, 2019 at 11:02 PM fdigio1 wrote:
>
> > Hi guys, the restoration of my R-390A goes on. All the missing screws,
> > lock and flat washer are on their position. All of wrong type are been
> > replaced with the correct one, even the missing green screws. Every RF
> deck
> > gear is cleaned and lubed. I have some issues with the antenna trimmer.
> 1)
> > the red dot is vanished. Which is the right alignment? Full, minimum,
> half
> > capacitance? 2)I suspect it is contaminated by oil or grease. I tried to
> > remove its cover from the bottom, but the 3 wires are too short to let me
> > expose the dual section variable capacitor and their solders to the
> rotary
> > switch are difficult to reach.I could remove the worm gear on top, but I
> am
> > unsure in which direction to push the pin. Any idea? Best regards,
> > Francesco - IN3XZP Inviato da smartphone Samsung Galaxy.
> > ______________________________________________________________
> > 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: 5
> Date: Fri, 12 Apr 2019 14:52:19 +0200
> From:
> To: "'Larry H'"
> Cc: 'R-390 Forum'
> Subject: [R-390] R: Antenna trimmer
> Message-ID: <[email protected]>
> Content-Type: text/plain; charset="utf-8"
>
> Thank you Larry for the kind answer.
>
> I?ll go and check the messages.
>
>
>
> This morning I have made the modification at R523 as described by David
> Wise.
>
> I installed a new Allen Bradley 100 Ohm potentiometer and, at the moment,
> a 8.2 Ohm resistor for R537.
>
> When some resistor I ordered will arrive, I?ll change its value to 6.8 Ohm.
>
> This upgrade is awesome! No problem to calibrate the Carrier Level Meter.
> What a smooth adjustment!!!
>
> I put 100?V into the antenna input and adjusted R523 for 100dB on the
> meter,
>
> as written on ?The Almost Ultimate R390A Upgrade Schematics? of Perry
> Sandeen (thank you Perry for you
>
> invaluable help). I checked the meter with 10, 20, 30?.80, 90 ?V and the
> meter indicates
>
> 10, 20, 30?.80, 90 dB!!! Fantastic!!!!
>
> Thank you guys!
>
>
>
> Francesco Di Giovanni - IN3XZP
>
>
>
>
>
> Da: Larry H
> Inviato: venerd? 12 aprile 2019 11:10
> A: fdigio1
> Cc: R-390 Forum
> Oggetto: Re: [R-390] Antenna trimmer
>
>
>
> Hi Francesco, Glad you are making progress on your A.
>
>
>
> When the Ant Trim knob is straight up, the cap should be at it's 1/2 way
> point. There was a discussion about the pin on Wed, Jun 20, 2018, 4:20
> AM. Take a look.
>
>
>
> Regards, Larry
>
>
>
>
>
>
>
> On Wed, Apr 10, 2019 at 11:02 PM fdigio1 fdigio1 at gmail.com> > wrote:
>
> Hi guys, the restoration of my R-390A goes on. All the missing screws,
> lock and flat washer are on their position. All of wrong type are been
> replaced with the correct one, even the missing green screws. Every RF deck
> gear is cleaned and lubed. I have some issues with the antenna trimmer. 1)
> the red dot is vanished. Which is the right alignment? Full, minimum, half
> capacitance? 2)I suspect it is contaminated by oil or grease. I tried to
> remove its cover from the bottom, but the 3 wires are too short to let me
> expose the dual section variable capacitor and their solders to the rotary
> switch are difficult to reach.I could remove the worm gear on top, but I am
> unsure in which direction to push the pin. Any idea? Best regards,
> Francesco - IN3XZP Inviato da smartphone Samsung Galaxy.
> ______________________________________________________________
> 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
> R-390 at mailman.qth.net
> http://mailman.qth.net/mailman/listinfo/r-390
>
>
> End of R-390 Digest, Vol 180, Issue 14
> **************************************
>
Libre
de virus. www.avast.com
<#DAB4FAD8-2DD7-40BB-A1B8-4E2AA1F9FDF2>
______________________________________________________________
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
Hi fellows
I use a frequency meter with my tube receivers. Every set has its
peculiarity but until now I have managed with the HQ-180, Transoceanic
(transistors) and Hallicrafters sx99.
The trick is to locate the oscillator signal, offset the IF and the thing
works.
But... what about the 390? variable IF, lots of crystals. I have to confess
that I'm lost.
Is there an easy way to connect the frequency meter in a point in which the
oscillator signal could be found for all mhz positions?. What would be the
IF value to offset ?
I know that the challenge in this receiver is to obtain the maximun
sensitivity and precision via calibration but that's not my league yet and
meanwhile I think that a good solution is the frequency meter.
Regards and sorry for a beginner's question.
Jose
EA8DCP
El vie., 12 abr. 2019 a las 13:52, <r-390-request at mailman.qth.net> escribió:
> Send R-390 mailing list submissions to
> r-390 at mailman.qth.net
>
> To subscribe or unsubscribe via the World Wide Web, visit
> http://mailman.qth.net/mailman/listinfo/r-390
> or, via email, send a message with subject or body 'help' to
> r-390-request at mailman.qth.net
>
> You can reach the person managing the list at
> r-390-owner at mailman.qth.net
>
> When replying, please edit your Subject line so it is more specific
> than "Re: Contents of R-390 digest..."
>
>
> Today's Topics:
>
> 1. IF Transformer, alignment and performance (Tisha Hayes)
> 2. Re: IF Transformer, alignment and performance (Alan Victor)
> 3. Antenna trimmer (fdigio1)
> 4. Re: Antenna trimmer (Larry H)
> 5. R: Antenna trimmer (fdigio1 at gmail.com)
>
6. Frequency counter on r390a
>
>
> ----------------------------------------------------------------------
>
> Message: 1
> Date: Wed, 10 Apr 2019 15:19:40 -0500
> From: Tisha Hayes <tisha.hayes at gmail.com>
> To: R390A <r-390 at mailman.qth.net>
> Subject: [R-390] IF Transformer, alignment and performance
> Message-ID:
> <CAACTF108aef-UC=+
> cJYMPQWZG4pSWHnXaDX+kBuzBwz3kS5zww at mail.gmail.com>
> Content-Type: text/plain; charset="UTF-8"
>
> I have been lurking for quite a while, I continue to travel extensively and
> rarely get to fire up my radios;
>
> But on to sensitivity;
>
> We know what S/N (signal to noise ratio) and receiver selectivity has
> probably even more to do with receiver performance than just sensitivity,
> expressed as either RSL in dBm, uV or S-units.
> Once you get to the point where you are between 3 and 0.5 uV sensitivity
> and you are still wanting more you find yourself chasing after ways to
> improve selectivity.
> I did a few things to improve selectivity; since I was not worried about
> ESSB or wideband audio quality for BCB or SWL listening (I primarily listen
> to SSB or CW) I went after the stagger-tuning on the IF
> Going with a conventional alignment of the stages instead of an offset made
> the radio more selective. Building a 12 KHz wide roofing filter between the
> RF and IF decks helped as well.
> Fortunately I live in a radio-quiet area where across most bands the
> background noise levels are -110 to -115 dBm (S2-S3) when there aren't
> thunderstorm crashes I can dig out some good ones off of the tail end of a
> 1600' beverage.
>
> Trying to do better than -110 to -112 dBm RSSI required the use of a
> Faraday cage and constantly swapping good tubes for good tubes to find the
> quietest one. It reverted to black-magic and I wanted to do blood
> sacrifices and scatter chicken bones for better results. That is when I put
> a stop to that fools-pursuit.
>
> *Ms. Tisha Hayes, AA4HA*
>
> *Senior Engineer, 4RF*
>
>
> ------------------------------
>
> Message: 2
> Date: Wed, 10 Apr 2019 14:47:58 -0700
> From: Alan Victor <amvictor at ncsu.edu>
> To: Tisha Hayes <tisha.hayes at gmail.com>
> Cc: R390A <r-390 at mailman.qth.net>
> Subject: Re: [R-390] IF Transformer, alignment and performance
> Message-ID:
> <CAO-B_TeA9bbC7SKcXe6qZWp=
> LsG2bpH5vChYt9Rqz_JWX7LxZA at mail.gmail.com>
> Content-Type: text/plain; charset="UTF-8"
>
> So Tisha,
>
> As a bench level data point for the receiver system you describe, what is
> your ON BENCH 50 ohm signal level sensitivity measure? I assume for the
> same S/N ratio you address hooked up to your receive antenna (nice), that
> it is in excess of -112 dBm?
>
> Thanks, Alan W4AMV
>
>
> On Wed, Apr 10, 2019 at 1:20 PM Tisha Hayes <tisha.hayes at gmail.com> wrote:
>
> > I have been lurking for quite a while, I continue to travel extensively
> and
> > rarely get to fire up my radios;
> >
> > But on to sensitivity;
> >
> > We know what S/N (signal to noise ratio) and receiver selectivity has
> > probably even more to do with receiver performance than just sensitivity,
> > expressed as either RSL in dBm, uV or S-units.
> > Once you get to the point where you are between 3 and 0.5 uV sensitivity
> > and you are still wanting more you find yourself chasing after ways to
> > improve selectivity.
> > I did a few things to improve selectivity; since I was not worried about
> > ESSB or wideband audio quality for BCB or SWL listening (I primarily
> listen
> > to SSB or CW) I went after the stagger-tuning on the IF
> > Going with a conventional alignment of the stages instead of an offset
> made
> > the radio more selective. Building a 12 KHz wide roofing filter between
> the
> > RF and IF decks helped as well.
> > Fortunately I live in a radio-quiet area where across most bands the
> > background noise levels are -110 to -115 dBm (S2-S3) when there aren't
> > thunderstorm crashes I can dig out some good ones off of the tail end of
> a
> > 1600' beverage.
> >
> > Trying to do better than -110 to -112 dBm RSSI required the use of a
> > Faraday cage and constantly swapping good tubes for good tubes to find
> the
> > quietest one. It reverted to black-magic and I wanted to do blood
> > sacrifices and scatter chicken bones for better results. That is when I
> put
> > a stop to that fools-pursuit.
> >
> > *Ms. Tisha Hayes, AA4HA*
> >
> > *Senior Engineer, 4RF*
> > ______________________________________________________________
> > 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: Thu, 11 Apr 2019 08:02:40 +0200
> From: fdigio1 <fdigio1 at gmail.com>
> To: R-390 at mailman.qth.net
> Subject: [R-390] Antenna trimmer
> Message-ID: <5caed883.1c69fb81.aeae8.f9f5 at mx.google.com>
> Content-Type: text/plain; charset=utf-8
>
> Hi guys, the restoration of my R-390A goes on.?All the missing screws,
> lock and flat washer are on their position. All of wrong type are been
> replaced with the correct one, even the missing green screws.?Every RF deck
> gear is cleaned and lubed.?I have some issues with the antenna trimmer.?1)
> the red dot is vanished. Which is the right alignment? Full, minimum, half
> capacitance??2)I suspect it is contaminated by oil or grease. I tried to
> remove its cover from the bottom, but the 3 wires are too short to let me
> expose the dual section variable capacitor and their solders to the rotary
> switch are difficult to reach.I could remove the worm gear on top, but I am
> unsure in which direction to push the pin.?Any idea??Best regards,
> Francesco - IN3XZP?Inviato da smartphone Samsung Galaxy.
>
> ------------------------------
>
> Message: 4
> Date: Fri, 12 Apr 2019 02:09:32 -0700
> From: Larry H <larry41gm at gmail.com>
> To: fdigio1 <fdigio1 at gmail.com>
> Cc: R-390 Forum <R-390 at mailman.qth.net>
> Subject: Re: [R-390] Antenna trimmer
> Message-ID:
> <
> CAOSJ_nvWoDafoHp-9EaC6OHhUMxtormOephE32UGj5KCuCwTrA at mail.gmail.com>
> Content-Type: text/plain; charset="UTF-8"
>
> Hi Francesco, Glad you are making progress on your A.
>
> When the Ant Trim knob is straight up, the cap should be at it's 1/2 way
> point. There was a discussion about the pin on Wed, Jun 20, 2018, 4:20
> AM. Take a look.
>
> Regards, Larry
>
>
>
> On Wed, Apr 10, 2019 at 11:02 PM fdigio1 <fdigio1 at gmail.com> wrote:
>
> > Hi guys, the restoration of my R-390A goes on. All the missing screws,
> > lock and flat washer are on their position. All of wrong type are been
> > replaced with the correct one, even the missing green screws. Every RF
> deck
> > gear is cleaned and lubed. I have some issues with the antenna trimmer.
> 1)
> > the red dot is vanished. Which is the right alignment? Full, minimum,
> half
> > capacitance? 2)I suspect it is contaminated by oil or grease. I tried to
> > remove its cover from the bottom, but the 3 wires are too short to let me
> > expose the dual section variable capacitor and their solders to the
> rotary
> > switch are difficult to reach.I could remove the worm gear on top, but I
> am
> > unsure in which direction to push the pin. Any idea? Best regards,
> > Francesco - IN3XZP Inviato da smartphone Samsung Galaxy.
> > ______________________________________________________________
> > 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: 5
> Date: Fri, 12 Apr 2019 14:52:19 +0200
> From: <fdigio1 at gmail.com>
> To: "'Larry H'" <larry41gm at gmail.com>
> Cc: 'R-390 Forum' <R-390 at mailman.qth.net>
> Subject: [R-390] R: Antenna trimmer
> Message-ID: <[email protected]>
> Content-Type: text/plain; charset="utf-8"
>
> Thank you Larry for the kind answer.
>
> I?ll go and check the messages.
>
>
>
> This morning I have made the modification at R523 as described by David
> Wise.
>
> I installed a new Allen Bradley 100 Ohm potentiometer and, at the moment,
> a 8.2 Ohm resistor for R537.
>
> When some resistor I ordered will arrive, I?ll change its value to 6.8 Ohm.
>
> This upgrade is awesome! No problem to calibrate the Carrier Level Meter.
> What a smooth adjustment!!!
>
> I put 100?V into the antenna input and adjusted R523 for 100dB on the
> meter,
>
> as written on ?The Almost Ultimate R390A Upgrade Schematics? of Perry
> Sandeen (thank you Perry for you
>
> invaluable help). I checked the meter with 10, 20, 30?.80, 90 ?V and the
> meter indicates
>
> 10, 20, 30?.80, 90 dB!!! Fantastic!!!!
>
> Thank you guys!
>
>
>
> Francesco Di Giovanni - IN3XZP
>
>
>
>
>
> Da: Larry H <larry41gm at gmail.com>
> Inviato: venerd? 12 aprile 2019 11:10
> A: fdigio1 <fdigio1 at gmail.com>
> Cc: R-390 Forum <R-390 at mailman.qth.net>
> Oggetto: Re: [R-390] Antenna trimmer
>
>
>
> Hi Francesco, Glad you are making progress on your A.
>
>
>
> When the Ant Trim knob is straight up, the cap should be at it's 1/2 way
> point. There was a discussion about the pin on Wed, Jun 20, 2018, 4:20
> AM. Take a look.
>
>
>
> Regards, Larry
>
>
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> On Wed, Apr 10, 2019 at 11:02 PM fdigio1 <fdigio1 at gmail.com <mailto:
> fdigio1 at gmail.com> > wrote:
>
> Hi guys, the restoration of my R-390A goes on. All the missing screws,
> lock and flat washer are on their position. All of wrong type are been
> replaced with the correct one, even the missing green screws. Every RF deck
> gear is cleaned and lubed. I have some issues with the antenna trimmer. 1)
> the red dot is vanished. Which is the right alignment? Full, minimum, half
> capacitance? 2)I suspect it is contaminated by oil or grease. I tried to
> remove its cover from the bottom, but the 3 wires are too short to let me
> expose the dual section variable capacitor and their solders to the rotary
> switch are difficult to reach.I could remove the worm gear on top, but I am
> unsure in which direction to push the pin. Any idea? Best regards,
> Francesco - IN3XZP Inviato da smartphone Samsung Galaxy.
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>
> End of R-390 Digest, Vol 180, Issue 14
> **************************************
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