[R-390] R-390 Digest, Vol 253, Issue 1

Sun Aug 3 01:43:05 EDT 2025

I Would Surmise One of the caps has changed value .........Probablly the  1600Pf.
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Subject: R-390 Digest, Vol 253, Issue 1

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Today's Topics:

   1. R390 IF deck 70j-3/Z502 BFO interesting issue- (Renee K6FSB)
   2. Re: R390 IF deck 70j-3/Z502 BFO interesting issue- (Barry)
   3. Re: R390 IF deck 70j-3/Z502 BFO interesting issue-
      (Jacques Fortin)

----------------------------------------------------------------------

Message: 1
Date: Fri, 1 Aug 2025 12:27:54 -0700
From: Renee K6FSB <k6fsb.1 at gmail.com>
To: R-390 mail out <r-390 at mailman.qth.net>
Subject: [R-390] R390 IF deck 70j-3/Z502 BFO interesting issue-
Message-ID: <9478f10d-b30a-54cd-8285-955827710737 at gmail.com>
Content-Type: text/plain; charset=utf-8; format=flowed

R390 70j-3 BFO has an interesting issue- one I have not seen before. Z502
tunes from 463 to 479 kc, stable and good signal per spectrum analyzer.
checked all external parts- all withing spec, opened unit, all parts
present ( someone has opened it the past seal was broken). "Things" look ok.
moving core appears to be intact does not appear to have been tampered.
Before I go any further anyone with thoughts?
- any known loss of permeability of the core? possibly due to temp?
caps internally go "bad" 1600pf, 50pf NPO, 50pf N600.......there is not
much in there as per schematics...simple hartely osc.
the core does not go completely to the end of the form, maybe couple mm
from end. but does cover the coil length.
How do get the core out for inspection? I saw where someone else had
epoxied one back together.....but no notes on full disassembly.
So....If it is non repairable...anyone have a 70j-1 or a -3 available?
Ren?e, K6FSB

------------------------------

Message: 2
Date: Fri, 1 Aug 2025 18:51:03 -0400 (EDT)
From: Barry <n4buq at knology.net>
To: k6fsb <k6fsb at arrl.net>
Cc: R-390 Mailing List <r-390 at mailman.qth.net>
Subject: Re: [R-390] R390 IF deck 70j-3/Z502 BFO interesting issue-
Message-ID:
        <1276552154.12877738.1754088663041.JavaMail.zimbra at knology.net>
Content-Type: text/plain; charset=utf-8

Hi Ren?e,

I'm not sure I follow this.  Are you saying it will _only_ tune from 463 to 479 kc?

Barry - N4BUQ

> R390 70j-3 BFO has an interesting issue- one I have not seen before. Z502
> tunes from 463 to 479 kc, stable and good signal per spectrum analyzer.
> checked all external parts- all withing spec, opened unit, all parts
> present ( someone has opened it the past seal was broken). "Things" look ok.
> moving core appears to be intact does not appear to have been tampered.
> Before I go any further anyone with thoughts?
> - any known loss of permeability of the core? possibly due to temp?
> caps internally go "bad" 1600pf, 50pf NPO, 50pf N600.......there is not
> much in there as per schematics...simple hartely osc.
> the core does not go completely to the end of the form, maybe couple mm
> from end. but does cover the coil length.
> How do get the core out for inspection? I saw where someone else had
> epoxied one back together.....but no notes on full disassembly.
> So....If it is non repairable...anyone have a 70j-1 or a -3 available?
> Ren?e, K6FSB
> ______________________________________________________________
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------------------------------

Message: 3
Date: Fri, 1 Aug 2025 22:35:58 -0400
From: Jacques Fortin <jacques.f at videotron.ca>
To: Barry <n4buq at knology.net>
Cc: R-390 Mailing List <r-390 at mailman.qth.net>, k6fsb <k6fsb at arrl.net>
Subject: Re: [R-390] R390 IF deck 70j-3/Z502 BFO interesting issue-
Message-ID: <666629B5-84D3-402D-BE69-F42AF15F8EE6 at videotron.ca>
Content-Type: text/plain; charset=utf-8

Like one of the 50pf is open?

Jacques, VE2JFE in Montr?al (more or less).

Le 1 ao?t 2025 ? 18:59, Barry <n4buq at knology.net> a ?crit :

?Hi Ren?e,

I'm not sure I follow this.  Are you saying it will _only_ tune from 463 to 479 kc?

Barry - N4BUQ

> R390 70j-3 BFO has an interesting issue- one I have not seen before. Z502
> tunes from 463 to 479 kc, stable and good signal per spectrum analyzer.
> checked all external parts- all withing spec, opened unit, all parts
> present ( someone has opened it the past seal was broken). "Things" look ok.
> moving core appears to be intact does not appear to have been tampered.
> Before I go any further anyone with thoughts?
> - any known loss of permeability of the core? possibly due to temp?
> caps internally go "bad" 1600pf, 50pf NPO, 50pf N600.......there is not
> much in there as per schematics...simple hartely osc.
> the core does not go completely to the end of the form, maybe couple mm
> from end. but does cover the coil length.
> How do get the core out for inspection? I saw where someone else had
> epoxied one back together.....but no notes on full disassembly.
> So....If it is non repairable...anyone have a 70j-1 or a -3 available?
> Ren?e, K6FSB
> ______________________________________________________________
> 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
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