[R-390] BFO Hum Vol 150, Issue 26

Tue Oct 25 08:04:12 EDT 2016

Bernie,

I have seen the same phenomena occur in AM mode while listening via 
a Sherwood SE-3 Sync Detector. Imperceptible with the stock AM 
detector. Filament to cathode leakage in the PTO 6BA6, and a swap 
fixed it.

73 Bill N4LG

At 06:32 AM 10/25/2016, bernie nicholson wrote:
>Over the years I've had Probably in excess of 100    R390A and 
>R390  and R391  and 51J4  Rxs pass through my hands as I used to 
>buy them at the government surplus  auctions............ Re The 
>hum when you turn on the BFO , I have come across this a few times 
>, and its been  due to  Filament cathode leakage in either the BFO 
>or VFO 6BA6 s  which are in series with the 3TF7 regulator tube ,[ 
>REPLACING one of the  Tubes should Fix the Problem] regarding 
>covers I have a few spare original top and bottom covers , and a 
>spare IF strip, with filters  and  a quite large quantity of the 
>various size collars with the bristo screws , also I have a 
>surplus ''Progesteron''  VFO  and a quantity of NOS dual 450v caps 
>in the octal sockets , also a Spare power Transformer for a R390 
>NON A  receiver, Also A good 390A front panel ......  I probably 
>have lots more bits too if anyone is interested they can contact 
>me via  my  email address  regards  Bernie Nicholson ----- 
>Original Message ----- From: <r-390-request at mailman.qth.net>
>To: <r-390 at mailman.qth.net>
>Sent: Tuesday, October 25, 2016 10:13 AM
>Subject: R-390 Digest, Vol 150, Issue 26
>
>
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>>Today's Topics:
>>
>>   1. R-390A VFO/PTO Quality (Larry H)
>>   2. Receiver dust covers (Perry Sandeen)
>>   3. Re: Receiver dust covers (Al Parker)
>>   4. Re: bfo hum and s meter not on zero (kg2bz at comcast.net)
>>   5. R-390A RF DECK COAX CABLES IMPEDANCE (Jacques Fortin)
>>   6. Re: R-390A RF DECK COAX CABLES IMPEDANCE (Charles Steinmetz)
>>   7. Re: latest version "Pearls" (wli)
>>
>>
>>----------------------------------------------------------------------
>>
>>Message: 1
>>Date: Thu, 20 Oct 2016 03:53:45 +0000 (UTC)
>>From: Larry H <dinlarh at att.net>
>>To: "r-390 at mailman.qth.net" <r-390 at mailman.qth.net>
>>Subject: [R-390] R-390A VFO/PTO Quality
>>Message-ID: <655480848.82372.1476935625249 at mail.yahoo.com>
>>Content-Type: text/plain; charset=UTF-8
>>
>>Stan,  Take a look at the Pearls here:
>>
>>
>>http://www.r-390a.net/Pearls/PTO.pdf
>>
>>Regards, Larry
>>
>>
>>------------------------------
>>
>>Message: 2
>>Date: Thu, 20 Oct 2016 05:22:07 +0000 (UTC)
>>From: Perry Sandeen <sandeenpa at yahoo.com>
>>To: "r-390 at mailman.qth.net" <r-390 at mailman.qth.net>
>>Subject: [R-390] Receiver dust covers
>>Message-ID: <1529506914.149173.1476940927332 at mail.yahoo.com>
>>Content-Type: text/plain; charset=UTF-8
>>
>>List,
>>I did notice less noise on my R388 with the top cover on.
>>All the R388's I have are missing the bottom cover as well as 
>>almost all I've seen on Ebay. ?
>>I don't know how much difference it makes with it missing but I 
>>suspect it may be substantial as the sectioned modules have many 
>>screw holes for fastening one down.
>>Does anybody have experience do a shield-no shield test.
>>Regards,
>>Perrier
>>
>>------------------------------
>>
>>Message: 3
>>Date: Thu, 20 Oct 2016 09:28:05 -0400
>>From: Al Parker <anchor at ec.rr.com>
>>To: Perry Sandeen <sandeenpa at yahoo.com>, "r-390 at mailman.qth.net"
>><r-390 at mailman.qth.net>
>>Subject: Re: [R-390] Receiver dust covers
>>Message-ID: <67c68dbd-2319-7878-be40-1876c1945e5a at ec.rr.com>
>>Content-Type: text/plain; charset=utf-8; format=flowed
>>
>>Hi Perrier,
>>I've had and/or worked on 6 or 8 R-388's, many (maybe most) did have
>>the bottom cover, few had the top.  IIRC, somewhere in the manual it
>>says to do the alignment with the bottom cover on.  I remember 
>>aligning
>>one w/o the cover, then realized the mistake and did it 
>>right.  Didn't
>>compare performance before/after, but the re-alignment did 
>>require changes.
>>I hope you and your wife are doing well out there on the left coast.
>>73 (to a new ham, congrats),
>>
>>Al, W8UT
>>www.boatanchors.org
>>www.hammarlund.info
>>
>>"There is nothing -- absolutely nothing -- half so much
>>worth doing as simply messing about in boats"
>>Ratty, to Mole
>>
>>On 10/20/2016 1:22 AM, Perry Sandeen via R-390 wrote:
>>>List,
>>>I did notice less noise on my R388 with the top cover on.
>>>All the R388's I have are missing the bottom cover as well as 
>>>almost all I've seen on Ebay.
>>>I don't know how much difference it makes with it missing but I 
>>>suspect it may be substantial as the sectioned modules have many 
>>>screw holes for fastening one down.
>>>Does anybody have experience do a shield-no shield test.
>>>Regards,
>>>Perrier
>>>_________________________________________________
>>
>>
>>------------------------------
>>
>>Message: 4
>>Date: Mon, 24 Oct 2016 03:32:15 +0000 (UTC)
>>From: kg2bz at comcast.net
>>To: r-390 at mailman.qth.net
>>Cc: r-390 at mailman.qth.net
>>Subject: Re: [R-390] bfo hum and s meter not on zero
>>Message-ID:
>><1071890100.32651840.1477279935544.JavaMail.zimbra at comcast.net>
>>Content-Type: text/plain; charset=utf-8
>>
>>
>>
>>folks.  I notice a sight hum on cw and ssb with the bfo on. I 
>>also noticed my s meter no longer at zero but maybe around 1/3rd 
>>scale .  this occurred at the same time after I left on my 
>>receiver for several weeks. since both issues are in the IF deck 
>>I'm guessing it could be a cap or the neutralizing bfo cap c525 
>>adjustment?  thanks
>>Jeff KG2BZ
>>
>>
>>------------------------------
>>
>>Message: 5
>>Date: Mon, 24 Oct 2016 15:20:32 -0400
>>From: "Jacques Fortin" <jacques.f at videotron.ca>
>>To: <r-390 at mailman.qth.net>
>>Subject: [R-390] R-390A RF DECK COAX CABLES IMPEDANCE
>>Message-ID: <[email protected]>
>>Content-Type: text/plain; charset="US-ASCII"
>>
>>Hi to all,
>>
>>Does anybody already worked out the impedance of the coaxial cables
>>connecting to the RF DECK in a R-390A ?
>>They look very much like 75 ohms Teflon to me... RG-179/U ?
>>Just want to be sure.
>>
>>73, Jacques, VE2JFE
>>
>>
>>
>>------------------------------
>>
>>Message: 6
>>Date: Mon, 24 Oct 2016 19:01:11 -0400
>>From: Charles Steinmetz <csteinmetz at yandex.com>
>>To: r-390 at mailman.qth.net
>>Subject: Re: [R-390] R-390A RF DECK COAX CABLES IMPEDANCE
>>Message-ID: <580E92B7.6070909 at yandex.com>
>>Content-Type: text/plain; charset=utf-8; format=flowed
>>
>>Jacques wrote:
>>
>>>Does anybody already worked out the impedance of the coaxial cables
>>>connecting to the RF DECK in a R-390A ?
>>>They look very much like 75 ohms Teflon to me... RG-179/U ?
>>
>>Or 50 ohm RG-316.
>>
>>Why do you want to know?  All of the coax runs in the 390A are 
>>too short
>>to support wave propagation modes at the frequencies they are 
>>handling,
>>so they are really operating as simple unbalanced shielded 
>>cables, not
>>as transmission lines.  Note that the source and load impedances 
>>of the
>>connected circuits are not matched to the coax's characterstic 
>>impedance.
>>
>>Any cable that fits the connectors will work fine.  If you are 
>>looking
>>to optimize, choose the cable with the most effective shield.
>>
>>Best regards,
>>
>>Charles
>>
>>
>>
>>
>>------------------------------
>>
>>Message: 7
>>Date: Mon, 24 Oct 2016 23:10:11 +0000 (UTC)
>>From: wli <wli98122 at yahoo.com>
>>To: <r-390 at mailman.qth.net>
>>Subject: Re: [R-390] latest version "Pearls"
>>Message-ID: <1400510087.15983.1477350611263 at mail.yahoo.com>
>>Content-Type: text/plain; charset=UTF-8
>>
>>The fall issue is up thanks to Al
>>
>>W. Li
>>
>>
>>------------------------------
>>
>>Subject: Digest Footer
>>
>>_______________________________________________
>>R-390 mailing list
>>R-390 at mailman.qth.net
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>>
>>------------------------------
>>
>>End of R-390 Digest, Vol 150, Issue 26
>>**************************************
>>
>>
>>-----
>>No virus found in this message.
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>>Version: 2016.0.7859 / Virus Database: 4664/13267 - Release Date: 
>>10/24/16
>
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