[R-390] R-390 (non-A) - Low RF Gain or bad Antenna relay?

Thu Nov 7 17:48:33 EST 2024

Ooops...I pressed send before I was finished typing...I had to adjust the 
height of the tuning shaft and then adjust again so the outer case of the 
PTO was parallel to the chassis where it is mounted...I have an OLD small 
spirit level I use for that and for checking turntables inter alia...

73...Jordan...

----- Original Message ----- 
From: "Jordan Arndt" <Outposter30 at shaw.ca>
To: "Jacques Fortin" <jacques.f at videotron.ca>; "Collins R-390 HF Receiver 
List" <r-390 at mailman.qth.net>
Sent: Thursday, November 07, 2024 3:39 PM
Subject: Re: [R-390] R-390 (non-A) - Low RF Gain or bad Antenna relay?

> Jacques...PTO #1 of 2 is put to good use... I have to tweak the 10 turn 
> coverage at the -000 end of tuning...The rest is very very linear...!
>
> The Collins PTOs don't fit quite the same as the Cosmos PTO I had 
> installed, and I had to slightly correct the height of the tuning shaft 
> and the adjust to
>
> 73...Jordan...
>
> ----- Original Message ----- 
> From: "Jacques Fortin" <jacques.f at videotron.ca>
> To: <k1jos at att.net>; <r-390 at mailman.qth.net>
> Sent: Thursday, November 07, 2024 2:55 PM
> Subject: Re: [R-390] R-390 (non-A) - Low RF Gain or bad Antenna relay?
>
>
>> R544 is just a Allen Bradley 470K, 10% ½W resistor.
>> The only Part List I know is in the first R-390/URR manual that you can 
>> download here:
>> https://www.royalsignals.org.uk/radio-rx-R390/2460.pdf
>>
>>
>> 73, Jacques, VE2JFE in Montreal
>>
>> -----Message d'origine-----
>> De : r-390-bounces at mailman.qth.net <r-390-bounces at mailman.qth.net> De la 
>> part de k1jos at att.net
>> Envoyé : 7 novembre 2024 16:11
>> À : 'Jacques Fortin' <jacques.f at videotron.ca>; r-390 at mailman.qth.net
>> Objet : Re: [R-390] R-390 (non-A) - Low RF Gain or bad Antenna relay?
>>
>> Fortunately, R544 is not under V510 where all the Amphenol Jack harness 
>> wires but seems to be in the compartment just above.  Doesn’t look like 
>> typical 2W CC but looks like much older style.  Will lift one end tonight 
>> after dinner and see.  Where can I find the parts list with component 
>> specifications.  I searched the TM 11-5820-357-35 manual.. Are they 
>> submanuals also?
>>
>> Jerry
>>
>> -----Original Message-----
>> From: r-390-bounces at mailman.qth.net <r-390-bounces at mailman.qth.net> On 
>> Behalf Of Jacques Fortin
>> Sent: Thursday, November 7, 2024 3:13 PM
>> To: r-390 at mailman.qth.net
>> Subject: Re: [R-390] R-390 (non-A) - Low RF Gain or bad Antenna relay?
>>
>> Jerry, because R544 is still open... !
>> Is your +B checks at +180V ?
>> With the R544 in place (and good in value) you should measure about +40V 
>> on the cathodes, yes !
>> Do not ask why those hi-value resistors fail.
>> I have seen this many times, but nobody can tell why.
>>
>> 73, Jacques, VE2JFE in Montreal
>>
>> -----Message d'origine-----
>> De : r-390-bounces at mailman.qth.net <r-390-bounces at mailman.qth.net> De la 
>> part de k1jos at att.net Envoyé : 7 novembre 2024 14:30 À : 
>> r-390 at mailman.qth.net Objet : Re: [R-390] R-390 (non-A) - Low RF Gain or 
>> bad Antenna relay?
>>
>> Before I replace R544, I wonder what caused it to fail.  Checking 
>> voltages per manual, with Limiter at maximum 10, there should be 0 vdc at 
>> the plate (pin 6) or grid (7) or cathode (8) which I confirmed.  However, 
>> with Limiter switched off there should only be 40vdc at the plate, grid 
>> and cathode and I find +155vdc.   Does this make any sense?
>>
>> Jerry
>>
>>
>>
>> -----Original Message-----
>> From: r-390-bounces at mailman.qth.net <r-390-bounces at mailman.qth.net> On 
>> Behalf Of k1jos at att.net
>> Sent: Thursday, November 7, 2024 2:08 PM
>> To: r-390 at mailman.qth.net
>> Subject: Re: [R-390] R-390 (non-A) - Low RF Gain or bad Antenna relay?
>>
>> I unplugged P117 from J517.  All connections from P117-9 and P119-10 to 
>> Limiter switch are intact.  There is no continuity from V507B-8 (cathode) 
>> to J517-9.  I checked directly at the tube sockets; V507B cathode and 
>> V510 cathode are continuous as per schematic so that rules out issues at 
>> the tube sockets.  It looks like it can only be R544... so now to remove 
>> the IF module.
>>
>> More to follow............
>>
>> Jerry
>>
>> -----Original Message-----
>> From: Jacques Fortin <jacques.f at videotron.ca>
>> Sent: Thursday, November 7, 2024 12:10 PM
>> To: k1jos at att.net; 'Barry Scott' <72volkswagon at gmail.com>
>> Cc: r-390 at mailman.qth.net
>> Subject: RE: [R-390] R-390 (non-A) - Low RF Gain or bad Antenna relay?
>>
>> Jerry, looks like R544 is open, or just not there anymore !
>>
>> 73, Jacques, VE2JFE in Montreal
>>
>> -----Message d'origine-----
>> De : r-390-bounces at mailman.qth.net <r-390-bounces at mailman.qth.net> De la 
>> part de k1jos at att.net Envoyé : 7 novembre 2024 10:46 À : 'Barry Scott' 
>> <72volkswagon at gmail.com> Cc : r-390 at mailman.qth.net Objet : Re: [R-390] 
>> R-390 (non-A) - Low RF Gain or bad Antenna relay?
>>
>> Hi Barry,
>>
>> Could you do me a favor and also check resistance on V507B (Neg Peak 
>> Limiter) pin 8 cathode -- It should read 500k (Limiter knob at full CW) 
>> and 450k with Limiter switch OFF - I read an open circuit or resistance > 
>> 10Meg.  The cathode of V507B is tied to the cathode of V510  (pin 3) 
>> which also reads open on my DMM.
>>
>> Thanks in advance
>> Jerry
>>
>> -----Original Message-----
>> From: Barry Scott <72volkswagon at gmail.com>
>> Sent: Wednesday, November 6, 2024 10:52 PM
>> To: k1jos at att.net
>> Cc: r-390 at mailman.qth.net
>> Subject: Re: [R-390] R-390 (non-A) - Low RF Gain or bad Antenna relay?
>>
>> I just checked resistance from V506 Pin 7 to ground in my R-390/URR and 
>> it checks a few ohms over 820 ohms.
>>
>> Thanks,
>> Barry - N4BUQ
>>
>> On Wed, Nov 6, 2024 at 8:38 PM Barry Scott <72volkswagon at gmail.com> 
>> wrote:
>>>
>>> That resistance measurement seems quite odd.  R536 is supposed to be
>>> 820 ohms.  Unless C523 is bad, I don't see how there should be
>>> anything much less than 820 ohms at pin 7 of V506 yet the resistance
>>> diagram shows 700 ohms.  99 ohms seems very wrong.
>>>
>>> Thanks,
>>> Barry - N4BUQ
>>>
>>> On Wed, Nov 6, 2024 at 8:12 PM <k1jos at att.net> wrote:
>>> >
>>> > Update....
>>> >
>>> > I checked voltages and resistances per TM  11-5820-357-35 (09 March 
>>> > 1962) for the IF amps V501 - V506.  I don’t know if my R-390 had any 
>>> > mods, its SN 1256, but all the results were very close to the listed 
>>> > values except for V506, 6th IF amp.  The cathode should read  700 ohms 
>>> > to ground and 8.2vdc and I find 99 ohms and 2.3vdc.   The schematic 
>>> > shows the cathode bias resistor of 800 ohms and a 15ohm pot for 
>>> > carrier meter adjustment.  There is a decoupling cap 0.1uF off the 
>>> > cathode that if leaky could bring the resistance down to my reading. 
>>> > But would this be enough to drop my gain so dramatically?
>>> >
>>> > Jerry
>>> >
>>> >
>>> > ______________________________________________________________
>>> > 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
>>
>> ______________________________________________________________
>> 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
>>
>> ______________________________________________________________
>> 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
>>
>> ______________________________________________________________
>> 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
>
> ______________________________________________________________
> 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 