[R-390] SERIAL # 163

[Renée Deeter]

Hi Rich-
I should have stated that mine does not have a relay in the circuit. the 
BFO was standard ( it now has a 7360).
I apologize in  raising your hopes and thinking that I had your circuit. 
I do not think that any units ever had a relay in the switching circuit, 
exception of one by someone that worked at the factory and it was a pet 
project etc...
So how much resistance in the cathode? it does add negative feedback and 
may be the problem causing the oscillator to shut down, it also may be 
shifting the bias enough to do the same.
Renée

RICHARD MC KINNEY wrote:
> Thanks for the quick responce.  Do you have a schematic for your model?
> The relay is good and switches out all audio output.  But the big 
> difference is in the BFO circuit.  In the print I have the cathode of 
> the bfo tube goes to the bfo coil.  In this rig the cathode goes a 
> resistor to ground.  If you could send me a print of that kind of BFO 
> it would sure help.  73 Rich
>
> ----- Original Message ----- From: "Renée Deeter" <k6fsb.1 at gmail.com>
> To: "RICHARD MC KINNEY" <pmcknney at bellsouth.net>; <r-390 at mailman.qth.net>
> Sent: Thursday, March 26, 2009 6:21 PM
> Subject: Re: [R-390] SERIAL # 163
>
>
>> Hi Rich
>> I have a 390A from a Collins 51 contract, sn 122  with all early
>> modules.  there were many mfgs of the rcvr....so who made it? also check
>> the rear for matching sn/mfg as the tags were/are interchangeable.
>> go for the simple things first......I understand loosing just BFO
>> output? or entire radio audio output?
>> if just BFO
>> 1 B+ voltage on the BFO tube ( tube extender is good here)`if not how
>> about dirty relay contacts..or are they actually switching?
>> 2. check all voltages the tube if 5749(6ba6) should be about the same no
>> matter the circuit....
>> 3. is the tube good? try a couple by substitution as it could have a
>> short internally
>> 4. visual for burned parts resistance and cap checks.......
>> unless it is a mod it probably worked in the past...if it is a mod then
>> the question becomes..did it ever work?
>> If all the audio.....hmmmm  short/open .... does the relay switch things
>> other than B+? ie audio...remember back to simple first....lets not tear
>> into it jsut to find the relay was ot switching and or making contact.
>> Renée, K6FSB
>>
>> RICHARD MC KINNEY wrote:
>>> DE WB4VFN Rich
>>>   I have a R390a Serial @ 163.  Problem is turning on the BFO looses 
>>> all output.  Rx is ok all bands with BFO off.  I have a manual for 
>>> thr R390a but I guess mine is an earlier model.  The BFO in mine is 
>>> nothing like the schematic.  Mine has a small relay that is switched 
>>> on by the BFO switch.  I don't think this is any kind of mod as it 
>>> looks factory wired. The BFO circuit is also very different then the 
>>> schematic I have.   The rig was given to me and I would love to see 
>>> it work again properly.  So far I've had to change the 17 mc crystal 
>>> and a few tubes to hear it work again.  Anyone have a schematic with 
>>> a relay in the BFO switch?  73 Rich
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>
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