[R-390] SERIAL # 163

[Renée Deeter]

looks like what he has is a prototype Stewart Warner IF deck with the 
product detector.
Renée, K6FSB

RICHARD MC KINNEY wrote:
> I just found the product detector mod and it looks like that is what 
> has been done to this rig.  But my rig had a 6BA6 in the bfo slot and 
> the mod calls for a 6BE6.  So now I get a 6BE6 and go from there.  
> Thank you for the info.  73 Rich WB4VFN
>
> ----- 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 7:27 PM
> Subject: Re: [R-390] SERIAL # 163
>
>
>> 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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