[Milsurplus] National R-1230 countermeasures receiver

[Peter Gottlieb]

We are talking about using an ohmmeter to figure out the pin connections.

Still a couple of steps away from connecting any power.



On 12/1/2011 9:13 PM, J. Forster wrote:
> Peter,
>
> You have to be really careful with that approach. Quite a few radios do
> not ground the (-) side of B+, as an example.
>
> If you return B- to ground on an R.1155, you will upset the bias badly.
>
> On some radios, you will mess up the DC bias on the output tube and burn
> out the Output Transformer. Output transformers are no longer available in
> many cases.
>
> Best,
>
> -John
>
> =================
>
>
>> Ah, I see, not so easy in that unit.  The tube extenders will help, and
>> you can
>> also guess something from ohming out to the fuseholders as well.  The high
>> current ones will be filament connections.
>>
>>
>> On 12/1/2011 8:29 PM, HL wrote:
>>> Peter:
>>>
>>> Many thanks.  I have travelled down that road to some extent.  The power
>>> plug is an Amphenol 18-1 with ten pins, A through J.  "H" is probably
>>> ground. "A" and "B" are probably 115VAC. "F" and "G" are tied together
>>> and not used --unless as a bridge.  The other pins go through fuses to
>>> hidden areas in silver module boxes as seen in the photo I took of the
>>> bottom interior:
>>>
>>> http://online.sfsu.edu/~hl/R-1230FLR.html
>>>
>>> The receiver has 28 tubes and assorted lamps that receive ACV from four
>>> taps on the separate power transformer: 6.3V at 0.5A,
>>> 18V at 4.0A, 5VAC at 5.0A, and 7.3VAC at 30.0A. Note from my photo that
>>> the tube bottoms are hidden in these modules, so if I don't find the
>>> schematic,
>>> I will have to use Vector 9-pin and 7-pin tube extenders to trace the
>>> filament connections of each tube individually to determine how they are
>>> grouped.
>>>
>>> I enjoy this kind of mystery solving, but, alas, this receiver weighs 65
>>> pounds.
>>>
>>> Regards, Hal KK6HY
>>>
>>> On Dec 1, 2011, at 4:36 PM, Peter Gottlieb wrote:
>>>
>>>> You should be able to figure out several pretty easily.  Start with
>>>> ground, then use an ohmmeter to track back from a 6 volt tube to the
>>>> 6.3 VAC pins, same for a 5 volt tube.  Find a plate of some output tube
>>>> and that should lead you to B+ input (175 VDC?  or is there a separate
>>>> supply run by 115 VAC inside?).  Either way you will know, and
>>>> presumably there is some 115 VAC transformer in there from which you
>>>> can ohm out those input pins.  That kind of technique should get you
>>>> pretty far.
>>>>
>>>> On 12/1/2011 6:44 PM, HL wrote:
>>>>> Wanted: manual, schematics for National Radio Company’s 1963
>>>>> countermeasures receiver, Models R-1230 (aka: R-1125 or AN/FLR-11 or
>>>>> AN/FRA-54). (Manual ID: NAVSHIPS 94581) I think I can deal with its
>>>>> 65kHz IF output, and I can provide the needed power voltages, but am
>>>>> stymied without a schematic by the power connector with its ten
>>>>> unidentified pins (A through J) for 175VDC, 6.3VAC, 18VAC, 5VAC,
>>>>> 115VAC, etc. Would love to get this wonderfully built, complex beast
>>>>> operating! Any info will be appreciated. Holiday greetings, Hal KK6HY
>>>>> _
>>>
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