[ARC5] R-27/ARC-5 Hookup Question

[Mike Hanz]

Well, to a degree.  Remember that this is a *composite* voltage reading 
of the 1st and 2nd IF amp screens, and indirectly through a 200 ohm 
isolation resistor, the RF amp and mixer screens (using the AN/ARC-5 
example.)  So if all four tubes had low emission, it would in fact 
decrease the average screen (and plate) current, so the screen voltage 
indication would edge toward the higher end of the range.  That won't 
pinpoint a specific tube, however.  If one of the tubes had a gassy 
condition, it would bring the screen voltage down (perhaps not enough to 
take it below the low limit, however)...but then the radio would 
probably not be working very well. :-)

  - Mike

On 7/20/2013 9:12 AM, J. Forster wrote:
> OK.
>
> Next question, does the screen current of tubes give an indication the
> tubes are getting 'weak'- having low emission?
>
> I can see that it would change w/ gas.
>
> -John
>
> ==================
>
>
>
>> It's basically a go/no go indication, John.  There is a range of normal
>> readings, and if it's outside that range, then you have to use your
>> noggin and the Theory of Operation and Maintenance sections of the
>> manual to find out why. (cf. Paragraph 5-18 in the AN/ARC-5 manual for
>> the process.)
>>
>>    - Mike
>>
>> On 7/20/2013 8:18 AM, J. Forster wrote:
>>> Mike,
>>>
>>> Do any of the manuals on the receivers or test sets give any details
>>> about
>>> the use of screen voltage in testing or aligning the receivers, or is it
>>> just a go/no go indicator AFAYK?
>>>
>>> -John
>>>
>>> ============
>>>
>>>
>>>
>>>> On 7/19/2013 7:51 PM, Kenneth G. Gordon wrote:
>>>>> On 19 Jul 2013 at 14:46, J. Forster wrote:
>>>>>> Does anyone have an opinion why they bothered to bring the screen
>>>>>> saupply
>>>>>> out to a pin?
>>>>> In my opinion, it was used when testing the receiver to make sure
>>>>> those
>>>>> two black wire-
>>>>> wound resistors in the rear were OK.
>>>> Exactly right.  See the Command Set Test Equipment page at
>>>> http://aafradio.org/docs/Command_Set_Test.html and the SCR-274N test
>>>> set
>>>> page at http://aafradio.org/docs/ARC_Test_sets.html
>>>>
>>>>         73,
>>>>     - Mike
>>>>
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>
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