[MRCA] T-195B and volts

[B. Smith]

      The specs for the T-195 call for 22 to 30 volts. Period. My T-195  
servo system works very well within that range. I seriously doubt that 
a  radio manufactured for  "Field Use" would require a precise battery 
voltage.

       I've attached photos of the T-195 meter showing meter indications 
for 22 and 26 volts. Recheck voltage at the input of the set by removing 
the connector cover -  insert the connector- and measure at the input to 
the set.   Remember you will have voltage drop due to cable resistance 
so don't be concerned if the voltage measured at the set is a couple of 
volts lower than indicated by your power supply.  I've attached specs 
and 2 photos of meter indications. BTW I don't recommend running the set 
for extended periods at 22 volts as the filament voltage for the finals 
would be pretty low. I would  trouble shoot the system. BTW I install a 
switch to turn off the 400 cycle supply after tuning to end that servo 
dithering and this will save the servos.
Z








On 9/26/2015 10:40 AM, DSP3 wrote:
> The high B+ is not critical to the radio, nor especially to the servo 
> system.  That said, with the two systems I work with, the input 
> voltage is set at 28.7 volts.  If you take a very close look at the A 
> and B models, many of the nomenclature tag appears to say 29 volts!.. 
> something like that.....   On one of the ones I had, it was imperative 
> to run at least 28.6 volts for the autotune to actually settle.  I am 
> unsure of the total reason but the book clearly states that the two 
> pairs of matched diodes in the servo discriminators should be changes 
> every 60 hours of operation.  That seems a bit short but that's what 
> it says.  The original diodes are germanium and perhaps that's a clue 
> to the low longevity in that circuit. Also, the sampling choppers can 
> go bad\.  I still have a few of them I bought.  They go in the T-195 
> and, I understand, in the ARC-38 (sic) and others.
>
>
> Jeep K3HVG
>
>
>
> On 9/26/2015 8:22 AM, Robert Newberry wrote:
>>
>> On the AM net this morning, I was given the advice of how important 
>> 28 volts DC input is with regards to autotune.
>>
>> Currently I am using a external HV supply that will not quite make 
>> 1000 volts. We are using current limiting because if you use the 
>> solid state one the current will destroy the supply. I am still using 
>> DC input with a variable supply to run the low voltage section which 
>> has tested out OK.
>>
>> Does anyone know if I can't get exactly 1000 volts will that affect 
>> autotune?
>>
>> I suppose at a minimum I can use the external supply until I find 
>> whatever is drawing so much current.
>>
>> Thank you
>>
>> N1XBM
>> Apparare Scientor
>> Paratus Communicare
>> Allstar Node # 27086, 41540, 41812, 42086
>>
>
>
>
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