[MRCA] T-195B and volts

[Grasshopper]

on my t-195b, i have found the with less than 28v, the low voltage/400 hz system will not engage.  

Steve, kd3ht

Sent from my iPhone

> On Sep 26, 2015, at 12:58 PM, B. Smith <smithab11 at comcast.net> wrote:
> 
>      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
> 
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> 
> 
> <gbjajjfg.jpg>
> 
> 
>> 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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