[MRCA] T-195 Auto-NoTune

[B. Smith]

I gave up on the dynamotor power supply for my T-195 years ago. Built up 
my "junk box" supply  in sections.  On the left is the HV and 400 cycle 
supply. On the right are the Bias and Screen supplies. I cheated a 
little bit on the Bias supply and used a small Lambda supply picked up 
at a ham fest. 28 Volts is supplied by the Operations Center  DC  buss 
and everything is metered including bias with the exception of the 400 
cycle line (I did not have any 400 cycle AC meters) The 400 cycle line 
does have a neon indicating light on the front panel . Building the 
supplies in sections allow for easier maintenance and gives your back a 
break.  Note that the HV supply is on small wheels.   :-)  Once the set 
is tuned to frequency  I turn OFF the 400 cycle supply to keep the 
servos from hunting  and sitting around making that little dithering 
noise.  4 wires to the T-195 with a 24 volt control relay installed in 
the HV section.   See attch photo.
Z




On 7/15/2015 6:46 AM, DSP3 wrote:
> Corollary to the current discussion, I've been thinking (dangerous 
> activity!) about building an external  KV DC supply for the T-195( ) 
> transmitters.  The original dynamotor requires about 68 amps of inrush 
> current.  The running current is maybe 35-40 amps, key down.  The HV 
> dynamotor is the killer for the PP-4763 and the 7333.  Also poor old 
> K2 takes beating in the straight T-195.  I figure one would need 4 
> wires for the interconnect; ground, "start", control, and B+.  The 
> T-195B (with the Victoreen solid-state supply) requires a straight 32 
> amps to start and run.  Now, the rotary unit that makes the 400 Hz 
> voltage would have to stay, of course as it produces multiple 
> voltages.  Some units are mobile, of course, but many are at home and 
> permanently ensconced.  A hidden power supply might be an idea and DC  
> current might be reduced to as low as maybe 20 amps, total?   Any 
> interest?
>
> Jeep - K3HVG
>
>
> On 7/15/2015 6:31 AM, DSP3 wrote:
>> Chris,
>>
>> But that I was the guru for the GRC-19, but that's not the case, of 
>> course.  An area of concern for the servo system are the matched sets 
>> of discriminator diodes.  The manual admonishes to change these 
>> diodes on a VERY regular basis, something like every 60 hours of 
>> use!. To even mention those specific components is a clue.  I think 
>> the requirement for a higher DC bus voltage is not a design issue but 
>> one where other components in the servo loop are deteriorating.  I'd, 
>> of course, check the tubes in the servo chain and then replace the 
>> diodes.  The a.c. chopper could also be going bad.  Its the same part 
>> as in the ARC-38.  They're available and not too expensive, either.  
>> The last time I found them, they were about $20 each.  I may still 
>> have one or two here and someone on the group will surely have some.
>>
>> Jeep - K3HVG
>>
>
>
>
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