[MRCA] T-195 Power Supply Options

[mac]

Mike,

First of all, which power supplies do you have in your T-195, i.e,  
mechanical dynamotors or the later solid state replacements.  If the  
latter your switcher may work OK without any capacity or other  
assist.  Many T-195s I've seen have one of each, usually solid state  
HV and mechanical for +250, -45 & 115V-400 cps. which still requires  
some surge capability but not as much as the 1000 volt unit.

DO NOT try to hang a bunch of caps across the output of your  
switcher.  Better way is to shunt  a couple of seriesed 12 volt car  
batteries across your supply through an isolating diode to prevent a  
reverse current flow back into your PS.  Adjust your PS voltage to  
give 2-3 amps charging current to the battery under no-load condx and  
connect the -195 across the battery terminals.  The diode should have  
a rating of 200 A or so, no problem these days.

You can  also use a pair of smaller power supplies to run the T-195.   
The load is split almost perfectly 50-50 at the primary power input  
connector, see your manual for the pin-out.

I built the supply that Ted uses.  It's simply an old garage Hot-Shot  
charger with the selenium rectifier replaced by a solid state bridge  
and something more than 100,000 mfd (I don't remember exactly) hanging  
across the output.  No regulation but not needed with the -195.  Have  
since duplicated this circuit in a nice cabinet with a variac, meters,  
etc. and use this for my GRC-19s.

Dennis D. W7QHO
Glendale, CA



On Oct 31, 2009, at 2:15 PM, Mike Murray wrote:

> OK, guys, second question:
>
> As some of you know, I recently acquired a AN/GRC-46 with  
> "everything except the shelter" (as Brown stated it) in VG condition.
> Ted and I took it for a test drive in Gilbert, and I have issues  
> with the T-195. The R-392 is excellent, though, so I am happy already.
>
> Vic-K0OUX here in town and I are weighing options for a power supply  
> to run the T-195 and begin our troubleshooting.
>
> We were wondering how others are running their T-195s and what  
> options we have.
>
> We have a 28V 100A power supply and 5 huge caps - 75VDC 60,000uF.  
> The PSU is switching, however, and we were hoping to limit the  
> surge. Possible? Anybody know the time constant of the surge?
>
> What else can I do?
>
> I know I need to replicate Ted's awesome supply!
>
> Thanks again guys!
> 73
> Mike
> KW4HF
> Chapel Hill, NC
>
>
>
>
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