[MRCA] T-195 Power Supply Options

[Mike Murray]

--- On Sun, 11/1/09, D. Platt <jeepp at comcast.net> wrote:
> Having some limited experience with the issue(s) and with
> all three 
> variants (that is, all dynamotor, HV solid-state/LV
> dynamotor, and all 
> solid-state), that I had, might I offer my anecdotal
> information.   I 
> measured the in-rush current of my all-dynamotor unit at 95
> Amps (peak) 
> for approx. 2.8 seconds.  The rise-decay time was
> measured for when the 
> current dropped back below 50 amps.  The method used
> was via a 466 
> storage scope and a 100A shunt.  I also found that the
> in-rush was less 
> that 50A for the one with the solid-state (only) power
> supply.  The all 
> solid-state unit ran an even 36 amps with no appreciable
> in-rush.  My 
> impetus was to see what was necessary to run the units with
> a PP-4743A 
> (GRC-106) power supply.  The all-dynamotor unit would
> _always_ pop the 
> PP-4763A breaker.   Until modified, I used a
> commercial, 60 amp, 
> ferro-resonant supply that would sag to about 18v during
> the inrush 
> period and build as the in-rush decayed.  This supply
> was very 
> tolerant*, obviously, and was used successfully with a
> PE-73C dynamotor 
> with the BC-375.  My other setup had a Navy 40 amp
> supply and two sealed 
> lead-acid batteries.  The system worked well butt he
> issue with them was 
> that the T-195( ) likes to have something above 28v and
> that caused the 
> batteries to be charged at higher than acceptable value
> (Rock and hard 
> place...!).  That setup was relegated to the BC-375
> for a while as 24-26 
> volts was OK.  Just before I divested the GRC-19's,
> here, I did build up 
> an in-rush box consisting of a 1000w, 0.2 ohm wire-wound
> resistor assy 
> and a 100A contactor.  Although theoretically it
> should (how much?) have 
> worked, I never got to finish the PTT "keying"
> circuitry.  Wish I 
> had........  Finally, sage individuals have told me on
> various occasions 
> that the condition of a dynamotor will effect the in-rush
> current 
> (BGO?).  Further, that new bearings and lubrication
> may have noticeable 
> effect.  Any help?
> 
> Regards   Jeep/K3HVG

Yes, thank you, Jeep. This is *immense* help.
We were wondering about the rise-decay time measurements, and I'm sure yours are accurate.
Will report back.

TNX es 73
Mike
KW4HF


> 
> *  I've been told that the straight, single-breaker,
> straight PP-4763 is 
> more tolerant of surge currents, vice the "A" model with
> its dual, 
> high-sensitivity breakers and that if the breakers in the
> "A" model were 
> removed and replaced with SB fuses, they too will tolerate
> higher (sic) 
> surges.  The efficacy of this fix was never pursued,
> in my case, nor do 
> I believe it would solve the all-dynamotor in-rush issue