[AMRadio] Ranger Audio... the numbers

Larry Taft ltaft at charter.net
Fri Nov 17 13:32:00 EST 2006

Try again, only this time wait to push "send".

Unfortunately an ohmmeter test on the leads of a xfmr will not show a 
turn to turn short in the same winding.  The real way to test is send 
AC, ie audio, into the iron at a modest power level and look at the 
waveform coming out.  Distorted waveform is the result of the shorted 
turn.  In power xfmrs the short  causes gross overheating and depending 
on the size of the xfmr some spectacular fireworks.

6L6 or 1614:  For all practical purposes they are the same at the 
voltages and power levels in the Ranger.  The 6L6 long term might be a 
bit stressed and not give as long a life.

73, Larry  K2LT

Jack Schmidling wrote:
> Gary Schafer wrote:
>> It's beginning to sound like a partially shorted mod transformer.
> I checked the resistances of the transformer earlier in the game and 
> they are nominal.
>  >With 20 volts signal on the grids of the mod tubes I would think 
> that >you should see at least 200 volts on the plates??
> I have no idea but if mine is off by a factor of 4, would it work at all?
>> Could be bad 6L6's.
> Or back to a reason for using 1614's perhaps?
>> Can you easily get high modulator plate current with audio applied? 
>> Will the
>> mod plate meter peg or nearly so if you hit it hard?
> Yes.
>> If it will that is an
>> indication that the tubes are good and the transformer may be shorted.
> Except that the transformer appears to be ok.
> To refresh..  we are talking about a max of about 75% modulation on 
> peaks but no problem over modulating at the base line.
> js

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