[R-390] Cooking Kielbasa 2 of 2

[Flowertime01 at wmconnect.com]

Fellows,

I used a 50 ohm 10 watt resistor for the RT512 3TF7 ballast tube in the 
R390. I measured a 13.6 voltage drop across the ballast and the resistor. 13.6 
volts at .3 amps is 4.08 watts of heat from the resistor. I measured 12.6 
volts across the two 5749's in series with the ballast tube and the 50 ohm 
resistor. I though the 50 ohms would be high expecting 12.6 volts at .3 amps to 
yield 42 ohms. I found no measurable difference in receiver performance 
with either device in the VFO BFO circuits.

I had potted the resistor in epoxy and PVC to make a mechanical fit of the 
resistor into the tube socket. I find the 4.08 watts a bit warm but not more 
so than the glass ballast tube. 4 watts of hot glass is just not the same 
as 4 watts of hot plastic. I can except finger burning glass tubes but not 
finger burning plastic. The replacement device works as expected, It just does 
not feel right.

Roger AI4NI


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