[R-390] Re: Ballast Tubes/Motor Start Capacitor

[Bob Camp]

Hi

I actually tried method 4 below. I think I was 15 at the time. As I 
recall the filament in the tube just sat there dark and the capacitor 
got real hot just before it took out the line fuse. Not a recommended 
way to run a 6L6GT directly off of line voltage using a non-polar 
electrolytic.

	Take Care!
	
		Bob Camp
		KB8TQ


On Jul 4, 2004, at 5:45 PM, Michael Murphy wrote:

> Method 4: Actually, a non-polarized capacitor would run cooler to drop 
> a few
> Watts. I come up with 100 uF - 120 uF. Somebody check my math. This mod
> should confuse the ballastless b*^*$%ds who have to inherit our 
> R390A's.
>
> Method 5: The resistance linecord idea. For extra credit calculate how 
> many
> inches are required for 50 Ohms. Wrap this solenoid style around the
> existing tube to form a common mode choke to reduce interference from 
> BPL
> which I figure, must be getting into the VFO fillaments.
>
> Happy 4th all!
>
> Mike WB2UID
>
> ----- Original Message -----
> From: "Tom Norris" <r390a at bellsouth.net>
> To: <R-390 at mailman.qth.net>
> Sent: Sunday, July 04, 2004 3:51 PM
> Subject: [R-390] Re: Ballast Tubes/transmitting receivers/Dogs and Cats
> sleeping together...
>
>
>> I suppose the common 12BY7 ballast replacement could by used
>> in a simple MOPA circuit, or maybe crystal controlled like a Tuna
>> Tin transmitter...
>>
>> Hmmm
>>
>>
>>
>>> Has anybody ever investigated the possibility of switching the 3TF7 
>>> out
> with
>>> a triode-pentode that could do double duty as a ballast and a
> transmitter?
>>> Seems like an R-390A/URT Transceiver could be a possiblilty. Heck, 
>>> you
>>> already have a T/R relay built in, all the power supplies you need, 
>>> and
>>> crystal oscillators. Probably too much to ask for plate modulation, 
>>> but
> for
>>> CW it might be a great rig, if a bit on the overdesigned side on the
>>> receiver part.
>>> Jerry W5KP
>>>
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