[AMRadio] 75TH vs. 75TL (was Class C stuff)

[Brett Gazdzinski]

Bill,
This was a long time ago.

I was doing tests on frequency response.
Putting the signal generator into the audio chain and sweeping
it while watching the mod monitor.
When I got down to about 30 Hz POW!

It was no big deal, I paid $100.00 for the transmitter
including some other stuff along with it.

Mod transformers used to be under tables at fests for
$10.00.
That is what I paid for the thordarson I used to replace
the Collins transformer.

Sure was fun to learn by blowing things up back then.



Different story now....

I also traded a very clean 75a4 with 3 filters, and a 
very clean kws1 for a rack cabinet and rf parts...

Remember when all the tube stuff was worthless?

The new electric radio has info on the mod iron
protection circuit.
I use negative cycle loading on all the big stuff ...now...

I don't do low frequency at full power tests now...

Brett
N2DTS


> 
> >After I blew up the mod transformer,
> 
> Ouch, like the passing of species, another one gone. 
> 
> There are solid state methods to protect modulation 
> transformers, as well
> as operating techniques that will greatly reduce the risk of 
> this sort of
> tragedy ocurring. It's been several years so I'll have to 
> collect my notes
> on this topic. But beyond the obvious one of using 'tune' 
> mode to be sure
> you are not transmitting into an open antenna load, I'll leave it to
> others to add some detail here. Kinda mixed up with the 
> 'ultra-modulation'
> diode treatment, but diode strings are involved with 
> protecting mod iron
> as I recall.
> 
> Bill
> -- 
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