[AMRadio] Testing a modulator

w6ref at comcast.net w6ref at comcast.net
Thu Feb 28 14:26:29 EST 2008

Hello Dick,

Your method seems fine to me...it's what I do. A high wattage resistance across the secondary close in value to the load impedance will work. Use your signal generator and a scope to check waveform purity over the desired frequency range, but be careful with your probe. The secondary voltage will be several hundred volts. Also, like you said, short tests are mandatory.

Good luck,


 -------------- Original message ----------------------
From: "RICHARD GEORGE" <k6kwq at msn.com>
> How does one test a modulator. I will soon have a modulator capable of 
> around 100 watts of audio. I know that I do not want to run the secondary of 
> the transformer unloaded. Would it be OK to make dummy load out of a bunch 
> of parallel connected 3 watt resistors, say about 60 watts worth at the dc 
> resistance I will be looking at (3000 ohms).
> I know that this would only be good for short tests using my O scope and 
> audio gen. Any better ways.
> I ran a lot of VHF AM back in the day, but only at 5 - 10 watt levels.
> K6KWQ Dick
>  Amps by "MORE POWER" 

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