[AMPS] New to list.

[Steve Katz]

> Hello to all .
> 
> I joined to pose a questionand also to copy mail to see what is new.
> 
> I have a solid state push pull Broadbanded RF amp 
	[Steve Katz]  What amplifier is that, exactly?  If not commercially
made, then what's the circuit, intended frequency range, transistors used,
voltage applied?  How's it biased?
> that I have replaced
> the transistors but the unit is taking off at higher power levels. I
> placed a LPF on the input drive to the amp as I would see the 3 harmonic
> at 6 dB below the carrier!  THe filter cured that.  Looking at the
> signal from an HP analyzer
	[Steve Katz]  "From an HP analyzer?"  Do you mean "on an HP
analyzer?"  How are you decoupled to keep from overloading the analyzer?
What level signal are you actually looking at, e.g., the analyzer is seeing
+10dBm from a +50dBm signal, using a 20dB directional coupler and a 20dB pad
to knock down the signal...stuff like that.
>  , I see multiple harmonics spaced about every
> 2 Mhz below the carrier frequency into a 50 Ohm load. On lower power
	[Steve Katz]  Sounds like it's oscillating at 2 MHz and modulating
the applied signal.
> levels, the closest is 20 dB down , but at higher only 10dB On an
> antenna , It takes off and pulls horrendus currents and drags the supply
> voltage down to 9 or 10 volts if I plase it on an antenna with a tuner.
> 
> ?...Is it normally required to neutralize this amp when replacing the
> finals?  
	[Steve Katz]  What are the finals?  What is the circuit?
	-WB2WIK/6

> ?...What techniques are used to do this?
> ---
> Ron
> 
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