Re: Low Power - Final Amplifier on through - hole kit
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Yes, the bias of the IRF 510 is set to 50mA per the instructions that came with the kit. I will take a look at the gate's AC & DC voltages tonight.
Maybe it is a distortion issue of some sort in the exciter.
I am an EE student. After classes begin on Monday I will have access to my school's lab. I will then have a very fast scope, signal generator, spectrum analyzer, and even a network analyzer.
Jerry, my scope is an old 20MHz analog thing probably right out of the 80s. It was free so I don't complain. :) Since it is analog with a scanning beam, I am able to see the amplitude of the waveform, but the individual periods are quite close together and it is hard to see the shape of the waveform.?
Thanks guys!
~Mark, KC9DZT
On Fri, Jan 20, 2017 at 9:17 AM, Jerry Gaffke via Groups.Io <jgaffke@...> wrote: 2v pk-pk sounds about right to me, though I don't really know. Output pk-pk voltage should be about the same with or without the filter and that seems to be pretty much the case, you have trouble elsewhere. I assume you have the bias voltage into the gate of that IRF510 set correctly, what is your current draw when the transmitter is quiet? I'd be really curious what the DC and AC voltages are on the IRF510 gate.
With the output filter and the filter at the IRF510 gate both removed, this amp should be very broadband. Maybe create a source of a couple MHz at 2v pk-pk and feed that into the amp, that might let you better see what's going on with a slow scope. Might be able to use your VFO, adding a bunch of caps to lower the frequency. Weird that you can tell the amplitude "is pushing 2v pk-pk" if the scope is otherwise too slow to display it, a simple diode RF probe might be a more suitable instrument to measure RF voltages. ? ?
Hopefully somebody out there more familiar with Sunil's design can give you some better pointers.
Jerry, KE7ER
-- Mark Baldridge 608.561.3853
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