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Author Topic: Pride DX300 Self Oscillation Problem  (Read 2157 times)
N8FP
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Posts: 7




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« on: June 21, 2004, 10:07:04 AM »

I know that most hams dont like this amplifier because it lends itself to use on the CB Band. but it is a nice amplifier and is usable on other bands. Currently I have one of these that I am trying to repair and would appreciate any information given.
Problem that I am having is when the amplifier is keyed and tunned the amplifier will stay keyed and go into self oscillation. When this happens I am seeing DC output on the PEP meter but no AC output on the RMS meter (Bird). I have to either shut the amp off or detune the tank circuit to get the amp to stop oscillating.
Also after the amp has gone into self oscillation the operate and PowerOn LEDS are burned out.

The Voltages on the Plate, Filament,Control Grid and Screen Grid all check out O.K.
Is there anyone out there that could shed some light on this problem...??
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W8JI
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Posts: 9748


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« Reply #1 on: June 29, 2004, 07:05:27 AM »

You won't like this answer if you think the Pride is a "good amplifier".

The Pride is a poorly designed amplifier. It needs better regulation on the screen. It needs neutralization added or a better design in the grid swamping. The component values are off. The RF bypassing inside the amp isn't good.

I suppose you could strip it back and rebuild it correctly. Of course it would still be a bit dirty on SSB unless you added negative feedback. 250's aren't real clean tubes without special consideration to screen regulation and some negative feedback.

The problem isn't necessarily the fact it is a CB amp, the problem is virtually every CB amp...even the best of them...are not "designed" to do anything but make a power meter move.

If you get the Pride stable without correcting regulation and RF feedback issues, it still will be dirty.

73 Tom  
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