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Tube amp gurus! Need advice on a little RF tube amp refurb.
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Engineering & Manufacturing > Electrical

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  • Posted: Tue, Oct 09, 2012
  • Time Left: Closed
  • Location: Anywhere
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  • Start: Immediately
  • Budget: Less than $500
  • Fixed Price Job
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I have a new question for you. I have attached the schematic of an amp I am trying to refurbish. It is old and seems to work fine. It has a receive preamp which I am speaking about... the amplifier is what we call "bilinear". It is designed to amplifier RF energy (1-4watt input) in the 25-30 mhz frequency range and output around 275 watts.

The part I am currently working on is the rf preamplifier circuit. It is toggled on and off by switch "REC" as per the attached schematic. I was hoping you would know what ideas for mods or improvement I can do the the stock rf preamp as this is a 30 year old design... i found 2n5089 might work so much better than 2n3904... can you please explain this little circuit for me? RY3 tunes the receive preamp?

Any ideas or mods you can think of would be appreciated! As you can see the tubes 8950 are rare and expensive now but managed to find NOS tubes for 100 dollars. Some people are converting 8950 to other tube types... are you f...

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