A side note to this topic for RF amplifiers, in general:
I have not heard of this "paper crunch" noise description, before this, but it's well known with VHF and up operation that one does want to remove bias during receive on many amplifiers due to "white" noise being generated. Perhaps this is not detected from HF amplifiers because sky noise is much higher and it is not heard.
I initially ran a 50w modified 900-MHz amplifier on 1296-eme and making a quick connection did not bother with switching the keying line which enabled/disabled bias. I was puzzled why my noise floor was 6-dB higher than normal (I monitor the noise floor in receive with a SDR-IQ set for maximum span (190-KHz)). Someone replied to my e-mail comment suggesting that bias might not be set to cutoff. That was the solution and once I connected up a TR line to key the amp for Tx (and unkey it in Rx) Rx noise was back to normal (sky noise at 1296-MHz is in the region of 10K vs 20,000K at 28 MHz).
This is probably not related to the "paper crunch". 73, Ed - KL7UW http://www.kl7uw.com "Kits made by KL7UW" Dubus Mag business: [email protected] ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[email protected] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to [email protected]
