Many thanks to all who contacted me off-list. As most messages referred to the same issue, I thought I'd try and explain better why I think auto-notch on CW can be a useful QRM fighting tool.
The obvious reason for not having auto-notch on CW is either that it notches out the signal you are trying to listen to, or that it cannot differentiate between multiple wanted and unwanted signals. The secret is not to put too much thought or intelligence into it. The auto-notch should simply go for the strongest signal in the pass band; if it can also go for the second strongest, or equally strong, so much the better, but it doesn't matter if it can't, it will still have cut the QRM by at least 50%. The real situation in a DX pile-up is wanted DX signal is almost never the strongest signal (if it is - work it & move on - no problem!). It's the errant callers & tuner uppers (accidental or otherwise) and up up up police that cause the problem. An auto-notch that can take these out, even one at a time, is a great help & the stronger the signal, the easier it is for the auto-notch to hit & track it. And, by definition, it hits the biggest problem first. It needs a simple tap on, tap off access, as it needs to be disabled quickly if the frequency becomes clear. The Jupiter auto-notch is effective in not being very effective as it doesn't work on weak signals (good!) & just sits on the biggest signal it finds in the pass band (also good). Of course, if the interfering signal is exactly co-frequency, it'll kill the DX too, but this rarely happens as the human ear is very good at separating even a few 10s of Hz. If the frequency is completely jammed, it won't help either. I strongly believe the best filters & decoders are between our ears; an auto-notch that cuts down the biggest signal whilst letting the brain concentrate on the weaker DX underneath can be the difference between a QSO & a bust call. Worked VP6DX this week for an all-time new one, and K3 to K3! When the Eu. idiot brigade started up on 40M, I instinctively tried to engage the auto-notch & was surprised to find it not there. Am I the only person transitioning from a Ten-Tec radio to miss it? 73 Ian G4FSU _______________________________________________ Elecraft mailing list Post to: Elecraft@mailman.qth.net You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com
