[Top] [All Lists]

[CQ-Contest] 87A question

Subject: [CQ-Contest] 87A question
From: dick.green@valley.net (Dick Green)
Date: Mon Jan 22 01:01:58 2001
 > My question is: did that dit ever get transmitted
 > .. even at low power? If I didn't give it a dit, how much of my first
 > character would be muted because the amp doesn't yet know its on the wrong
 > band? It must take a while to actually measure the frequency and
 > kick in the
 > QRP bypass.  I know its quick, but how quick?

Interesting question. I've seen numerous claims by Alpha that the dit will
be transmitted at low power -- i.e., the amp is bypassed during band
switching. My guess is that it takes less than a millisecond to measure the
frequency and bias the PIN diodes to bypass the amplifier, and probably far
less than that to switch the amp back in after the steppers retune.

I don't know how they do the RF sampling, but even if they had to wait an
entire cycle at 1.8MHz to determine the frequency, that would still be less
than a millisecond. My guess is that the detection takes place faster than
that (and certainly faster at higher frequencies.) So, my conclusion is that
no audible portion of the dit is lost.

You should still use the dit, though -- sometimes it takes those stepper
motors a couple of seconds to QSY, during which time everything you send
goes out at low power. Not good during a high-speed CW run.

73, Dick WC1M

CQ-Contest on WWW:        http://lists.contesting.com/_cq-contest/
Administrative requests:  cq-contest-REQUEST@contesting.com

<Prev in Thread] Current Thread [Next in Thread>