The bias point of the PA transistors can vary as they warm up, and the
gain with it. That might account for variations on a timescale of 100s ms.
Steve G8GSQ
On 11/03/2024 21:58, Jeff in Mali: via Amps wrote:
Hi Bill:
I've been pondering this question for a while, because it causes me problems in
working pileups. I miss the first letter or two and then the people come back
just once, so the same letter is missing again.
I saw the problem on my KPA 1500 just once last week as the first letters went
out at 400w or so and the rest at a KW. That's when I decided to post the
query. I'll check my own settings which are those which K4PI advised a long
time ago and I've never changed.
73,
Jeff
On Monday, March 11, 2024 at 08:47:30 PM GMT, hzp_electronics@juno.com
<hzp_electronics@juno.com> wrote:
Hi Jeff,
I think there are multiple reasons for the first character missing at the
beginning of a
transmission with an amplifier.
Number 1 reason: The sender is using an automatic band selection amplifier.
One amp,
can block 26ms from the beginning of RF input to the amp. This is "independent
of
the RF Delay setting" in the rig. This link provides an explanation.
https://qsk2
500.myfreesites.net/la-1k-qsk
ALL Automatic Band Selection amps have this problem in CW. Use rig control or
manual
band selection.
Number 2 reason: The RF delay in the rig from keying the amp until rig RF
output is less
than the amp T/R relay closing time. If not using automatic band selection in
the amp,
the RF Delay in the rig should be at least 15ms, preferably 20ms, for the amp
T/R relay
to settle.
I am sure there are other reasons. I did not know about the KPA-1500 amp power
ramp up?
Your hearing is not going bad!
73
.... Bill K3HZP
---------- Original Message ----------
From: Pete Smith N4ZR <pete.n4zr@gmail.com>
To: "amps@contesting.com" <amps@contesting.com>
Subject: Re: [Amps] Slow start-up of Amps on CW
Date: Mon, 11 Mar 2024 15:29:26 -0400
On the other hand, there are workarounds available. People started
telling me that my callsign was being clipped soon after I got my
KPA-1500 (my old SB-220 had homebrew QSK). I found lead-time settings
in my Winkeyer setup and in N1MM that let me delay CW until my amp was
up to speed (50 ms) and similarly hold-in after the last character was
sent. No more problems here.
I wondered if the pattern of busted spots on the RBN might also reflect
such issues, but so far, running together of characters - "TES TN4ZR" -
seems much more prevalent.
73, Pete N4ZR
On 3/11/2024 3:05 PM, Jeff in Mali: via Amps wrote:
Actually Bahamian stn from Spain.
On Monday, March 11, 2024 at 06:52:42 PM GMT, Jeff in
Mali:<tz4am@aol.com> wrote:
Then of course there is the famous Cayman station from Spain C6AAE.
On Monday, March 11, 2024 at 06:24:32 PM GMT, Jim
Brown<jim@audiosystemsgroup.com> wrote:
On 3/11/2024 7:57 AM, Jeff in Mali: via Amps wrote:
However, more and more I'm convinced that some amps are not
instantaneous, not picking up immediately as the first letter(s) is
(are) keyed on CW or spoken on SSB. The other night I was watchin my own
amp (Elecraft KPA-1500) and it seemed only to come up to full-power
after a few characters.
Is this a generalized phenomenon, or just my imagination?
R/T delay is quite real. When contesting, I regularly hear JA calls as
OA. It's not me mis-copying.
73, Jim K9YC
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