[Amps] Slow start-up of Amps on CW

hzp_electronics at juno.com hzp_electronics at juno.com
Mon Mar 11 13:40:15 EDT 2024


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://qsk2500.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: "Jeff in Mali: via Amps" <amps at contesting.com>
To: "amps at contesting.com" <amps at contesting.com>
Subject: [Amps] Slow start-up of Amps on CW
Date: Mon, 11 Mar 2024 14:57:01 +0000 (UTC)

Dear All:
I find that on CW, I miss the first letter or two letters of people's call. I thought that it was just me not paying attention or half-deaf from too many years cutting grass as a kid with lawn-mowers with no mufflers. 
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?
73, 
JeffTZ4AM/K1MMBBamako, Mali 
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