[Amps] Slow start-up of Amps on CW

[Steve Thompson]

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 at juno.com <hzp_electronics at 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 at gmail.com>
> To: "amps at contesting.com" <amps at 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 at 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 at 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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