Posted by
markmusick on
Dec 11, 2019; 2:48am
URL: http://elecraft.85.s1.nabble.com/KPA-1500-ATU-operation-tp7656949p7656965.html
From page 24 of the KPA1500 manual:
Re-tuning to maintain a low SWR is normally required over a narrower frequency range on the lower frequencies. Band segments are:
• Below 4.8 MHz the segments are 10 kHz wide.
• From 4.8 MHz through 26 MHz the segments are 20 kHz wide.
• From 26 MHz to 38 MHz the segments are 100 kHz wide.
• Above 38 MHz the segments are 200 kHz wide.
Mark, WB9CIF
-----Original Message-----
From:
[hidden email] <
[hidden email]> On Behalf Of Bob McGraw K4TAX
Sent: Wednesday, December 11, 2019 02:08
To:
[hidden email]
Subject: Re: [Elecraft] KPA-1500 ATU operation
The ATU uses 10 kHz segments below 3 MHz. And then 20 kHz segments 3 MHz through 26 MHz. And 100 kHz segments from 38 MHz through 30 MHz. And 200 kHz segments 38 MHz through 60 MHz.
The understanding regarding 80M would then be the segments are 20 kHz wide and not 10 kHz wide.
73
Bob, K4TAX
On 12/10/2019 5:56 PM, K9MA wrote:
> I understand that the ATU uses 10 kHz segments on 80, which was at
> some point changed from 20 kHz. That means the center points are 3505,
> 3515, etc. There is some hysteresis when tuning, but I'm not sure that
> consistently explains where it switches. It also won't switch until
> you stop tuning for 1/2 second, or so.
>
> Another factor is that the ATU only measure frequency to, I think, 8
> kHz. The net result may be that sometimes it's not in the frequency
> segment you think it should be in. Unless you have a very narrow band
> antenna, it shouldn't make much difference.
>
> 73,
> Scott K9MA
>
>
>
> On 12/10/2019 17:03,
[hidden email] wrote:
>> After saving my KPA-1500 ATU impedance matching parameters on 80M at
>> 20 Kc intervals (3.510, 3.530, 3.550, 3.570, etc, etc), I expected
>> that the KPA-1500 ATU would automatically switch to the next set of
>> L/C values at the midpoint of the 20 Kc segments (like 3.520, 3.540,
>> 3.560, etc, etc), but I find that it switches randomly, sometimes
>> just 2 Kc away from the main tuning frequencies. Does anyone have
>> information on how the ATU is supposed to work when it is polling the
>> xcvr for frequency?
>>
>> Thanks, K5UA
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