I'm not clear whether you are talking about the SWR before or after the
tuner, but efficiency is determined by the load seen by the PA, which
has two degrees of freedom (reactance and resistance), both of which can
vary either side of the ideal. SWR reduces this to a single variable,
that
: [Elecraft] KPA-1500 ATU not working well
Here is a picture and some plot images:
http://www.kn5l.net/Elecraft/CP1/
Not super accurate 60 and 100 Ohm loads, but provides an insight of the coupler
operation.
John KN5L
On 06/22/2018 04:15 PM, Wes Stewart wrote:
> I don't quite understand y
Hi John,
Well if a picture is worth a thousand words a graph is worth at least
10,000.
THANKS for the posting!
73,
Bob
K2TK ex KN2TKR (1956) & K2TKR
On 6/22/2018 6:27 PM, John Oppenheimer wrote:
Here is a picture and some plot images:
http://www.kn5l.net/Elecraft/CP1/
Not
Offhand, since they are adamantly opposed to using operational ALC, I could see
incorporating a "1500 W" gain calibration, as they do with K3s. They could read
the output power at several frequencies per band and save the gain settings.
This assumes they have enough memory in the K3 to save
Here is a picture and some plot images:
http://www.kn5l.net/Elecraft/CP1/
Not super accurate 60 and 100 Ohm loads, but provides an insight of the
coupler operation.
John KN5L
On 06/22/2018 04:15 PM, Wes Stewart wrote:
> I don't quite understand your methodology but there is one, apparently
KX3, KXPA100, KAT500, W2, etc.
-Original Message-
From: elecraft-boun...@mailman.qth.net On
Behalf Of Wes Stewart
Sent: Friday, June 22, 2018 3:45 PM
To: Paul Baldock ; elecraft@mailman.qth.net
Subject: Re: [Elecraft] KPA-1500 ATU not working well
OK, note my quali
My observation , also.
Another approach would be for automatic drive adjustment, or ALC that worked.
The latter, I know, is very difficult to do with an amp.
Scott K9MA
--
Scott Ellington
--- via iPad
> On Jun 22, 2018, at 2:36 PM, Paul Baldock wrote:
>
> I have found that if
I don't quite understand your methodology but there is one, apparently little
known caveat with the use of the "Elecraft" coupler topology. AFAIK, this was
first used by John Grebenkemper, KI6WX, in his Tandem Match, described in QST,
January 1987.
Paul Kiciak, N2PK, mentions in his paper,
OK, note my qualifier, "If". If there are other detrimental issues with greater
load mismatch then they might need to be addressed. Unfortunately, Elecraft
doesn't specify a load requirement for rated output. Gain ripple that you
observe is possibly a reflection (no pun intended) of the LPFs
Putting the Elecraft CP1 through the paces with a 2 port VNA can be
enlightening. The CP1 seems to be representative of Elecraft directional
couplers across the line. There's a picture of the W2 high power HF
coupler in the manual, it's just larger cores.
Sweeping a 20 dB CP1 across the band with
"If 1.5:1 does this, then that's good enough in my book. Furthermore, a
better match might entail higher tuner losses. So why worry about it?
My test data for my KPA500 show there is a very significant difference in PA
dissipation and also in harmonic output for loads giving indicated 1.4:1
I have found that if the KPA1500 is feeding a
largish SWR (like 1.5:1 as you suggest) then the
drive power required to maintain a constant
output will vary significantly as you tune across
a band. This means you have to keep adjusting the
power control within a single band. This appears
not
I do not, and probably never will, have a KPA1500. I do have a KPA500 and
KAT500 so I think I can comment. In my opinion, the function of these tuners is
to provide a match into which the amp can deliver full power. If 1.5:1 does
this, then that's good enough in my book. Furthermore, a
At 09:28 AM 6/22/2018, K9MA wrote:
That would explain why I sometimes hear the
relays click again when I transmit (I think).
Seems that could be fixed by simply requiring
that the difference be more than, say, 20 kHz
before the counter takes priority.
Scott K9MA
You are not imagining
That would explain why I sometimes hear the relays click again when I
transmit (I think). Seems that could be fixed by simply requiring that
the difference be more than, say, 20 kHz before the counter takes priority.
Scott K9MA
On 6/22/2018 11:00, Paul Baldock wrote:
True, it then double
True, it then double checks with the internal
frequency counter once rf is applied, and may
choose a different segment if the internal counter disagrees.
- Paul
At 08:48 AM 6/22/2018, K9MA wrote:
But wait! I know I hear the ATU relays switch
when I stop tuning the K3, before transmitting.
But wait! I know I hear the ATU relays switch when I stop tuning the K3,
before transmitting.
Scott K9MA
On 6/22/2018 10:01, Paul Baldock wrote:
They want to be certain that the amp is on the correct band, should
the data from the radio be incorrect.
- Paul KW7Y
I wonder why this is so.
"It might be but the amp is designed to work with radios other than K3s."
The KPA1500 and KPA500 are both capable of receiving frequency from
transceivers other than the K3S, so is the KAT500. I don't see how not using a
K3S puts any limitation on my proposal.
73,
Andy k3wyc
They want to be certain that the amp is on the correct band, should
the data from the radio be incorrect.
- Paul KW7Y
I wonder why this is so.
Scott K9MA
--
Scott Ellington
--- via iPad
> On Jun 22, 2018, at 1:17 AM, Paul Baldock wrote:
>
> frequency counter measurement, not
Andy -
Sounds like a great idea.
- Paul
6/22/2018, ANDY DURBIN wrote:
"Clearly there has to be some hysteresis to stop hunting. 25% of a
segment width might width be a good number to choose, but this would
require the current frequency counter to have improved resolution."
Why wouldn't it
I wonder why this is so.
Scott K9MA
--
Scott Ellington
--- via iPad
> On Jun 22, 2018, at 1:17 AM, Paul Baldock wrote:
>
> frequency counter measurement, not the frequency you transceiver sends to the
> KPA1500.
__
It might be but the amp is designed to work with radios other than K3s.
On 6/22/2018 5:01 AM, ANDY DURBIN wrote:
Why wouldn't it be preferable to use the transceiver's exact TX frequency, if
available,
__
Elecraft mailing list
Home:
"Clearly there has to be some hysteresis to stop hunting. 25% of a segment
width might width be a good number to choose, but this would require the
current frequency counter to have improved resolution."
Why wouldn't it be preferable to use the transceiver's exact TX frequency, if
available,
First let me say that other than some issues with
the ATU, I am after a week of use, very happy with the KPA1500.
So here's the ATU issues:
I find that the ATU very rarely will learn a
setting to get the SWR below 1.2:1 on any band. I
can usually tweak it down to 1.0:1 using the
Utility
Hi,
I am currently out of the office until July 1, 2018.
If you purchased a license, and have not received it, it is almost 100% sure to
be in your spam, junk or other such folder. In Gmail it will be in the web
version of gmail. Please check for it there.
All my websites have a section
Dick,
Have you tried manually adjusting the ATU? I haven't used mine on 6
meters, but on other bands, no matter what I do, it sometimes doesn't
get a very good match automatically, and I can do better manually. On
the other hand, it may be that the L and C step sizes are just too big
to
I'm wondering if anyone else is having problems with their KPA-1500 ATU on
6-meters? My antenna is cut for 50.100 and has a 2.2:1 SWR at the 50.313 FT-8
frequency. The very best the ATU will do is to lower the SWR from 2.2:1 down
to 2.0:1 which is almost no improvement. The 2.0 to 1 is with
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