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KPA1500 Using Multiple Antennas With the Tuner

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Jim McCook W6YA

KPA1500 Using Multiple Antennas With the Tuner

I followed N4ZR’s thread and did not see a solution.I have the same
problem as Pete.I’ve got two antennas on 3 bands.I’ve put the tuner
settings in all the bins on those bands for each each antenna.Neither
antenna has SWR over 2.5:1.I can then step through the bins with RF on
each of those bands with ONE antenna with no problem.However, the tuner
settings were made with 40w.

If I am in a contest and decide to quickly change antennas to call
someone, the tuner doesn’t recognize the antenna change until RF is
applied.I apply the same drive power ~30w and before the tuner selects
the new setting, it sees the mismatch and output jumps to over 1700w,
high SWR is displayed, and a fault occurs.The only way I can avoid this
is first go to STBY, apply RF and wait for the new tuner setting to be
sensed and applied, then go back to OPER. To go back to the original
antenna I have to do that all over again. I don’t think this is how it’s
supposed to be, but I think there must be no solution.How can we go from
one antenna to another without this problem?73, Jim W6YA

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Jim McCook W6YA

KPA1500 Using Multiple Antennas With the Tuner

I meant to say the tuner settings were made with the KPA1500 in STBY
with the K3 TUNE PWR set to 40w. Jim
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David Box-2

Re: KPA1500 Using Multiple Antennas With the Tuner

If I am reading this thread correctly you have one coax from the KPA feeding a remote antenna switch. If correct how do you expect the KPA to know you switched?
de Dave K5MWR

On October 16, 2020 1:54:02 PM CDT, Jim McCook <[hidden email]> wrote:

>I meant to say the tuner settings were made with the KPA1500 in STBY
>with the K3 TUNE PWR set to 40w. Jim
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--
Sent from my Android device with K-9 Mail. Please excuse my brevity.
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Jim McCook W6YA

Re: KPA1500 Using Multiple Antennas With the Tuner

In reply to this post by Jim McCook W6YA

Dave, yes, one coax from the amp to a manual switch. Your question is
the same as mine. Somehow the KPA1500 should know by sensing a rise in
SWR and shutting down most of the drive power or output somehow so the
tuner can go through its motions without excessive output or a fault.

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David Box-2

Re: KPA1500 Using Multiple Antennas With the Tuner

Jim, If it is a manual switch then must be a short run from KPA to switch so why not connect to ANT1 ANT2 on KPA and switch with KPA. KPA stores separate solutions for each ANT.
de Dave K5MWR

On October 16, 2020 2:26:13 PM CDT, Jim McCook <[hidden email]> wrote:

>Dave, yes, one coax from the amp to a manual switch. Your question is
>the same as mine. Somehow the KPA1500 should know by sensing a rise in
>
>SWR and shutting down most of the drive power or output somehow so the
>tuner can go through its motions without excessive output or a fault.
>
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Jim Brown-10

Re: KPA1500 Using Multiple Antennas With the Tuner

In reply to this post by Jim McCook W6YA

On 10/16/2020 12:26 PM, Jim McCook wrote:
> Dave, yes, one coax from the amp to a manual switch. Your question is
> the same as mine. Somehow the KPA1500 should know by sensing a rise in
> SWR and shutting down most of the drive power or output somehow so the
> tuner can go through its motions without excessive output or a fault.

I'm doing the same thing you are, Jim -- a dozen or so antennas, often 2
or 3 for the same band. I've been lazy about training the KPA1500, but
it is smart enough to switch between saved tunings within a reasonable
range.

I suspect that, to have the system automatically change power in the
manner that Pete needs, Elecraft would need to write software to
remember and change drive levels from the transceiver on command from
the KPA1500.

My solution is an LP100A with sensors inline with the amp outputs from
both stations in my SO2R setup, and I manually adjust drive levels as
needed. The LO100A is positioned right in front of me, so I can't miss
it, and I have it set for peak hold, which gives me a worst case number
for power out. My K3s do a bit of power hunting when I adjust power,
starting high on the first dits and dropping back to the intended
setting, so I often need to do multiple tweaks of drive level to get up
to legal limit.

73, Jim K9YC

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David Box-2

Re: KPA1500 Using Multiple Antennas With the Tuner

In reply to this post by David Box-2

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N4ZR

Re: KPA1500 Using Multiple Antennas With the Tuner

In reply to this post by Jim Brown-10

Precisely what I thought, Jim. The KPA-1500 already adjusts the K3's
output power when the amp switches to OPER, from 100 watts in STBY to a
preset, much lower value in OPER, but I don't know if they can store and
recall drive power levels by band and antenna

73, Pete N4ZR
Check out the Reverse Beacon Network
at <http://reversebeacon.net>, now
spotting RTTY activity worldwide.
For spots, please use your favorite
"retail" DX cluster.

On 10/16/2020 3:54 PM, Jim Brown wrote:
>
> ...I suspect that, to have the system automatically change power in
> the manner that Pete needs, Elecraft would need to write software to
> remember and change drive levels from the transceiver on command from
> the KPA1500.
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K8TE

Re: KPA1500 Using Multiple Antennas With the Tuner

I too have the same issue. I worked with Dick on this, but there is no
solution currently available when using an external antenna switch
(necessary with more than two antennas) with the KPA1500. Unfortunately,
there is no way for the KPA1500 to tell the K3/K3S to use a different drive
level, even when using ANT1 and ANT2 on the same band, but with two
different antennas that require different tuning solutions.

My (not yet implemented) initial solution is to use a macro for band changes
that will drop the drive level based on previously-determined data when
selecting a new band/antenna. The long term solutions is a computer (Pi,
Arduino, PC, etc.) with the appropriate tables with the data entered from
empirical testing. I only wish the ability (firmware and hardware) had been
included in the original design.

I'll take my KPA1500 to Lubbock next weekend for the CQ WW DX SSB Contest.
I reconfigure the station's antenna switching to use ANT1 and ANT2 in the
KPA1500. I carefully choose antennas by band so the two ports use the same
antennas by band and train the KPA1500 tuner appropriately. The KPA1500 and
2x8 antenna switch follow the IC-7610 band and frequency data. The hardest
part is prying the KPA1500 out of the station owner's hands so I can take it
back home!

Anyone with near perfect antenna systems (minimal tuning solutions needed)
won't have this problem. Maybe I'll get there someday? As Rosana
Rosanadana used to say: "It's always something." (not the same without
Gilda Radner voicing it!)

73, Bill, K8TE

P.S. I have also noticed a big (300-400 Watts) difference in output after a
"long" pause in use (15-30 minutes) along with the difference between
antenna solutions on the two ports for the same frequency.

--
Sent from: http://elecraft.365791.n2.nabble.com/
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Dick Dievendorff-4

Re: KPA1500 Using Multiple Antennas With the Tuner

In reply to this post by N4ZR

Your K3 stores the power settings. The amp reports when it goes in and out of OPER and the K3 (and K4) store two power settings per band, one for the amp in STBY, another for amp in OPER. You adjust these levels at the exciter, and they’re retained for recall on band switch and power off/on. Mine are typically 100w for amp in STBY and 25-35w for amp in OPER. I’m primarily a CW guy, but in digital modes I often drop down to see who I can reach with good antennas and little power.

There are K3 and K4 menu choices for “Per band power” to enable this.

73 de Dick, K6KR

> On Oct 16, 2020, at 19:09, N4ZR <[hidden email]> wrote:
>
> Precisely what I thought, Jim. The KPA-1500 already adjusts the K3's output power when the amp switches to OPER, from 100 watts in STBY to a preset, much lower value in OPER, but I don't know if they can store and recall drive power levels by band and antenna
>
> 73, Pete N4ZR
> Check out the Reverse Beacon Network
> at <http://reversebeacon.net>, now
> spotting RTTY activity worldwide.
> For spots, please use your favorite
> "retail" DX cluster.
>
>> On 10/16/2020 3:54 PM, Jim Brown wrote:
>>
>> ...I suspect that, to have the system automatically change power in the manner that Pete needs, Elecraft would need to write software to remember and change drive levels from the transceiver on command from the KPA1500.
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Jim Brown-10

Re: KPA1500 Using Multiple Antennas With the Tuner

In reply to this post by K8TE

On 10/16/2020 7:39 PM, K8TE wrote:
> there is no
> solution currently available when using an external antenna switch
> (necessary with more than two antennas) with the KPA1500.

I see it as an issue only when using more than one antenna ON THE SAME
BAND. I have two antennas for 30, 20, 15, and 10M, and three antennas
for 160, 80, and 40M. My antenna switching system was developed for the
KAT500. My long 6M Yagi goes to port #2.

Unfortunately,

> there is no way for the KPA1500 to tell the K3/K3S to use a different drive
> level, even when using ANT1 and ANT2 on the same band, but with two
> different antennas that require different tuning solutions.
>
> My (not yet implemented) initial solution is to use a macro for band changes
> that will drop the drive level based on previously-determined data when
> selecting a new band/antenna. The long term solutions is a computer (Pi,
> Arduino, PC, etc.) with the appropriate tables with the data entered from
> empirical testing. I only wish the ability (firmware and hardware) had been
> included in the original design.

Yes, that's unfortunate. I think Dick has done a great job with the
tuner design, with it's capability to switch between multiple trained
settings for every frequency!

73, Jim K9YC
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N4ZR

Re: KPA1500 Using Multiple Antennas With the Tuner

In reply to this post by Dick Dievendorff-4

I agree, Dick - power settings per band are fine. The issue is power
settings per band and per matching solution

73, Pete N4ZR
Check out the Reverse Beacon Network
at <http://reversebeacon.net>, now
spotting RTTY activity worldwide.
For spots, please use your favorite
"retail" DX cluster.

On 10/16/2020 11:01 PM, Dick Dievendorff wrote:

> Your K3 stores the power settings. The amp reports when it goes in and out of OPER and the K3 (and K4) store two power settings per band, one for the amp in STBY, another for amp in OPER. You adjust these levels at the exciter, and they’re retained for recall on band switch and power off/on. Mine are typically 100w for amp in STBY and 25-35w for amp in OPER. I’m primarily a CW guy, but in digital modes I often drop down to see who I can reach with good antennas and little power.
>
> There are K3 and K4 menu choices for “Per band power” to enable this.
>
> 73 de Dick, K6KR
>
>> On Oct 16, 2020, at 19:09, N4ZR <[hidden email]> wrote:
>>
>> Precisely what I thought, Jim. The KPA-1500 already adjusts the K3's output power when the amp switches to OPER, from 100 watts in STBY to a preset, much lower value in OPER, but I don't know if they can store and recall drive power levels by band and antenna
>>
>> 73, Pete N4ZR
>> Check out the Reverse Beacon Network
>> at <http://reversebeacon.net>, now
>> spotting RTTY activity worldwide.
>> For spots, please use your favorite
>> "retail" DX cluster.
>>
>>> On 10/16/2020 3:54 PM, Jim Brown wrote:
>>>
>>> ...I suspect that, to have the system automatically change power in the manner that Pete needs, Elecraft would need to write software to remember and change drive levels from the transceiver on command from the KPA1500.
>> ______________________________________________________________
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