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KPA500/KAT500 paired with AL-1500?

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Jim AB3CV

KPA500/KAT500 paired with AL-1500?

I'm considering adding a bigger amp to the shack. I'd like to continue to
use the KPA/KAT combo for quick hits and the bigger amp if/when needed. So
I'd like to make it convenient to switch between them.

The people I've talked to so far actually move coax to make the switch. I'd
like to avoid that.

I'd need to switch the K3s output from the KPA to the AL1500 and obviously
switch the outputs as well.

Obviously I'd also need to set the non-KPA power out of the K3 to the per
band power needed by the AL1500. I seldom run 100w so that wouldn't be a
big deal.

I'd love to hear from anyone who has done this without screwing/unscrewing
UHF connectors.

Extra credit for idiot proofing. ;-)

73

jim ab3cv
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Jim Brown-10

Re: KPA500/KAT500 paired with AL-1500?

Hi Jim,

I'm doing exactly that, but with a Ten Tec Titan 425 rather than the
1500. My method is pretty simple -- I'm using two of W2VJN's 1x2 Top Ten
relay boxes, one at the inputs, the other at the outputs. They work
well, except that the SWR is pretty poor on 6M (and is starting to rise
on 10M) because these boxes use the chassis as the signal return rather
than carrying it on the circuit board. To clarify, only a single wire
goes from each coax connector to the circuit board. And even if the
shield was carried, the return layer is broken on the return layer.

I put a "band-aid" on the SWR problem by adding the return path, and by
adding a small stub on the output of the switch on the KPA500 side. To
add the return path, you need to run a short piece of braid from each
coax connector to the circuit board near where the center conductor is
terminated, and add short sections of braid across the board following
the signal path from input to each of the outputs. That reduces the SWR
by half, the stub finishes it off.

Other vendors make similar boxes, but I haven't seen them, so I don't
know if they do the signal return correctly or not. I don't recall the
exact length of the stub, but I think I recall that the alternative was
a cap of about 11 pF.

73, Jim K9YC

On Sat,10/22/2016 4:12 PM, Jim Miller wrote:

> I'm considering adding a bigger amp to the shack. I'd like to continue to
> use the KPA/KAT combo for quick hits and the bigger amp if/when needed. So
> I'd like to make it convenient to switch between them.
>
> The people I've talked to so far actually move coax to make the switch. I'd
> like to avoid that.
>
> I'd need to switch the K3s output from the KPA to the AL1500 and obviously
> switch the outputs as well.
>
> Obviously I'd also need to set the non-KPA power out of the K3 to the per
> band power needed by the AL1500. I seldom run 100w so that wouldn't be a
> big deal.
>
> I'd love to hear from anyone who has done this without screwing/unscrewing
> UHF connectors.
>
> Extra credit for idiot proofing. ;-)
>
> 73
>
> jim ab3cv
> ______________________________________________________________
> Elecraft mailing list
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>

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markmusick

Re: KPA500/KAT500 paired with AL-1500?

In reply to this post by Jim AB3CV

I do this with my Alpha 9500. But differently than K9YC.
I use the two antenna ports on the K3 and an Alpha Delta 2 position switch.
Antenna one on the K3 goes to the KPA500 input. Antenna 2 on the K3 goes to
the 9500 input.
The output of the KPA500 goes to position one on the Alpha Delta switch. The
output of the 9500 goes to position two of the Alpha Delta switch. The
common of the Alpha Delta switch goes to the antenna switch.
When I want the KPA500 the K3 is on ANT1 and the Alpha Delta switch is on
position one.
When I want the 9500 the K3 is on ANT2 and the Alpha Delta switch is on
position two.
Since the K3 remembers power by band and antenna, when I'm on the KPA500
regardless of band it has the correct power setting to give me 500 Watts or
200 Watts on 30 meters. When I'm on the 9500 the K3 has the correct drive
power for the 9500 for that band.
That is how I do it and it works for me.

Mark, WB9CIF

-----Original Message-----
From: Elecraft [mailto:[hidden email]] On Behalf Of Jim
Miller
Sent: Saturday, October 22, 2016 11:12 PM
To: Elecraft Reflector <[hidden email]>
Subject: [Elecraft] KPA500/KAT500 paired with AL-1500?

I'm considering adding a bigger amp to the shack. I'd like to continue to
use the KPA/KAT combo for quick hits and the bigger amp if/when needed. So
I'd like to make it convenient to switch between them.

The people I've talked to so far actually move coax to make the switch. I'd
like to avoid that.

I'd need to switch the K3s output from the KPA to the AL1500 and obviously
switch the outputs as well.

Obviously I'd also need to set the non-KPA power out of the K3 to the per
band power needed by the AL1500. I seldom run 100w so that wouldn't be a big
deal.

I'd love to hear from anyone who has done this without screwing/unscrewing
UHF connectors.

Extra credit for idiot proofing. ;-)

73

jim ab3cv
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N7US

Re: KPA500/KAT500 paired with AL-1500?

In reply to this post by Jim AB3CV

I have a KPA500/KAT500 and an 87A/ATR-30 tuner connected to my K3. Not
important, but I have an Array Solutions Power Master II wattmeter with two
couplers connected to the amplifiers' outputs.

My approach is pretty low tech. I have the 87A connected to the K3's ANT2
port and the KPA500 connected to ANT1. I use an Alpha Delta manual coax
switch to switch my only antenna coax between the two amplifiers. (I
considered using a spare Daiwa switch but it's not rated at 1500W.) I
looked up the inter-port isolation for the antenna switch when I connected
it, and it seemed adequate, but I don't remember the specs.

The only thing that's a bit fancy is a macro I did recently to use in my
K-Pod. I don't switch amplifiers often so I used two press-and-hold buttons
on the K-Pod.

KPA500 MN058;MP123;MN081;UP;MN255;AN1;

87A MN058;MP000;MN081;UP;MN255;AN2;

You can either look through the K3 Programmer's Reference Manual if you want
the mental exercise or read my notes below:

MN058 - menu

MP123 - sets K3's tune power to 15W (just my preference).

MP000 - sets K3 tune power to NOR (not per band)

MN081 - toggles between per band power for the KPA500 or NOR for the 87A.

MN255 - exits the menu

AN1/AN2 - selects antenna 1 or 2.

73, Jim N7US

-----Original Message-----

I'm considering adding a bigger amp to the shack. I'd like to continue to
use the KPA/KAT combo for quick hits and the bigger amp if/when needed. So
I'd like to make it convenient to switch between them.

The people I've talked to so far actually move coax to make the switch. I'd
like to avoid that.

I'd need to switch the K3s output from the KPA to the AL1500 and obviously
switch the outputs as well.

Obviously I'd also need to set the non-KPA power out of the K3 to the per
band power needed by the AL1500. I seldom run 100w so that wouldn't be a big
deal.

I'd love to hear from anyone who has done this without screwing/unscrewing
UHF connectors.

Extra credit for idiot proofing. ;-)

73

jim ab3cv

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george allen

Re: KPA500/KAT500 paired with AL-1500?

In reply to this post by Jim AB3CV

I have built a switch to switch radios to a particular antennas to take to our club shack. The best isolation I could get was 37dbm. Not good enough, so we are moving a jumper between UHF connectors.

Sent from my iPad

> On Oct 22, 2016, at 7:12 PM, Jim Miller <[hidden email]> wrote:
>
> I'm considering adding a bigger amp to the shack. I'd like to continue to
> use the KPA/KAT combo for quick hits and the bigger amp if/when needed. So
> I'd like to make it convenient to switch between them.
>
> The people I've talked to so far actually move coax to make the switch. I'd
> like to avoid that.
>
> I'd need to switch the K3s output from the KPA to the AL1500 and obviously
> switch the outputs as well.
>
> Obviously I'd also need to set the non-KPA power out of the K3 to the per
> band power needed by the AL1500. I seldom run 100w so that wouldn't be a
> big deal.
>
> I'd love to hear from anyone who has done this without screwing/unscrewing
> UHF connectors.
>
> Extra credit for idiot proofing. ;-)
>
> 73
>
> jim ab3cv
> ______________________________________________________________
> Elecraft mailing list
> Home: http://mailman.qth.net/mailman/listinfo/elecraft
> Help: http://mailman.qth.net/mmfaq.htm
> Post: mailto:[hidden email]
>
> This list hosted by: http://www.qsl.net
> Please help support this email list: http://www.qsl.net/donate.html
> Message delivered to [hidden email]

k6dgw

Re: KPA500/KAT500 paired with AL-1500?

Ahhh yes. DC is so much easier to switch, unless you start an arc of
course.

73,

Fred K6DGW
- Sparks NV DM09dn

- Northern California Contest Club
- CU in the Cal QSO Party 7-8 Oct 2017
- www.cqp.org

On 10/22/2016 7:02 PM, george allen wrote:
> I have built a switch to switch radios to a particular antennas to
> take to our club shack. The best isolation I could get was 37dbm.
> Not good enough, so we are moving a jumper between UHF connectors.
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Vic Rosenthal

Re: KPA500/KAT500 paired with AL-1500?

In reply to this post by N7US

I used to switch two amps. I used a pair of surplus coaxial relays to switch the inputs and outputs. I have my amps set up with a 12v 'enable' input which operates a relay to put the amp in standby or operate mode, and the switch that operated the relays also switched this line. I simply isolated the amp key lines with diodes, because when the amp was in standby, the key line was disabled.
Just some ideas.

Vic 4X6GP

> On 23 Oct 2016, at 03:11, Jim McDonald <[hidden email]> wrote:
>
> I have a KPA500/KAT500 and an 87A/ATR-30 tuner connected to my K3. Not
> important, but I have an Array Solutions Power Master II wattmeter with two
> couplers connected to the amplifiers' outputs.
>
> My approach is pretty low tech. I have the 87A connected to the K3's ANT2
> port and the KPA500 connected to ANT1. I use an Alpha Delta manual coax
> switch to switch my only antenna coax between the two amplifiers. (I
> considered using a spare Daiwa switch but it's not rated at 1500W.) I
> looked up the inter-port isolation for the antenna switch when I connected
> it, and it seemed adequate, but I don't remember the specs.
>
> The only thing that's a bit fancy is a macro I did recently to use in my
> K-Pod. I don't switch amplifiers often so I used two press-and-hold buttons
> on the K-Pod.
>
> KPA500 MN058;MP123;MN081;UP;MN255;AN1;
>
> 87A MN058;MP000;MN081;UP;MN255;AN2;
>
> You can either look through the K3 Programmer's Reference Manual if you want
> the mental exercise or read my notes below:
>
> MN058 - menu
>
> MP123 - sets K3's tune power to 15W (just my preference).
>
> MP000 - sets K3 tune power to NOR (not per band)
>
> MN081 - toggles between per band power for the KPA500 or NOR for the 87A.
>
> MN255 - exits the menu
>
> AN1/AN2 - selects antenna 1 or 2.
>
> 73, Jim N7US
>
>
> -----Original Message-----
>
> I'm considering adding a bigger amp to the shack. I'd like to continue to
> use the KPA/KAT combo for quick hits and the bigger amp if/when needed. So
> I'd like to make it convenient to switch between them.
>
> The people I've talked to so far actually move coax to make the switch. I'd
> like to avoid that.
>
> I'd need to switch the K3s output from the KPA to the AL1500 and obviously
> switch the outputs as well.
>
> Obviously I'd also need to set the non-KPA power out of the K3 to the per
> band power needed by the AL1500. I seldom run 100w so that wouldn't be a big
> deal.
>
> I'd love to hear from anyone who has done this without screwing/unscrewing
> UHF connectors.
>
> Extra credit for idiot proofing. ;-)
>
> 73
>
> jim ab3cv
>
>
> ______________________________________________________________
> Elecraft mailing list
> Home: http://mailman.qth.net/mailman/listinfo/elecraft
> Help: http://mailman.qth.net/mmfaq.htm
> Post: mailto:[hidden email]
>
> This list hosted by: http://www.qsl.net
> Please help support this email list: http://www.qsl.net/donate.html
> Message delivered to [hidden email]

Edward R Cole

Re: KPA500/KAT500 paired with AL-1500?

In reply to this post by Jim AB3CV

Not sure this would work for your application, but I recently
installed a DowKey 412-2301 Transfer Relay in my 6m system to switch
in my Harris 1kW 6m amp or to bypass it. Might require a couple
relays for this to work with two amplifiers.
http://www.kl7uw.com/2016_Station.jpg

The DowKey relay is rated to 2000w at 6m.

73, Ed - KL7UW
http://www.kl7uw.com
"Kits made by KL7UW"
Dubus Mag business:
[hidden email]

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Joe Subich, W4TV-4

Re: KPA500/KAT500 paired with AL-1500?

A pair of the Tohtsu CX-600NL relays from Surplus Sales of Nebraska
<https://www.surplussales.com/Relays/rfcoaxialrelays/rfcoax_n.html>
should work just fine. It would likely take a pair of transfer relays
- one on the input and one on the output of the amplifiers to do the
same thing.

The only advantage of transfer relays is that the unused amplifier
could be kept terminated in a dummy load.

73,

... Joe, W4TV

On 10/23/2016 4:59 AM, Edward R Cole wrote:

> Not sure this would work for your application, but I recently installed
> a DowKey 412-2301 Transfer Relay in my 6m system to switch in my Harris
> 1kW 6m amp or to bypass it. Might require a couple relays for this to
> work with two amplifiers.
> http://www.kl7uw.com/2016_Station.jpg
>
> The DowKey relay is rated to 2000w at 6m.
>
> 73, Ed - KL7UW
> http://www.kl7uw.com
> "Kits made by KL7UW"
> Dubus Mag business:
> [hidden email]
>

N7US

Re: KPA500/KAT500 paired with AL-1500?

The Alpha Delta switch that I use on the output of my KPA500 and 87A grounds
unused connectors. Thus my KPA500's antenna port is grounded if I am using
the 87A and vice versa.

73, Jim N7US

-----Original Message-----

A pair of the Tohtsu CX-600NL relays from Surplus Sales of Nebraska
<https://www.surplussales.com/Relays/rfcoaxialrelays/rfcoax_n.html>
should work just fine. It would likely take a pair of transfer relays
- one on the input and one on the output of the amplifiers to do the same
thing.

The only advantage of transfer relays is that the unused amplifier could be
kept terminated in a dummy load.

73,

... Joe, W4TV

On 10/23/2016 4:59 AM, Edward R Cole wrote:
> Not sure this would work for your application, but I recently
> installed a DowKey 412-2301 Transfer Relay in my 6m system to switch
> in my Harris 1kW 6m amp or to bypass it. Might require a couple
> relays for this to work with two amplifiers.
> http://www.kl7uw.com/2016_Station.jpg
>
> The DowKey relay is rated to 2000w at 6m.
>
> 73, Ed - KL7UW

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Edward R Cole

Re: KPA500/KAT500 paired with AL-1500?

In reply to this post by Jim AB3CV

Just warning about the CX-600NL. I initially used them for TR relays
on 2m-eme at 100w to 600w with no problems but once I increased power
to >800w the relays began to fail. The contacts apparently not able
to carry higher RF current as they eventually heat and melt the
center wiper usually such that it shorts the coaxial section -- Not a
nice thing to do to a 1500w amp. As I said I have had three fail this way.

I use sequencing so absolutely not due to hot switching (at least
30msec delay before RF applied).

Maybe they will handle HF power better (I do not have HF QRO). Also
when running 2m-eme my 8877 is key down for 50-seconds under JT65 and
key up for 70-seconds, which repeats as long as in transmit. So this
is "almost" Alpha brick testing!

When one of the relays shorted I noted that my 8877 output went to
1800w and drew over an amp at 3000v. Fortunately I noted this
quickly and shut it down. Grid current was higher but apparently no
harm to the 8877 (what a really tough tube -- I have eight years
running on the same tube). I use a G3SEK Triode Board for bias,
warm-up delay and overcurrent protection for both anode and grid.

Two coax relays probably work as well as a transfer relay for the two
amp application. Make sure the output relay can handle the max power.

I have one surviving CX600NL which is used to select either 1296 amp
or 900 amp at my tower top (both low power level drive input for the
amps). I now use NARDA sem123N (1200w at 150-MHz) in the high power ckts.

73, Ed -KL7UW

From: "Joe Subich, W4TV" <[hidden email]>
To: [hidden email]
Subject: Re: [Elecraft] KPA500/KAT500 paired with AL-1500?
Message-ID: <[hidden email]>
Content-Type: text/plain; charset=utf-8; format=flowed

A pair of the Tohtsu CX-600NL relays from Surplus Sales of Nebraska
<https://www.surplussales.com/Relays/rfcoaxialrelays/rfcoax_n.html>
should work just fine. It would likely take a pair of transfer relays
- one on the input and one on the output of the amplifiers to do the
same thing.

The only advantage of transfer relays is that the unused amplifier
could be kept terminated in a dummy load.

73,

... Joe, W4TV

73, Ed - KL7UW
http://www.kl7uw.com
"Kits made by KL7UW"
Dubus Mag business:
[hidden email]

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