KPA500 switching ideas with a Flex-5000A?

[Edward R Cole]

I copied the wrong part number on the Surplus sales site:
s/b  (KC) 12W1008 as the least expensive cross-over relay rated for >1kW

the CX800M has UHF connectors and works on 12vdc, whereas the relay
above is N-connectors and requires 28vdc.


73, Ed - KL7UW, WD2XSH/45
======================================
BP40IQ   500 KHz - 10-GHz   www.kl7uw.com
EME: 50-1.1kw?, 144-1.4kw, 432-100w, 1296-60w, 3400-?
DUBUS Magazine USA Rep [hidden email]
======================================

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[Dick Dievendorff]

This seems awfully expensive.

Array Solutions doesn't spend that much for the relays inside their Six Pak.

Top Ten devices doesn't spend that much for the SPDT relay inside their A/B
station selector.  That unit goes for $77, and that includes a nice box and
the connectors.

The T/R switch within my Ameritron AL-1200 doesn't cost that much.

Wouldn't a sealed or frame relay do the job?  600 watts into a 50 ohm
resistive load is 12 Amps.  20A DPDT frame relays can be acquired for a lot
less than a coaxial relay.

SPST relays cost even less.  KK1L uses relays that are advertised at about
$3.16 each in his 2 x 6 antenna switch.

Is it necessary to operate concurrently on HF and 6 meters?  Wouldn't a
couple of SPST relays suffice for this application?

100 watts into 50 ohms is 2A. You can use a much smaller relay on the 100
watt exciter to amplifier side. I'd use 5A relay.

73 de Dick, K6KR


> That can be accomplished with three DPDT coaxial relays such as the CX800M
($159/ea from http://www.rfparts.com/coaxial.html ) $477 total

> It can be done with two coaxial transfer switches but probably cost more
(KC 1420-820 from
http://www.surplussales.com/Relays/rfcoaxialrelays/rfcoax_n.html

are $275/ea. ($550 total)

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[Greg - AB7R]

Another option is a fun kit to build designed by KK1L.  It is a 2x6 antenna
switch and SO2R band decoder board.  The external switch has two inputs.
This will allow you to put the amp inline with ANT1 and ANT2 straight to the
second input.  You can than select up to 6 antennas for either output.  It
has very good isolation and is not difficult to build.

You can also set it up to auto select antennas by using BCD decoding from
the LPT port.

73
Greg
AB7R


On Thu, Jul 14, 2011 at 1:36 AM, Edward R. Cole <[hidden email]> wrote:

> I copied the wrong part number on the Surplus sales site:
> s/b  (KC) 12W1008 as the least expensive cross-over relay rated for >1kW
>
> the CX800M has UHF connectors and works on 12vdc, whereas the relay
> above is N-connectors and requires 28vdc.
>
>
> 73, Ed - KL7UW, WD2XSH/45
> ======================================
> BP40IQ   500 KHz - 10-GHz   www.kl7uw.com
> EME: 50-1.1kw?, 144-1.4kw, 432-100w, 1296-60w, 3400-?
> DUBUS Magazine USA Rep [hidden email]
> ======================================
>
> ______________________________________________________________
> 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
>

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[Tony Estep]

On Thu, Jul 14, 2011 at 9:40 AM, Dick Dievendorff <[hidden email]>wrote:

> ...Array Solutions doesn't spend that much for the relays inside their Six
> Pak....


Here's a very interesting reference for relays used in just this
application, along with part number and a picture:

http://www.w8zr.net/stationpro/index.htm

Tony KT0NY
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[Joe Subich, W4TV-4]

 > This seems awfully expensive.

It is - but the Totsu DPDT coaxial or other transfer relays are
an off the shelf solution.  The Totsu solution can be simplified
to two relays by careful choice if cable lengths and adding a
couple compensating stubs in the "amplifier" leg.

One can certainly spend a lot less if he is willing (and has the
ability) to design strip line circuit boards for off the shelf
relays.  This isn't an application where one can simply take
three DPDT or six SPDT "power" relays, nail them to a breadboard
and solder random lengths of #14 wire between the appropriate
terminals.

73,

    ... Joe, W4TV


On 7/14/2011 10:40 AM, Dick Dievendorff wrote:

> This seems awfully expensive.
>
> Array Solutions doesn't spend that much for the relays inside their Six Pak.
>
> Top Ten devices doesn't spend that much for the SPDT relay inside their A/B
> station selector.  That unit goes for $77, and that includes a nice box and
> the connectors.
>
> The T/R switch within my Ameritron AL-1200 doesn't cost that much.
>
> Wouldn't a sealed or frame relay do the job?  600 watts into a 50 ohm
> resistive load is 12 Amps.  20A DPDT frame relays can be acquired for a lot
> less than a coaxial relay.
>
> SPST relays cost even less.  KK1L uses relays that are advertised at about
> $3.16 each in his 2 x 6 antenna switch.
>
> Is it necessary to operate concurrently on HF and 6 meters?  Wouldn't a
> couple of SPST relays suffice for this application?
>
> 100 watts into 50 ohms is 2A. You can use a much smaller relay on the 100
> watt exciter to amplifier side. I'd use 5A relay.
>
> 73 de Dick, K6KR
>
>
>> That can be accomplished with three DPDT coaxial relays such as the CX800M
> ($159/ea from http://www.rfparts.com/coaxial.html ) $477 total
>
>> It can be done with two coaxial transfer switches but probably cost more
> (KC 1420-820 from
> http://www.surplussales.com/Relays/rfcoaxialrelays/rfcoax_n.html
>
> are $275/ea. ($550 total)
>
> ______________________________________________________________
> 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
>

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[Edward R Cole]

First off I was replying to N8NFR's request for "info how to do
this".   Don't shoot the messenger!

The requirement for simultaneous connection to both antennas adds the
need for DPDT relays.  Of course a simpler set up could use simpler
relays.  I have not heard whether the KPA-500 has a bypass RF path
for running with just low-power.  All this has to be considered.  And
that is why such switching circuits properly belong outside the amp
or the tuner (I my opinion).

I would look very careful at all these after-market switching
boxes.  Check for RF current ratings (you will probably not find
any).  When loads are resistive math is simple - when SWR is high it
gets "strange" and many relays will fail.

I just burned up a 1200w rated coax relay that was running into <1.1
SWR load.  I was running 1200w!  The replacement is rated to
3kW.  Original relay was a CX600NL.  You get what you pay for.

Open frame relays are fine for 60-Hz AC and DC, but really are a
cheap way out for RF switching (beware).  Again may run fine at 100w
into resonant/matched antennas.  RF voltage really spikes when not
resonant.  This topic is around running the KPA-500 at 500w so be
careful about power ratings.

Most of my coax switching is manual rotary coax switches or I am just
connecting the coax manually.  Relays are remote on towers for the
most part and not used on HF.
---------------
Aside:
Simplest, most reliable, coax matrix has all the antennas terminated
to panel connectors on big plate panel.  Radios and amplifiers are
also terminated to connectors.  To connect any radio/amp/tuner to any
antenna one uses a coax jumper between the appropriate connectors -
no switches, no logic, KISS!

Of course this is slow so will not satisfy contesters, DXers and
anyone who is used to "push-the-button" electronics!
Ed - KL7UW
------------------------------

Message: 36
Date: Thu, 14 Jul 2011 07:40:57 -0700
From: "Dick Dievendorff" <[hidden email]>
Subject: Re: [Elecraft] KPA500 switching ideas with a Flex-5000A?
To: <[hidden email]>
Message-ID: <003201cc4234$0b696190$223c24b0$@comcast.net>
Content-Type: text/plain;       charset="us-ascii"

This seems awfully expensive.

Array Solutions doesn't spend that much for the relays inside their Six Pak.

Top Ten devices doesn't spend that much for the SPDT relay inside their A/B
station selector.  That unit goes for $77, and that includes a nice box and
the connectors.

The T/R switch within my Ameritron AL-1200 doesn't cost that much.

Wouldn't a sealed or frame relay do the job?  600 watts into a 50 ohm
resistive load is 12 Amps.  20A DPDT frame relays can be acquired for a lot
less than a coaxial relay.

SPST relays cost even less.  KK1L uses relays that are advertised at about
$3.16 each in his 2 x 6 antenna switch.

Is it necessary to operate concurrently on HF and 6 meters?  Wouldn't a
couple of SPST relays suffice for this application?

100 watts into 50 ohms is 2A. You can use a much smaller relay on the 100
watt exciter to amplifier side. I'd use 5A relay.

73 de Dick, K6KR

 > That can be accomplished with three DPDT coaxial relays such as the CX800M

($159/ea from http://www.rfparts.com/coaxial.html ) $477 total

 > It can be done with two coaxial transfer switches but probably cost more

(KC 1420-820 from
http://www.surplussales.com/Relays/rfcoaxialrelays/rfcoax_n.html

are $275/ea. ($550 total)






73, Ed - KL7UW, WD2XSH/45
======================================
BP40IQ   500 KHz - 10-GHz   www.kl7uw.com
EME: 50-1.1kw?, 144-1.4kw, 432-100w, 1296-60w, 3400-?
DUBUS Magazine USA Rep [hidden email]
======================================

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