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low power on 6 meters

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bobgarceau

low power on 6 meters

I have seen this issue posted before, but no answers that I can see.

I have a K3 and the output is no more than 52 watts with an swr of
1.23..sometime get it up to 62.

Now I have the KPA500 and using 40 watts to exite the amp, I get just a tad
over 425 watts.

Don't think I want to push it over 40 watts. And to be honest there probably
isn't much difference between 425 and 500, but would like to know why I
can't get the 100 like I should..

Bob, W1EQ

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Re: low power on 6 meters

Bob, do you have an amplifier in line on 6 meters? I have noticed that my
Clipperton L absorbs about 15 watts on 6 meters even when it it turned off. It
does not do this on the lower bands. You can easily find out by taking the
connectors loose on the amp and replacing with a short barrel connector. May
not be your problem, but it is mine.
Willis 'Cookie' Cooke
K5EWJ & Trustee N5BPS, USS Cavalla, USS Stewart

________________________________
From: Robert Garceau <[hidden email]>
To: Elecraft <[hidden email]>
Sent: Sun, July 17, 2011 6:11:59 AM
Subject: [Elecraft] low power on 6 meters

I have seen this issue posted before, but no answers that I can see.

I have a K3 and the output is no more than 52 watts with an swr of
1.23..sometime get it up to 62.

Now I have the KPA500 and using 40 watts to exite the amp, I get just a tad
over 425 watts.

Don't think I want to push it over 40 watts. And to be honest there probably
isn't much difference between 425 and 500, but would like to know why I
can't get the 100 like I should..

Bob, W1EQ

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Buck - k4ia

Re: low power on 6 meters

I notice high swr when my AL572 is in the antenna circuit - even when turned off. When I hook the coax directly to the K3, the swr is 1:1. Haven't figured out why except maybe there is a low pass filter built in the amp that is in line all the time.

Craig Buck

On Jul 17, 2011, at 11:07 AM, WILLIS COOKE <[hidden email]> wrote:

> Bob, do you have an amplifier in line on 6 meters? I have noticed that my
> Clipperton L absorbs about 15 watts on 6 meters even when it it turned off. It
> does not do this on the lower bands. You can easily find out by taking the
> connectors loose on the amp and replacing with a short barrel connector. May
> not be your problem, but it is mine.
> Willis 'Cookie' Cooke
> K5EWJ & Trustee N5BPS, USS Cavalla, USS Stewart
>
>
>
>
> ________________________________
> From: Robert Garceau <[hidden email]>
> To: Elecraft <[hidden email]>
> Sent: Sun, July 17, 2011 6:11:59 AM
> Subject: [Elecraft] low power on 6 meters
>
> I have seen this issue posted before, but no answers that I can see.
>
>
>
> I have a K3 and the output is no more than 52 watts with an swr of
> 1.23..sometime get it up to 62.
>
>
>
> Now I have the KPA500 and using 40 watts to exite the amp, I get just a tad
> over 425 watts.
>
>
>
> Don't think I want to push it over 40 watts. And to be honest there probably
> isn't much difference between 425 and 500, but would like to know why I
> can't get the 100 like I should..
>
>
>
> Bob, W1EQ
>
>
>
> ______________________________________________________________
> 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
> ______________________________________________________________
> 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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Re: low power on 6 meters

The input circuit is bypassed by the relay so the only thing in the path is the
relay, coax connectors and the wires. I think it is the wires. I have no such
difficulty on 10 meters. My amp is the Dentron Clipperton L with the AD5X QSK
mod. The connecting wires are about 2.5 inches long. The QSK mod works great
on low bands when the amp is on. The relay noise is less than the fan noise and
it has survived several thousand QSOs with no problem other than 6 meters. The
Dentron is the predecessor to the AL572 with the same tube lineup and a bit more
compact layout.
Willis 'Cookie' Cooke
K5EWJ & Trustee N5BPS, USS Cavalla, USS Stewart

________________________________
From: K4ia <[hidden email]>
To: WILLIS COOKE <[hidden email]>
Cc: Elecraft Reflector <[hidden email]>
Sent: Sun, July 17, 2011 10:35:19 AM
Subject: Re: [Elecraft] low power on 6 meters

I notice high swr when my AL572 is in the antenna circuit - even when turned
off. When I hook the coax directly to the K3, the swr is 1:1. Haven't figured
out why except maybe there is a low pass filter built in the amp that is in line
all the time.

Craig Buck

On Jul 17, 2011, at 11:07 AM, WILLIS COOKE <[hidden email]> wrote:

> Bob, do you have an amplifier in line on 6 meters? I have noticed that my
> Clipperton L absorbs about 15 watts on 6 meters even when it it turned off. It
>
> does not do this on the lower bands. You can easily find out by taking the
> connectors loose on the amp and replacing with a short barrel connector. May
> not be your problem, but it is mine.
> Willis 'Cookie' Cooke
> K5EWJ & Trustee N5BPS, USS Cavalla, USS Stewart
>
>
>
>
> ________________________________
> From: Robert Garceau <[hidden email]>
> To: Elecraft <[hidden email]>
> Sent: Sun, July 17, 2011 6:11:59 AM
> Subject: [Elecraft] low power on 6 meters
>
> I have seen this issue posted before, but no answers that I can see.
>
>
>
> I have a K3 and the output is no more than 52 watts with an swr of
> 1.23..sometime get it up to 62.
>
>
>
> Now I have the KPA500 and using 40 watts to exite the amp, I get just a tad
> over 425 watts.
>
>
>
> Don't think I want to push it over 40 watts. And to be honest there probably
> isn't much difference between 425 and 500, but would like to know why I
> can't get the 100 like I should..
>
>
>
> Bob, W1EQ
>
>
>
> ______________________________________________________________
> 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
> ______________________________________________________________
> 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

Joe Subich, W4TV-4

Re: low power on 6 meters

In reply to this post by Buck - k4ia

> I notice high swr when my AL572 is in the antenna circuit - even
> when turned off. When I hook the coax directly to the K3, the swr
> is 1:1. Haven't figured out why except maybe there is a low pass
> filter built in the amp that is in line all the time.

Many of these amplifiers use open frame relays and long connecting
wires for the T/R (bypass) switching function. The inductance of
the wires/long relay contacts causes a significant impedance bump
on six meters (and to a lesser extent on 10 meters).

If you want to to resolve the problem connect a small capacitor from
the "bypass wire" (the connection between the two normally closed
relay contacts) to ground/chassis. You will need to experiment -
or use a trimmer - the capacitor value will be small, typically less
than 10 pF.

73,

... Joe, W4TV

On 7/17/2011 11:35 AM, K4ia wrote:

> I notice high swr when my AL572 is in the antenna circuit - even when turned off. When I hook the coax directly to the K3, the swr is 1:1. Haven't figured out why except maybe there is a low pass filter built in the amp that is in line all the time.
>
> Craig Buck
>
> On Jul 17, 2011, at 11:07 AM, WILLIS COOKE<[hidden email]> wrote:
>
>> Bob, do you have an amplifier in line on 6 meters? I have noticed that my
>> Clipperton L absorbs about 15 watts on 6 meters even when it it turned off. It
>> does not do this on the lower bands. You can easily find out by taking the
>> connectors loose on the amp and replacing with a short barrel connector. May
>> not be your problem, but it is mine.
>> Willis 'Cookie' Cooke
>> K5EWJ& Trustee N5BPS, USS Cavalla, USS Stewart
>>
>>
>>
>>
>> ________________________________
>> From: Robert Garceau<[hidden email]>
>> To: Elecraft<[hidden email]>
>> Sent: Sun, July 17, 2011 6:11:59 AM
>> Subject: [Elecraft] low power on 6 meters
>>
>> I have seen this issue posted before, but no answers that I can see.
>>
>>
>>
>> I have a K3 and the output is no more than 52 watts with an swr of
>> 1.23..sometime get it up to 62.
>>
>>
>>
>> Now I have the KPA500 and using 40 watts to exite the amp, I get just a tad
>> over 425 watts.
>>
>>
>>
>> Don't think I want to push it over 40 watts. And to be honest there probably
>> isn't much difference between 425 and 500, but would like to know why I
>> can't get the 100 like I should..
>>
>>
>>
>> Bob, W1EQ
>>
>>
>>
>> ______________________________________________________________
>> 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
>> ______________________________________________________________
>> 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
> ______________________________________________________________
> 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
>

Edward R Cole

Re: low power on 6 meters

In reply to this post by bobgarceau

Willis writes: "The input circuit is bypassed by the relay so the
only thing in the?path is the
relay, coax connectors?and the wires.? I think it is the wires.?"

Craig Buck writes: "I notice high swr when my AL572 is in the antenna
circuit - even when turned
off.? When I hook the coax directly to the K3, the swr is 1:1. Haven't figured
out why except maybe there is a low pass filter built in the amp that
is in line
all the time.?"

I would ask if the relays inside the amps are coaxial relays or
open-frame dc relays? I have seen that very common use in HF
amps. So it works up to 30-MHz but SWR is high on 50-MHz. Well
perhaps you have heard the VHFers refer to HF as the "dc
bands"? Manufacturers try to "cheap-out" by using dc relays that are
not constant impedance and that works OK on HF, for the most
part. But when wavelength becomes shorter so that physical
dimensions of relays and "wires" become elements of transmission
lines they are no longer 50-ohm impedance. This IS why VHFers use
high-quality coaxial relays in their home-built amplifiers with
bypass lines of RG-58 or even RG-8.

Look inside and see if the relays are "good ole dc relays"? I have a
Mirage A1015G 150w 6m amp and guess what the impedance is when in
bypass? SWR=1.4 even when I have a 50-ohm termination connected to
the output of the amplifier. Connect the termination directly to the
coax line that connects K3 to Mirage and SWR=1.0 Fortunately, I have
an antenna tuner for 160-6m and I tweak out the mismatch when Mirage
is off-line. Input to the Mirage when on-line is 1.5 so I tune the
input using the antenna tuner. The antenna SWR= 1.06 so the Mirage
is happy without need of the tuner.

Suspect those relays! If the bypass is simple buss wire that too
will not match well at VHF.

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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Re: low power on 6 meters

The relays in most amps are open frame and definitely not designed for six
meters. Mine is an aftermarket kit designed for an AL600 and modified by me to
work on a boat anchor Dentron Clipperton L amplifier. I am just offering a
suggestion about what might be causing the problem, not looking for a solution
from someone. The elegant solution is to buy a KPA-500 that is designed to go
with the K3 instead of using a Boat Anchor designed to work with a TS-520 or an
FT-101. The easy solution is to turn on the KAT-3 or to not look at the SWR on
the K3. The other solution is to disconnect the coax from the AMP and put in a
barrel connector. As for me, I have another 500 buro QSLs to answer today, so I
must be getting out.
Willis 'Cookie' Cooke
K5EWJ & Trustee N5BPS, USS Cavalla, USS Stewart

________________________________
From: Edward R. Cole <[hidden email]>
To: [hidden email]
Sent: Sun, July 17, 2011 12:36:48 PM
Subject: Re: [Elecraft] low power on 6 meters

Willis writes: "The input circuit is bypassed by the relay so the
only thing in the?path is the
relay, coax connectors?and the wires.? I think it is the wires.?"

Craig Buck writes: "I notice high swr when my AL572 is in the antenna
circuit - even when turned
off.? When I hook the coax directly to the K3, the swr is 1:1. Haven't figured
out why except maybe there is a low pass filter built in the amp that
is in line
all the time.?"

I would ask if the relays inside the amps are coaxial relays or
open-frame dc relays? I have seen that very common use in HF
amps. So it works up to 30-MHz but SWR is high on 50-MHz. Well
perhaps you have heard the VHFers refer to HF as the "dc
bands"? Manufacturers try to "cheap-out" by using dc relays that are
not constant impedance and that works OK on HF, for the most
part. But when wavelength becomes shorter so that physical
dimensions of relays and "wires" become elements of transmission
lines they are no longer 50-ohm impedance. This IS why VHFers use
high-quality coaxial relays in their home-built amplifiers with
bypass lines of RG-58 or even RG-8.

Look inside and see if the relays are "good ole dc relays"? I have a
Mirage A1015G 150w 6m amp and guess what the impedance is when in
bypass? SWR=1.4 even when I have a 50-ohm termination connected to
the output of the amplifier. Connect the termination directly to the
coax line that connects K3 to Mirage and SWR=1.0 Fortunately, I have
an antenna tuner for 160-6m and I tweak out the mismatch when Mirage
is off-line. Input to the Mirage when on-line is 1.5 so I tune the
input using the antenna tuner. The antenna SWR= 1.06 so the Mirage
is happy without need of the tuner.

Suspect those relays! If the bypass is simple buss wire that too
will not match well at VHF.

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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Robert Dorchuck

Re: low power on 6 meters

In reply to this post by bobgarceau

Hello Bob,
I did not see anything on the reflector that answered your question.
You should be able to get the full 100 watts out of the K3 on six
meters
without any problem. Have you done the TX gain calibration? In any
case
I would call support and see what they say.

I get over 100 watts out and this is through an old Alpha 78 amp (not
on) to
either the dummy load or the antenna.

Good luck.

Bob W6VY

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