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KX1 ATU causes power to drop off...

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ke9uw

KX1 ATU causes power to drop off...

I just finished the KX1 kit and without the tuner, power output into a 50 ohm load is about 10W on 80M, and 4W on 40M, 30M, and 20M using a Bird meter, 50W slug.
However the ATU which seems to work well in all testing, all the relays click, etc., in TUNE the power starts out at a reading of about 3 watts (40, 30, 20...a watt higher on 80) and falls off in about 2 to 3 seconds to about .5 watts. The Bird meter shows exactly the same power fall off.
Also the SWR reading in all cases reads 1.0 using the dummy load. So it seems like something is heating up (don't feel any heat anywhere) and the power falls off...but it still always reads an SWR of 1.0 when I go out of TUNE.
When I remove the ATU and install the jumper the power is steady for all bands (just higher on 80M).

When I activate L0 thru L3 and C1 thru C3, I get a significant change (normal) in SWR cycling thru L0 thru L3, but cycling thru C1 thru C3, the SWR seems to just change from 2.0 to 2.1 to 2.0

Not sure what to look at...

Chuck, KE9UW

ke9uw

Re: KX1 ATU causes power to drop off...

Oh and the ATU is in the CAL (bypass) mode. Of course it is in the TUN mode for the testing of inserting different L and C elements and noting SWR changes to see that all the elements are working.

Chuck, KE9UW

Don Wilhelm-4

Re: KX1 ATU causes power to drop off...

In reply to this post by ke9uw

Chuck,

Look at the Low Pass Filter.
The PA transistor cannot really go to 10 watts output - I suspect the
relay on the LPF board is not being activated on 80 meters and is
allowing a low of 2nd and 3rd harmonic energy get through. A 'scope
would show that, but for some reason or another, that makes the 80 meter
output look like 10 watts of power on a wattmeter.

Once you get the Low Pass Filter working correctly on all bands, try the
KXAT1 again and if the power falls off - I don't think that is a related
problem.

73,
Don W3FPR

On 6/4/2012 6:43 PM, ke9uw wrote:

> I just finished the KX1 kit and without the tuner, power output into a 50 ohm
> load is about 10W on 80M, and 4W on 40M, 30M, and 20M using a Bird meter,
> 50W slug.
> However the ATU which seems to work well in all testing, all the relays
> click, etc., in TUNE the power starts out at a reading of about 3 watts (40,
> 30, 20...a watt higher on 80) and falls off in about 2 to 3 seconds to about
> .5 watts. The Bird meter shows exactly the same power fall off.
> Also the SWR reading in all cases reads 1.0 using the dummy load. So it
> seems like something is heating up (don't feel any heat anywhere) and the
> power falls off...but it still always reads an SWR of 1.0 when I go out of
> TUNE.
> When I remove the ATU and install the jumper the power is steady for all
> bands (just higher on 80M).
>

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ke9uw

Re: KX1 ATU causes power to drop off...

In reply to this post by ke9uw

I bypassed the tuner relays, but makes no difference. I left the one turn link in ckt.
I thought maybe maybe the tuner being in place was affecting the drive rf into the output xistor,
but it looks like the same rf drive on the scope with the tuner in or out...but not the same output rf because the
rf into the tuner does just what the rf does on the output of the tuner...drifts down to a smaller level.
Baffled...

Chuck, KE9UW
aka Jack, BMW Motorcycles BMWMOA #224

________________________________________
From: [hidden email] [[hidden email]] on behalf of ke9uw [[hidden email]]
Sent: Monday, June 04, 2012 6:03 PM
To: [hidden email]
Subject: Re: [Elecraft] KX1 ATU causes power to drop off...

Oh and the ATU is in the CAL (bypass) mode. Of course it is in the TUN mode
for the testing of inserting different L and C elements and noting SWR
changes to see that all the elements are working.

-----
Chuck, KE9UW
--
View this message in context: http://elecraft.365791.n2.nabble.com/KX1-ATU-causes-power-to-drop-off-tp7557109p7557111.html
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Chuck, KE9UW

ke9uw

Re: KX1 ATU causes power to drop off...

In reply to this post by Don Wilhelm-4

Yes. E was not going low and F not turning on the relay.
The power out on 80M is 4 watts now. The other bands
are around 3.6 to 3.8 watts.
I still have the tuner in reduces the power out on
all bands and drops to less than a watt.
When I push on the LPF board, the power goes down...
and the ATU does that with a relay.
So that's my problem. I'll check why.
Thankyou so much, I would have been going in circles without
the LPF relay tip.

Chuck, KE9UW
aka Jack, BMW Motorcycles BMWMOA #224

________________________________________
From: Don Wilhelm [[hidden email]]
Sent: Monday, June 04, 2012 7:44 PM
To: hawley, charles j jr
Cc: [hidden email]
Subject: Re: [Elecraft] KX1 ATU causes power to drop off...

Chuck,

Look at the Low Pass Filter.
The PA transistor cannot really go to 10 watts output - I suspect the
relay on the LPF board is not being activated on 80 meters and is
allowing a low of 2nd and 3rd harmonic energy get through. A 'scope
would show that, but for some reason or another, that makes the 80 meter
output look like 10 watts of power on a wattmeter.

Once you get the Low Pass Filter working correctly on all bands, try the
KXAT1 again and if the power falls off - I don't think that is a related
problem.

73,
Don W3FPR

On 6/4/2012 6:43 PM, ke9uw wrote:

Chuck, KE9UW

Don Wilhelm-4

Re: KX1 ATU causes power to drop off...

Chuck,

That is progress, but for the life of me, I cannot think of any way the
KXAT1 would cause the power to gradually decrease. It is getting late
for me today, so I will sleep on it and see if anything pops into my
head in the morning.

One thought that does occur to me is that there may be a bad solder
connection somewhere in the KXAT1.

73,
Don W3FPR

On 6/4/2012 10:04 PM, hawley, charles j jr wrote:

> Yes. E was not going low and F not turning on the relay.
> The power out on 80M is 4 watts now. The other bands
> are around 3.6 to 3.8 watts.
> I still have the tuner in reduces the power out on
> all bands and drops to less than a watt.
> When I push on the LPF board, the power goes down...
> and the ATU does that with a relay.
> So that's my problem. I'll check why.
> Thankyou so much, I would have been going in circles without
> the LPF relay tip.
>
> Chuck, KE9UW
> aka Jack, BMW Motorcycles BMWMOA #224
>
> ________________________________________
> From: Don Wilhelm [[hidden email]]
> Sent: Monday, June 04, 2012 7:44 PM
> To: hawley, charles j jr
> Cc: [hidden email]
> Subject: Re: [Elecraft] KX1 ATU causes power to drop off...
>
> Chuck,
>
> Look at the Low Pass Filter.
> The PA transistor cannot really go to 10 watts output - I suspect the
> relay on the LPF board is not being activated on 80 meters and is
> allowing a low of 2nd and 3rd harmonic energy get through. A 'scope
> would show that, but for some reason or another, that makes the 80 meter
> output look like 10 watts of power on a wattmeter.
>
> Once you get the Low Pass Filter working correctly on all bands, try the
> KXAT1 again and if the power falls off - I don't think that is a related
> problem.
>
> 73,
> Don W3FPR
>
> On 6/4/2012 6:43 PM, ke9uw wrote:
>> I just finished the KX1 kit and without the tuner, power output into a 50 ohm
>> load is about 10W on 80M, and 4W on 40M, 30M, and 20M using a Bird meter,
>> 50W slug.
>> However the ATU which seems to work well in all testing, all the relays
>> click, etc., in TUNE the power starts out at a reading of about 3 watts (40,
>> 30, 20...a watt higher on 80) and falls off in about 2 to 3 seconds to about
>> .5 watts. The Bird meter shows exactly the same power fall off.
>> Also the SWR reading in all cases reads 1.0 using the dummy load. So it
>> seems like something is heating up (don't feel any heat anywhere) and the
>> power falls off...but it still always reads an SWR of 1.0 when I go out of
>> TUNE.
>> When I remove the ATU and install the jumper the power is steady for all
>> bands (just higher on 80M).
>>
> ______________________________________________________________
> 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
>

ke9uw

Re: KX1 ATU causes power to drop off...

Fixed.
It was a solder connection on the low pass filter board. When the ATU
pushed a bit on the LPF board, the power took a dip.
I re-soldered the two 2-3 junctions on the LPF.
The power is constant now, about 3.6 or so on 7 thru 14
and about 4.1 on 80M with the tuner in or out.
It was all in the LPF board...both issues. I was really
careful with that part...but not careful enough :)
Thanks again.

Chuck, KE9UW
aka Jack, BMW Motorcycles BMWMOA #224

________________________________________
From: Don Wilhelm [[hidden email]]
Sent: Monday, June 04, 2012 9:19 PM
To: hawley, charles j jr
Cc: [hidden email]
Subject: Re: [Elecraft] KX1 ATU causes power to drop off...

Chuck,

That is progress, but for the life of me, I cannot think of any way the
KXAT1 would cause the power to gradually decrease. It is getting late
for me today, so I will sleep on it and see if anything pops into my
head in the morning.

One thought that does occur to me is that there may be a bad solder
connection somewhere in the KXAT1.

73,
Don W3FPR

On 6/4/2012 10:04 PM, hawley, charles j jr wrote:

Chuck, KE9UW

Don Wilhelm-4

Re: KX1 ATU causes power to drop off...

Chuck,

That LPF is the most common downfall of the KXB3080 installation. It is
small and quite compact, and does require a lot of careful work.

I am glad to hear your KX1 is now working OK.

73,
Don W3FPR

On 6/4/2012 10:48 PM, hawley, charles j jr wrote:

> Fixed.
> It was a solder connection on the low pass filter board. When the ATU
> pushed a bit on the LPF board, the power took a dip.
> I re-soldered the two 2-3 junctions on the LPF.
> The power is constant now, about 3.6 or so on 7 thru 14
> and about 4.1 on 80M with the tuner in or out.
> It was all in the LPF board...both issues. I was really
> careful with that part...but not careful enough :)
> Thanks again.
>