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[K2] SWR meter reads 'funny' on just 20 meters

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inventor61 .

[K2] SWR meter reads 'funny' on just 20 meters

Don (and list)

I just replaced my 'back up shack' antenna today (it was a 45/90 OCF
experiment) with a 138' open wire fed doublet. The center is up 50' and
the elements are more-or-less installed. They will get more installed
later.

I used the 'Ladder-Snap' pieces to make the feedline. In 35 years of being
licensed and active, I have never had an open wire fed antenna. They look
cool, kinda retro, sort of old (like me, I am 53 today), a real classic.

Anyway, I fired up the old K2 and hooded it up to the new aerial. The K2
(the same one since 1999) has the KAT2 installed, which works well, but the
ATU portion isn't in line for this setup. Instead, I have a
DC-phantom-powered SGC-239 out at the feedpoint.

Inside, I have an A-B switch that can steer the rig's output to a lab grade
50 ohm load.

On all bands but 20 meters, the outside tuner quickly found a 'solution'
for the new doublet, none worse a match that 1.5:1. Nice. However, on 20,
the K2 said it was 3.0:1 ...

Hmm..

I flipped to the dummy load. All bands show 1:1 on the K2 display except
for 20, where it reads 1.8:1 ... into 50 ohms.

I switched the K2 display to read FWD & REV, instead of SWR, and then the
display showed 5.7W fwd and 0.7W reverse into the dummy load.

So, what do you think the problem might be?

Thanks in advance for the opinion. Hope you're enjoying the terrific
weather.

Steve KZ1X
Chapel Hill
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Phil Wheeler-2

Re: [K2] SWR meter reads 'funny' on just 20 meters

Not an Elecraft ATU? Well, there's the problem :-)

More seriously, perhaps your tuner does not like
what it is seeing.

73, Phil w7ox

On 5/6/14, 6:21 PM, inventor61 . wrote:

> Don (and list)
>
>
> I just replaced my 'back up shack' antenna today (it was a 45/90 OCF
> experiment) with a 138' open wire fed doublet. The center is up 50' and
> the elements are more-or-less installed. They will get more installed
> later.
>
> I used the 'Ladder-Snap' pieces to make the feedline. In 35 years of being
> licensed and active, I have never had an open wire fed antenna. They look
> cool, kinda retro, sort of old (like me, I am 53 today), a real classic.
>
> Anyway, I fired up the old K2 and hooded it up to the new aerial. The K2
> (the same one since 1999) has the KAT2 installed, which works well, but the
> ATU portion isn't in line for this setup. Instead, I have a
> DC-phantom-powered SGC-239 out at the feedpoint.
>
> Inside, I have an A-B switch that can steer the rig's output to a lab grade
> 50 ohm load.
>
> On all bands but 20 meters, the outside tuner quickly found a 'solution'
> for the new doublet, none worse a match that 1.5:1. Nice. However, on 20,
> the K2 said it was 3.0:1 ...
>
> Hmm..
>
> I flipped to the dummy load. All bands show 1:1 on the K2 display except
> for 20, where it reads 1.8:1 ... into 50 ohms.
>
> I switched the K2 display to read FWD & REV, instead of SWR, and then the
> display showed 5.7W fwd and 0.7W reverse into the dummy load.
>
> So, what do you think the problem might be?
>
> Thanks in advance for the opinion. Hope you're enjoying the terrific
> weather.
>
>
> Steve KZ1X
> Chapel Hill

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Vic Rosenthal

Re: [K2] SWR meter reads 'funny' on just 20 meters

Well, I see how his dipole might be presenting an extreme value of
impedance on 20, depending on the length and impedance of the line.

But why is his dummy load weird only on 20M? That's a puzzle -- and it
needs to be solved first.

On 5/6/2014 6:31 PM, Phil Wheeler wrote:

> Not an Elecraft ATU? Well, there's the problem :-)
>
> More seriously, perhaps your tuner does not like what it is seeing.
>
> 73, Phil w7ox
>
>
> On 5/6/14, 6:21 PM, inventor61 . wrote:
>> Don (and list)
>>
>>
>> I just replaced my 'back up shack' antenna today (it was a 45/90 OCF
>> experiment) with a 138' open wire fed doublet. The center is up 50' and
>> the elements are more-or-less installed. They will get more installed
>> later.
>>
>> I used the 'Ladder-Snap' pieces to make the feedline. In 35 years of
>> being
>> licensed and active, I have never had an open wire fed antenna. They
>> look
>> cool, kinda retro, sort of old (like me, I am 53 today), a real classic.
>>
>> Anyway, I fired up the old K2 and hooded it up to the new aerial. The K2
>> (the same one since 1999) has the KAT2 installed, which works well,
>> but the
>> ATU portion isn't in line for this setup. Instead, I have a
>> DC-phantom-powered SGC-239 out at the feedpoint.
>>
>> Inside, I have an A-B switch that can steer the rig's output to a lab
>> grade
>> 50 ohm load.
>>
>> On all bands but 20 meters, the outside tuner quickly found a 'solution'
>> for the new doublet, none worse a match that 1.5:1. Nice. However,
>> on 20,
>> the K2 said it was 3.0:1 ...
>>
>> Hmm..
>>
>> I flipped to the dummy load. All bands show 1:1 on the K2 display except
>> for 20, where it reads 1.8:1 ... into 50 ohms.
>>
>> I switched the K2 display to read FWD & REV, instead of SWR, and then the
>> display showed 5.7W fwd and 0.7W reverse into the dummy load.
>>
>> So, what do you think the problem might be?
>>
>> Thanks in advance for the opinion. Hope you're enjoying the terrific
>> weather.
>>
>>
>> Steve KZ1X
>> Chapel Hill

--
73,
Vic, K2VCO
Fresno CA
http://www.qsl.net/k2vco/

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Phil Wheeler-2

Re: [K2] SWR meter reads 'funny' on just 20 meters

In reply to this post by inventor61 .

It sounds like something may be amiss in the K2
for 20m; not sure how or what. But it may be the
SGC is getting to 1.5:1 on 20 also -- since the K2
seems to be reading 1.8:1 for a dummy load which
is 1.0:1 we can assume.

Do you have another rig you can test this with --
or maybe a meter you can place at the output of
the K2 as a redundant measure of SWR or forward
and reflected power?

Phil w7ox

On 5/6/14, 6:21 PM, inventor61 . wrote:

Don Wilhelm-4

Re: [K2] SWR meter reads 'funny' on just 20 meters

In reply to this post by inventor61 .

Steve,

Yes, the weather has been great here in the Triangle area.

Generally OCF dipoles can generate a lot of common mode RF and bring it
into the shack unless measures are taken to kill that aspect.
However, your results on 20 meters with the dummy load do deserve a lot
of careful consideration.

First a statement that the KAT2 is not band dependent when in CAL P or
CAL S ATU menu state.
The response of the KAT2 diodes may vary a bit with frequency, but not
to the extent you have stated, and certainly not on any one band.

You say the KAT2 is not "in line". The menu ATU settings that take the
KAT2 "off line" are CAL n, CAL P and CAL S. If you were using CAL P,
the L and C solution for 20 meters was still present, but the display
during a TUNE would show the power output with that tuning solution present.

I would suggest that you continue to test into the dummy load, and set
the KAT2 to Auto, then do a TUNE on 20 meters to see if anything changes.

If things remain the same, I would suspect that there is a relay in the
KAT2 that is not working properly and leaving some residual L or C in
the circuit. Normally, that would affect all bands, but there is an off
chance that it would only be noticed on one band. The relays for the
capacitors are relatively easy to check - go to CAL P or CAL S in the
ATU menu and then check the resistance to ground for both legs of the
capacitor - all should measure infinite resistance.

Checking the inductors is not as easy (unless you measure the inductance
from input to output of the KAT2 with an inductance meter). The normal
procedure is to lift one end of each of the inductors and make certain
that there is still continuity from the input center conductor to the
output center conductor. If that continuity test fails, find the relay
that is open and once found determine why it is not operating to short
out the inductor.

OK, so much for that kind of theory stuff. Let's simplify a bit.
If you have excessive L or C in the KAT2, the wattmeter bridge will not
balance. So the first quick check is to set the ATU menu to CAL n and
check the wattmeter for a good null on C55.
If you do achieve a good null, then do the CAL P and CAL S calibration
and check the SWR indication on all bands again.

If you cannot achieve a good null, it could be that something has
changed in the wattmeter section, or (as above) it could be a stuck
relay). To check whether it is a wattmeter problem or an L/C or relay
problem, set to ANT1, and then separate the KAT2 LC board from the
Control Board, then put a long jumper between J4 pin 2 and J5 pin 15
(one pin in from the ends of those two headers).
Again try the null procedure and the calibration. If all is OK with
that test, the problem is on the L/C board, but if you still cannot
achieve a good null, blame the wattmeter components.
Should it be the wattmeter at fault, any of the components C54, C55, R3,
R4, D1 and D2 are suspect.
First check the diodes with an ohmmeter preferably set for diode test.
If OK, proceed to the capacitors - replacement is most certain test
because they may behave differently at RF than at the low test frequency
used in a capacitance meter like the AADE. For the resistors, check the
soldering first. If you have to measure the values, lift one end to
make the measurement.

Good luck with it.

Lastly Steve, if you are using your garage mounted high power dummy
load, I suggest that you use another dummy load at the workbench (or
shack) with a short length of coax as a check. There is a possibility
that the particular length of coax has somehow changed characteristics
(maybe loose connectors) and is causing problems on 20 meters due to its
length.

That exhausts all my current suggestions.

73,
Don W3FPR

On 5/6/2014 9:21 PM, inventor61 . wrote:

> Don (and list)
>
>
> I just replaced my 'back up shack' antenna today (it was a 45/90 OCF
> experiment) with a 138' open wire fed doublet. The center is up 50'
> and the elements are more-or-less installed. They will get more
> installed later.
>
> I used the 'Ladder-Snap' pieces to make the feedline. In 35 years of
> being licensed and active, I have never had an open wire fed antenna.
> They look cool, kinda retro, sort of old (like me, I am 53 today), a
> real classic.
>
> Anyway, I fired up the old K2 and hooded it up to the new aerial. The
> K2 (the same one since 1999) has the KAT2 installed, which works well,
> but the ATU portion isn't in line for this setup. Instead, I have a
> DC-phantom-powered SGC-239 out at the feedpoint.
>
> Inside, I have an A-B switch that can steer the rig's output to a lab
> grade 50 ohm load.
>
> On all bands but 20 meters, the outside tuner quickly found a
> 'solution' for the new doublet, none worse a match that 1.5:1. Nice.
> However, on 20, the K2 said it was 3.0:1 ...
>
> Hmm..
>
> I flipped to the dummy load. All bands show 1:1 on the K2 display
> except for 20, where it reads 1.8:1 ... into 50 ohms.
>
> I switched the K2 display to read FWD & REV, instead of SWR, and then
> the display showed 5.7W fwd and 0.7W reverse into the dummy load.
>
> So, what do you think the problem might be?
>
> Thanks in advance for the opinion. Hope you're enjoying the terrific
> weather.
>
>
> Steve KZ1X
> Chapel Hill

Don Wilhelm-4

Re: [K2] SWR meter reads 'funny' on just 20 meters

In reply to this post by inventor61 .

In the sentence below: Replace "CAL P" with "CAL PWR" to be correct.

73,
Don W3FPR
------------------------------------------------------------------------------

If you were using CAL P, the L and C solution for 20 meters was still
present, but the display during a TUNE would show the power output with
that tuning solution present.
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Re: [K3] Lose SUB rx audio with N1MM "tilde"

In reply to this post by Don Wilhelm-4

Probably an issue to ask N1MM guys but ..

N1MM has a function using the "tilde" key to turn the SUB rx on and off. I
normally only use this function when split to listen to the pileup.

It seems to work fine for a few changes , then the next time , the sub rx
will obviously be activated because the main rx sigs drop the normal 3 dB
but there is no sub rx audio. A power off / on always returns the function
for awhile . Unfortunately if I do a power off/on , I lose the split and if
I FORGET
that happens in the heat of the battle , I become an instant lid.

I have settings:
AFX BIN
SPKRS 1
SPKR+PH NO
AF GAIN LO
L-MIX-R Ab-Ab

Am I missing something ?

Hank K7HP

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