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K2 Power Problem

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Larry Christensen

K2 Power Problem

I was working on my new K2 Alignment and Test Part III
All was going well until I got to the 40 Meter TX Alignment page 78
I followed the instructions but when I got to the "put K2 into TUNE
mode to peak the L1 I had not RF out. the display showed P.01 not the
P2.0
I was expected.
I tested and checked and could not find the problem. So I tried
another band.
This is what I found with the power out set to P 2.0
80M P 2.0
40M P .01
30M P 2.3
20M P .01
17M P 2.2
15M P 2.0
12M P .01
10M P .01

I have 4 bands with RF out and 4 band that do not.
I am missing the common connection in the 4 bad bands and what to
check next or what the problem could e.
I have check the obvious but I am missing something.
I have got through the reflector archives and have not found any
posting with this problem

Thanks in advance for any help

Larry
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Don Wilhelm-4

Re: K2 Power Problem

Larry,

I suggest your first step is to count the turns on all the toroids in
the Low Pass filter area.
Count the number of times the wire passes through the center of the core.
One extra turn would lower the cutoff frequency of the low pass filter.
Since many bands are arranged in pairs - 40 and 60 meters are paired, 30
and 20 are paired, 17 and 15 are paired and 12 and 10 meters are
paired. It looks like the higher band of each pair is giving you
problems. Since 12 and 10 meters are close in frequency, the cutoff may
have dropped below the 12 meter point.

Again, check the number of turns on the toroids as a first step.

73,
Don W3FPR

Larry Christensen wrote:

> I was working on my new K2 Alignment and Test Part III
> All was going well until I got to the 40 Meter TX Alignment page 78
> I followed the instructions but when I got to the "put K2 into TUNE
> mode to peak the L1 I had not RF out. the display showed P.01 not the
> P2.0
> I was expected.
> I tested and checked and could not find the problem. So I tried
> another band.
> This is what I found with the power out set to P 2.0
> 80M P 2.0
> 40M P .01
> 30M P 2.3
> 20M P .01
> 17M P 2.2
> 15M P 2.0
> 12M P .01
> 10M P .01
>
> I have 4 bands with RF out and 4 band that do not.
> I am missing the common connection in the 4 bad bands and what to
> check next or what the problem could e.
> I have check the obvious but I am missing something.
> I have got through the reflector archives and have not found any
> posting with this problem
>
> Thanks in advance for any help
>
>

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Post to: [hidden email]
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Larry Christensen

Re: K2 Power Problem

This post was updated on .

<quote author="Don Wilhelm">
Larry,

I suggest your first step is to count the turns on all the toroids in
the Low Pass filter area.
Count the number of times the wire passes through the center of the core.
One extra turn would lower the cutoff frequency of the low pass filter.
Since many bands are arranged in pairs - 40 and 60 meters are paired, 30
and 20 are paired, 17 and 15 are paired and 12 and 10 meters are
paired. It looks like the higher band of each pair is giving you
problems. Since 12 and 10 meters are close in frequency, the cutoff may
have dropped below the 12 meter point.

Again, check the number of turns on the toroids as a first step.

73,
Don W3FPR

Don

I checked and recheck the counts on the toroids all are correct.
I also removed the covers and rechecked the soldier joints all look good
I tested the toroid pads with a DMM all resistance readings are good.

I have check all the caps in the Low Pass Filter to insure they are correct.

Larry Christensen

Re: K2 Power Problem

Don Wilhelm wrote

Larry,

I suggest your first step is to count the turns on all the toroids in
the Low Pass filter area.
Count the number of times the wire passes through the center of the core.
One extra turn would lower the cutoff frequency of the low pass filter.
Since many bands are arranged in pairs - 40 and 60 meters are paired, 30
and 20 are paired, 17 and 15 are paired and 12 and 10 meters are
paired. It looks like the higher band of each pair is giving you
problems. Since 12 and 10 meters are close in frequency, the cutoff may
have dropped below the 12 meter point.

Again, check the number of turns on the toroids as a first step.

73,
Don W3FPR

Don

I checked and recheck the counts on the toroids all are correct.
I also removed the covers and rechecked the soldier joints all look good
I tested the toroid pads with a DMM all resistance readings are good.

I have check all the caps in the Low Pass Filter to insure they are correct.

I peaked the L1 L2 using the XG2 Receiver Test Oscillator. The rec. volume was very light so I
I continuned to test, using the Elecraft N-Gen the reciever this is what I found.
80M loud
40M very light
30M loud
20M slightly less than 80/30 but more than 40
18M same as 20M
15M same as 20M
12M very light
10M very light

(I have to get the parts and build the signal gen in the manual) before I can go on with the trace. All are with in limits until I got the the LPF/BPF & TR and Mixer IF Amp, and Crystals but I think that some decrease maybe due to not enough signal strenght from the N-Gen..

Larry Christensen

Re: K2 Power Problem

I GOT IT..
I checked all the components in both the BPF and the LPF all are correct peaked the vari. ind. in the BPF .
I re-read the instructions on the C6 cap on the bottom of the board.
I mistook the instructions (use the outer two holes) to mean use the two pads nearest the side (outboard) not the pad (1 & 3) as I should have.

On to the next step..

Thanks Gary and Don for your thoughts and suggestions.

Don Wilhelm-4

Re: K2 Power Problem

In reply to this post by Larry Christensen

Larry,

It is difficult to judge what the output should be with the N-gen -
there are just too many variables to draw any valid conclusions from
that information.

I suggest that you back up a bit and align the bandpass filters in
transmit at a power level of 1 to 2 watts. Use the band order specified
in the manual.

Once you have done that, check the maximum transmit power available on
all bands. If any bands are low AND draw excessive current, then check
the low pass filter for that band.

Once you have good output power on all bands, then you can evaluate the
receive knowing that the bandpass and the lowpass filters are OK. (Do
NOT readjust the bandpass - the transmit peaking is the final adjustment
and if it is peaked for transmit, it will also be peaked for the receive
condition).
I know this is a bit 'backwards' from the manual, but at the point where
you are stuck, this is the best path forward.

73,
Don W3FPR

Larry KA0PLW wrote:

>
>
> I have continuned to test, using the Elecraft N-Gen the reciever
> 80M loud
> 40M very light
> 30M loud
> 20M slightly less than 80/30 but more than 40
> 18M same as 20M
> 15M same as 20M
> 12M very light
> 10M very light
>
> (I have to get the parts and build the signal gen in the manual) before I
> can go on with the trace. All are with in limits until I got the the LPF/BPF
> & TR and Mixer IF Amp, and Crystals but I think that some decrease maybe due
> to not enough signal strenght from the N-Gen..
>
>
> -----
> Larry KA0PLW
> K1 2530
> K2 work in process
>
>