Elecraft

Help with troubleshooting K2 receiver?

Classic

List

Threaded

4 messages Options

WA7SPY

Help with troubleshooting K2 receiver?

I have my K2 built to the second alignment step. It passed all the tests
on the first part of the build on initial power up. My K2 is not hearing
the 7.0000 birdie. I am not hearing anything on 40 meters from receive
signals with an outside antenna connected or my broad band generator
connected to the antenna connector. The PLL linearization worked fine
with no errors and the end message showed up when it was finished.

I do hear the signal at J15 C6 on the left side as viewed looking down
from the top of my K2. I get a small signal increase when I inject my
broadband signal generator to the top of the case of Q21. I get an
increase in signal on pins 3 and 4 of the K1 relay. No increase on any
other pins when the 40 meter band is selected. I get a signal increase
at jumper W5 and W2. I get a small increase at W1. I get a small
increase on both sides of D6 diode. I get an increase at the case of
Q22. I have tripled checked component orientation and values, cold
solder joints.

I am able to get the pre amp and attenuator to work when I inject the
signal at W5. I am able to get all the freq readings on the BFO and
filters adjust fine. The cans for L1 and L2 have the big slots no marks.
I had to adjust them bottomed out and then got a slight signal increase.
It is almost as if the cans a for L1 and L2 are not the proper value. I
was only able to get 5.5 volts out of L30 with the slug all the to the
bottom. All of the VCO voltages came out with in specs. 1.887 volts
being the lowest on 40 meters at 7.0000 L25 and L26 are wound correctly
and have good continuity between the pads.

Where should I start looking for a problem ?

Thanks,
Glenn WA7SPY
_______________________________________________
Elecraft mailing list
Post to: [hidden email]
You must be a subscriber to post to the list.
Subscriber Info (Addr. Change, sub, unsub etc.):
http://mailman.qth.net/mailman/listinfo/elecraft

Help: http://mailman.qth.net/subscribers.htm
Elecraft web page: http://www.elecraft.com

Don Wilhelm-3

Re: Help with troubleshooting K2 receiver?

Glenn,

Whoa!!! One thing at a time and first things first.

First, the VFO voltages. The slug on L30 should normally tune near the
top - about 2 to 3 turns from the top is normal. If that is not true,
first check the number of turns on T5 - count only the turns that pass
through the center of the core.

If the turns on T5 are correct and spread about the same as the
illustration in the manual, then verify that all the capacitors in VFO
Range Selection area (see the RF Board schematic sheet 1 of 4) have
correct values and are well soldered.

Once you have the VFO voltage ranges within bounds with L30 in a normal
position, then we can work on the other conditions that you have mentioned.

73,
Don W3FPR

Glenn Maclean wrote:

> I have my K2 built to the second alignment step. It passed all the tests
> on the first part of the build on initial power up. My K2 is not hearing
> the 7.0000 birdie. I am not hearing anything on 40 meters from receive
> signals with an outside antenna connected or my broad band generator
> connected to the antenna connector. The PLL linearization worked fine
> with no errors and the end message showed up when it was finished.
>
> I do hear the signal at J15 C6 on the left side as viewed looking down
> from the top of my K2. I get a small signal increase when I inject my
> broadband signal generator to the top of the case of Q21. I get an
> increase in signal on pins 3 and 4 of the K1 relay. No increase on any
> other pins when the 40 meter band is selected. I get a signal increase
> at jumper W5 and W2. I get a small increase at W1. I get a small
> increase on both sides of D6 diode. I get an increase at the case of
> Q22. I have tripled checked component orientation and values, cold
> solder joints.
>
> I am able to get the pre amp and attenuator to work when I inject the
> signal at W5. I am able to get all the freq readings on the BFO and
> filters adjust fine. The cans for L1 and L2 have the big slots no marks.
> I had to adjust them bottomed out and then got a slight signal increase.
> It is almost as if the cans a for L1 and L2 are not the proper value. I
> was only able to get 5.5 volts out of L30 with the slug all the to the
> bottom. All of the VCO voltages came out with in specs. 1.887 volts
> being the lowest on 40 meters at 7.0000 L25 and L26 are wound correctly
> and have good continuity between the pads.
>
> Where should I start looking for a problem ?
>
> Thanks,
> Glenn WA7SPY
> _______________________________________________
> Elecraft mailing list
> Post to: [hidden email]
> You must be a subscriber to post to the list.
> Subscriber Info (Addr. Change, sub, unsub etc.):
> http://mailman.qth.net/mailman/listinfo/elecraft
> Help: http://mailman.qth.net/subscribers.htm
> Elecraft web page: http://www.elecraft.com
>

_______________________________________________
Elecraft mailing list
Post to: [hidden email]
You must be a subscriber to post to the list.
Subscriber Info (Addr. Change, sub, unsub etc.):
http://mailman.qth.net/mailman/listinfo/elecraft

Help: http://mailman.qth.net/subscribers.htm
Elecraft web page: http://www.elecraft.com

WA7SPY

Re: Help with troubleshooting K2 receiver?

I found my problem. I left C158 out some how. I now have signal and the
7.0000 birdie.I am able to peak L1 and L2 without the slugs bottomed out
in the cans.

I do have a concern The highest I can get L30 to adjust to is 5.5 volts
with the slug in L30 all the way to the bottom of the can. I am using a
battery with a voltage of 12.5 volts. I am using a Fluke model 87 meter
to take the voltage readings. I went back through and checked all
component values and orientations as if I was starting over building the
receiver section. All component values are correct as well as
orientation. T5 is wound with 16 counted turns on 1-2 and 4 turns on
2-4. It looks exactly as the diagram. Here are my VCO voltages:

80m 3500 2.23v 4000 5.5v
40m 7000 1.887v 7300 3.63v
30m 10000 3.11v 10150 3.67v
20m 14000 2.607v 15000 4.31v
17m 18000 3.196 18200 3.396v
15m 21000 2.349 21450 3.47
12m 24800 4.26v 25000 4.66v
10m 28000 3.372v 28800 4.22v

Do I have a problem or is this acceptable?

Thanks,
Glenn WA7SPY
_______________________________________________
Elecraft mailing list
Post to: [hidden email]
You must be a subscriber to post to the list.
Subscriber Info (Addr. Change, sub, unsub etc.):
http://mailman.qth.net/mailman/listinfo/elecraft

Help: http://mailman.qth.net/subscribers.htm
Elecraft web page: http://www.elecraft.com

Don Wilhelm-3

Re: Help with troubleshooting K2 receiver?

Glenn,

Yes, you do have a problem. Either with T5 or the capacitors in the VFO
Range Selection area or the Varactors. See my post from your question
yesterday. If you do not correct the VFO range problem you will
encounter difficulties later should you add the K160RX option and/or the
K60XV option.

73,
Don W3FPR

Glenn Maclean wrote:

> I found my problem. I left C158 out some how. I now have signal and the
> 7.0000 birdie.I am able to peak L1 and L2 without the slugs bottomed out
> in the cans.
>
> I do have a concern The highest I can get L30 to adjust to is 5.5 volts
> with the slug in L30 all the way to the bottom of the can. I am using a
> battery with a voltage of 12.5 volts. I am using a Fluke model 87 meter
> to take the voltage readings. I went back through and checked all
> component values and orientations as if I was starting over building the
> receiver section. All component values are correct as well as
> orientation. T5 is wound with 16 counted turns on 1-2 and 4 turns on
> 2-4. It looks exactly as the diagram. Here are my VCO voltages:
>
> 80m 3500 2.23v 4000 5.5v
> 40m 7000 1.887v 7300 3.63v
> 30m 10000 3.11v 10150 3.67v
> 20m 14000 2.607v 15000 4.31v
> 17m 18000 3.196 18200 3.396v
> 15m 21000 2.349 21450 3.47
> 12m 24800 4.26v 25000 4.66v
> 10m 28000 3.372v 28800 4.22v
>
> Do I have a problem or is this acceptable?
>
> Thanks,
> Glenn WA7SPY
> _______________________________________________
> Elecraft mailing list
> Post to: [hidden email]
> You must be a subscriber to post to the list.
> Subscriber Info (Addr. Change, sub, unsub etc.):
> http://mailman.qth.net/mailman/listinfo/elecraft
> Help: http://mailman.qth.net/subscribers.htm
> Elecraft web page: http://www.elecraft.com
>