Elecraft

K2 receiver problem

Classic

List

Threaded

4 messages Options

GS-3

K2 receiver problem

Hi list,

got a K2 from another OM on my workbench. It's got a
receiver problem and I just want to make sure I do the
checks in the correct order and I'm looking for hints,
if available!

Thanks in advance!

So here's the problem and what I want to do. It seems
the receiver runs with "handbrake on". So the s-meter
shows 3 bars without an antenna but the rf gain is
fully clockwise. I can reduce signals to zero (using
RF gain) with this K2 which I can't using my own K2.
So mine has a higher sensitivity.

Any idea what's wrong?

What I want to do:
- s-meter alignment
- I.F. amplifier alignment
- (maybe band pass alignment)
- signal tracing receiver and synthesizer

Kind regards

Gerhard
DH3FAW

___________________________________________________________
Gesendet von Yahoo! Mail - Jetzt mit 1GB Speicher kostenlos - Hier anmelden: http://mail.yahoo.de
_______________________________________________
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

S55M

Re: K2 receiver problem

Did You try to listen with AGC off?

----- Original Message -----
From: "GS" <[hidden email]>
To: "Mailingliste Elecraft" <[hidden email]>
Sent: Wednesday, November 09, 2005 10:58 AM
Subject: [Elecraft] K2 receiver problem

> Hi list,
>
> got a K2 from another OM on my workbench. It's got a
> receiver problem and I just want to make sure I do the
> checks in the correct order and I'm looking for hints,
> if available!
>
> Thanks in advance!
>
> So here's the problem and what I want to do. It seems
> the receiver runs with "handbrake on". So the s-meter
> shows 3 bars without an antenna but the rf gain is
> fully clockwise. I can reduce signals to zero (using
> RF gain) with this K2 which I can't using my own K2.
> So mine has a higher sensitivity.
>
> Any idea what's wrong?
>
> What I want to do:
> - s-meter alignment
> - I.F. amplifier alignment
> - (maybe band pass alignment)
> - signal tracing receiver and synthesizer
>
> Kind regards
>
> Gerhard
> DH3FAW
>
>
>
>
>
>
>
> ___________________________________________________________
> Gesendet von Yahoo! Mail - Jetzt mit 1GB Speicher kostenlos - Hier

anmelden: http://mail.yahoo.de

> _______________________________________________
> 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

Don Wilhelm-3

RE: K2 receiver problem

In reply to this post by GS-3

Gerhardt,

It sounds like the AGC Threshold is not set properly.

I would proceed by first checking the alignment of the bandpass filters in
Transmit mode (at 2 watts) and then set the AGC Threshold for optimum
receiver sensitivity - with no antenna connected and AF and RF Gains set to
max, adjust for the highest voltage at Control Board U2 pin 5 which yields
no change in the audio noise when switching the AGC between OFF and ON.
That will usually result in a voltage in the range of 3.65 to 3.8 volts at
U2 pin 5. Set the S-meter end points (CAL S Hi and CAL S-Lo) after setting
the threshold.

If that does not cure the problem, then look for a problem in the IF receive
chain - that will be where the signal tracing is required, follow the
p[rocedure for receiver signal tracing in the Troubleshooting appendix of
the K2 manual.

73,
Don W3FPR

> -----Original Message-----
>
> got a K2 from another OM on my workbench. It's got a
> receiver problem and I just want to make sure I do the
> checks in the correct order and I'm looking for hints,
> if available!
>
> Thanks in advance!
>
> So here's the problem and what I want to do. It seems
> the receiver runs with "handbrake on". So the s-meter
> shows 3 bars without an antenna but the rf gain is
> fully clockwise. I can reduce signals to zero (using
> RF gain) with this K2 which I can't using my own K2.
> So mine has a higher sensitivity.
>
> Any idea what's wrong?
>
> What I want to do:
> - s-meter alignment
> - I.F. amplifier alignment
> - (maybe band pass alignment)
> - signal tracing receiver and synthesizer
>
> Kind regards
>
> Gerhard
> DH3FAW
>

dmb@lightstream.net

Re: K2 receiver problem

In reply to this post by GS-3

Hello Gerhard,

First, do the AGC threshold adjustment (instructions located at end of
Assembly, Part I in the manual)

Then do the S-Meter Alignment, the instructions of which follow the AGC
threshold adjustment instructions.

It sounds like the AGC is set a bit too aggressively at the moment.

73, Dale
WA8SRA

GS wrote:

>Hi list,
>
>got a K2 from another OM on my workbench. It's got a
>receiver problem and I just want to make sure I do the
>checks in the correct order and I'm looking for hints,
>if available!
>
>Thanks in advance!
>
>So here's the problem and what I want to do. It seems
>the receiver runs with "handbrake on". So the s-meter
>shows 3 bars without an antenna but the rf gain is
>fully clockwise. I can reduce signals to zero (using
>RF gain) with this K2 which I can't using my own K2.
>So mine has a higher sensitivity.
>
>Any idea what's wrong?
>
>What I want to do:
>- s-meter alignment
>- I.F. amplifier alignment
>- (maybe band pass alignment)
>- signal tracing receiver and synthesizer
>
>Kind regards
>
>Gerhard
>DH3FAW
>
>
>
>
>
>
>
>___________________________________________________________
>Gesendet von Yahoo! Mail - Jetzt mit 1GB Speicher kostenlos - Hier anmelden: http://mail.yahoo.de
>_______________________________________________
>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
>
>
>
>