KX1 Recvr nearly deaf (Was KX1 receiver alignment)

[Vin Cortina]

Hi folks,

I have resolved the "signals getting loud when I touch the board" mystery
with help, but there is still something amiss.  Upon further testing, the
receiver appears to be profoundly deaf. It does hear some signals on 40, and
even some on 20, but not nearly as well as it should. However, I have some
clues here. Attaching the antenna does affect the signal level, so the
receiver is, to some degree at least, seeing the antenna. Also, the receiver
is detecting signals and is on frequency.  It hears my signal source OK, and
even the few strong external signals are perceptible, but again not nearly
as strong as on other receivers here. Another point of note, the background
hiss really doesn't sound like what I would expect. No static crashes, not
the background noise I would expect. Just a dull hiss like you would hear
when raising the volume on a PA system with no input.
Another point, although seemingly unrelated, is the AF gain control gives me
basically no audio until I get to about 3 o'clock. Then it gets loud very
quickly. (This could be a combination of not very sensitive headphones and
the audio taper characteristics of the pot, if in fact it is an audio
taper.). And then just before it hits maximum clockwise position, I hear a
slight "pop" and it gets noticeably louder.  I do realize that I probably
need more sensitive headphones/ear buds, but this would not explain all of
these symptoms.

Obviously, I am far more concerned with the first problem.  I am trying to
decipher the receiver path right now, but would appreciate any help.  Thank
you!



Vin Cortina  KR2F

K1-4 s/n:1977
KX1  s/n:1476
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[Mike Scott-7]

Vin,

My audio pot exhibits the same effect as yours, most of the gain happens in
the last 30 degrees of control motion. I do not get a "pop" at the end.

If your signals are effected by the RF Gain control I would start searching
for the problem at the front end with L1 and L2, also checking that J2
antenna jack isn't shorted and you have put the jumper wire into J7, jumping
pin 1 to pin 2 properly.

You should be able to place an ohm meter between the center pin of the
antenna jack to schematic point B, left edge of schematic near trimmer
capacitor CA. This path should offer low DC resistance independent of
whether the KX1 is switched on or off.

If your RF Gain does nothing to the signals then we need to start
elsewhere...

Mike Scott
AE6WA
Tarzana, CA (near LA)
Elecraft KX1 4-Watts


-----Original Message-----
From: [hidden email]
[mailto:[hidden email]] On Behalf Of Vin Cortina
Sent: Thursday, July 06, 2006 11:06 AM
To: [hidden email]
Subject: [Elecraft] KX1 Recvr nearly deaf (Was KX1 receiver alignment)

Hi folks,

I have resolved the "signals getting loud when I touch the board" mystery
with help, but there is still something amiss.  Upon further testing, the
receiver appears to be profoundly deaf. It does hear some signals on 40, and
even some on 20, but not nearly as well as it should. However, I have some
clues here. Attaching the antenna does affect the signal level, so the
receiver is, to some degree at least, seeing the antenna. Also, the receiver
is detecting signals and is on frequency.  It hears my signal source OK, and
even the few strong external signals are perceptible, but again not nearly
as strong as on other receivers here. Another point of note, the background
hiss really doesn't sound like what I would expect. No static crashes, not
the background noise I would expect. Just a dull hiss like you would hear
when raising the volume on a PA system with no input.
Another point, although seemingly unrelated, is the AF gain control gives me
basically no audio until I get to about 3 o'clock. Then it gets loud very
quickly. (This could be a combination of not very sensitive headphones and
the audio taper characteristics of the pot, if in fact it is an audio
taper.). And then just before it hits maximum clockwise position, I hear a
slight "pop" and it gets noticeably louder.  I do realize that I probably
need more sensitive headphones/ear buds, but this would not explain all of
these symptoms.

Obviously, I am far more concerned with the first problem.  I am trying to
decipher the receiver path right now, but would appreciate any help.  Thank
you!



Vin Cortina  KR2F

K1-4 s/n:1977
KX1  s/n:1476
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[Vin Cortina]

Some additional data.

Voltages at U4, U5 and U6 check out OK.  However, the base voltages at Q7
and Q9 are out of spec.

Base at Q7 should be about .7V, but is about .37V  and base at Q9 should be
about .3V but is about .15V.

I am continuing my troubleshooting, but welcome any and all advice.

Thanks again.


Vin Cortina  KR2F

K1-4 s/n:1977
KX1  s/n:1476



-----Original Message-----
From: [hidden email]
[mailto:[hidden email]] On Behalf Of Vin Cortina
Sent: Thursday, July 06, 2006 11:06 AM
To: [hidden email]
Subject: [Elecraft] KX1 Recvr nearly deaf (Was KX1 receiver alignment)

Hi folks,

I have resolved the "signals getting loud when I touch the board" mystery
with help, but there is still something amiss.  Upon further testing, the
receiver appears to be profoundly deaf. It does hear some signals on 40, and
even some on 20, but not nearly as well as it should. However, I have some
clues here. Attaching the antenna does affect the signal level, so the
receiver is, to some degree at least, seeing the antenna. Also, the receiver
is detecting signals and is on frequency.  It hears my signal source OK, and
even the few strong external signals are perceptible, but again not nearly
as strong as on other receivers here. Another point of note, the background
hiss really doesn't sound like what I would expect. No static crashes, not
the background noise I would expect. Just a dull hiss like you would hear
when raising the volume on a PA system with no input.
Another point, although seemingly unrelated, is the AF gain control gives me
basically no audio until I get to about 3 o'clock. Then it gets loud very
quickly. (This could be a combination of not very sensitive headphones and
the audio taper characteristics of the pot, if in fact it is an audio
taper.). And then just before it hits maximum clockwise position, I hear a
slight "pop" and it gets noticeably louder.  I do realize that I probably
need more sensitive headphones/ear buds, but this would not explain all of
these symptoms.

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[Ron D'Eau Claire-2]

Do you have the KXAT1 antenna tuner installed?

If not, is the required jumper in place across pins 1 and 3 of J7 (page 41,
right column, last step of the manual). That's the three-pin connector
*closest* to the antenna jack. If so is it making contact with the pins?
Without that jumper, the antenna is only coupled to the receiver input by
stray capacitance across the connector.

If you do have the KXAT1 installed, try removing it and inserting the jumper
and see how the receiver behaves. That would help isolate the problem to
either the KX1 itself or the ATU.

Ron AC7AC

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[Don Wilhelm-3]

Vin,

The voltage at the base of Q7 should be at or very near zero during receive.
The 0.7 volts is what is expected during transmit.

Try grounding the base of Q7 and see if the receiver comes more alive.  If
it does, you must chase down the source of the voltage on the base - first
check pin 7 of U3 which also should be zero during receive.  If it is not
then check the orientation of U3 (if U3 is backwards, get a replacement).

73,
Don W3FPR


> -----Original Message-----

>
> Some additional data.
>
> Voltages at U4, U5 and U6 check out OK.  However, the base voltages at Q7
> and Q9 are out of spec.
>
> Base at Q7 should be about .7V, but is about .37V  and base at Q9
> should be
> about .3V but is about .15V.
>
> I am continuing my troubleshooting, but welcome any and all advice.
>
>

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