KX-1 Q1 Bad - Now no received signal / RF Gain

[KY6R]

I had my KX-1 receiver working beautifully through the first 2 stages (up
through getting the receiver to work), then I added the last components -
for the transmitter. I turned it on to complete Test III, and there was no
received signal. Everything but the RF Gain control works. The audio gain
and  and filter control respond just like before, keyer works, strong
sidetone and audio, frequency encoder works, bands switch just fine, etc.

 

I checked all components and sure enough - Q1 was in backwards. I tried to
unsolder and put it back in, but I am sure it was fried. After putting it in
correctly, voltage was OK on 2 or the 3 connections - the third was zero
volts. So the JFET must have opened.

 

I'm hoping that just by replacing JFET Q1, the receiver will work again. Is
it possible that by having a bad Q1 that that could cause no signal to be
detected in the receiver? When I look at the schematic, I almost think that
the receiver should still work even with Q1 out of the circuit - is this a
correct or wrong assumption? If it still should work, then there might be
more wrong than just Q1.

 

Thanks in advance.

 

73,

 

Rich

KY6R

 

P.S - I called my local electronics store and they can't cross reference
J309 - does anyone know what would cross reference this part number?

 

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[kc5wa]

I believe that the J309 is pretty much interchangeable with a J310 or
MRF102. At least I've done this with no change in other circuits and
operation did not seem to suffer
"rc" kc5wa

Rich Holoch wrote:

>I had my KX-1 receiver working beautifully through the first 2 stages (up
>through getting the receiver to work), then I added the last components -
>for the transmitter. I turned it on to complete Test III, and there was no
>received signal. Everything but the RF Gain control works. The audio gain
>and  and filter control respond just like before, keyer works, strong
>sidetone and audio, frequency encoder works, bands switch just fine, etc.
>
>
>
>I checked all components and sure enough - Q1 was in backwards. I tried to
>unsolder and put it back in, but I am sure it was fried. After putting it in
>correctly, voltage was OK on 2 or the 3 connections - the third was zero
>volts. So the JFET must have opened.
>
>
>
>I'm hoping that just by replacing JFET Q1, the receiver will work again. Is
>it possible that by having a bad Q1 that that could cause no signal to be
>detected in the receiver? When I look at the schematic, I almost think that
>the receiver should still work even with Q1 out of the circuit - is this a
>correct or wrong assumption? If it still should work, then there might be
>more wrong than just Q1.
>
>
>
>Thanks in advance.
>
>
>
>73,
>
>
>
>Rich
>
>KY6R
>
>
>
>P.S - I called my local electronics store and they can't cross reference
>J309 - does anyone know what would cross reference this part number?
>
>
>
>_______________________________________________
>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
>
>
>
>  
>

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