No BFO

[thomask.smith]

I'm building K2 #5020 and have no BFO. So far everything else works.

What I've done so far:

Checked for correct components - OK
Checked for correct orientation of parts - OK
Checked solder connections - OK
Checked for solder bridges - None found
Checked L33 - OK -Good continuity and no damage visible
Checked varactors D38 and D37 - Checks good as diodes
Checked associated caps - None shorted
Checked resistor packs - OK
Measured voltages at U11 -

        Pins 1 thru 5 & 8 - OK
        Pin 6 - 5.01 vdc - should be 6.1
        Pin 7 - 4.66 vdc - should be 5.6

I also have no audio from the receive circuit. I figure this is due to
lack of BFO. The side tone works fine so I know the audio amp is
working.

Help!!

Thanks,
Tom WA7DET
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[Don Wilhelm-3]

Tom,

Check to be certain you have the correct crystals at X3 and X4 -- they will
likely be marked ECS  D 4.91 -S.

If you have not already done so, buiild the RF Probe from the parts supplied
with your K2 and use it to measure the RF voltage at U11 pin 6 (NE612) - it
should be somewhere between 0.2 and 0.7 volts.  If you get a reading
significantly lower than that, U11 could be bad.

Yes, you will not have much audio with no BFO - maybe just a bit of a
'rushing' noise, but very little.

73,
Don W3FPR

> -----Original Message-----
>
> I'm building K2 #5020 and have no BFO. So far everything else works.
>
> What I've done so far:
>
> Checked for correct components - OK
> Checked for correct orientation of parts - OK
> Checked solder connections - OK
> Checked for solder bridges - None found
> Checked L33 - OK -Good continuity and no damage visible
> Checked varactors D38 and D37 - Checks good as diodes
> Checked associated caps - None shorted
> Checked resistor packs - OK
> Measured voltages at U11 -
>
> Pins 1 thru 5 & 8 - OK
> Pin 6 - 5.01 vdc - should be 6.1
> Pin 7 - 4.66 vdc - should be 5.6
>
> I also have no audio from the receive circuit. I figure this is due to
> lack of BFO. The side tone works fine so I know the audio amp is
> working.
>
> Help!!
>
> Thanks,
> Tom WA7DET
>

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[Roland Whitsitt]

OK, I just crossed that bridge a few days ago.  I didn't think I had a BFO.
Look for an envelope marked E850099 and/or 41UH INDUCTOR, 5%.  Or it may say
L33 on it.  Is that what you mean?  It should be very fine wire wrapped many
times around a toroid.  Hope it helps.
Roland in Stockton
K2 #3090
----- Original Message -----
From: <[hidden email]>
To: <[hidden email]>
Sent: Sunday, July 31, 2005 1:13 PM
Subject: [Elecraft] No BFO


I'm building K2 #5020 and have no BFO. So far everything else works.

What I've done so far:

Checked for correct components - OK
Checked for correct orientation of parts - OK
Checked solder connections - OK
Checked for solder bridges - None found
Checked L33 - OK -Good continuity and no damage visible
Checked varactors D38 and D37 - Checks good as diodes
Checked associated caps - None shorted
Checked resistor packs - OK
Measured voltages at U11 -

Pins 1 thru 5 & 8 - OK
Pin 6 - 5.01 vdc - should be 6.1
Pin 7 - 4.66 vdc - should be 5.6

I also have no audio from the receive circuit. I figure this is due to
lack of BFO. The side tone works fine so I know the audio amp is
working.

Help!!

Thanks,
Tom WA7DET
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Post to: [hidden email]
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_______________________________________________
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