[Elecraft] K1 1408 passed the smoke test, but the VFO will not change frequency

Sun Dec 1 02:15:01 2002

You get the prize for the right answer. I swtiched the number 1 and number 2
wires and it tunes like a champ. I think that Elecraft should add something
to the eratta to include checking the pins on the 10 turn pot for correct
wiring if the VFO does not tune right.

THANKS!!!

Jess
----- Original Message -----
From: "Juerg Tschirren" <[email protected]>
To: "Jess Gypin" <[email protected]>
Cc: <[email protected]>
Sent: Saturday, November 30, 2002 23:50 PM
Subject: Re: [Elecraft] K1 1408 passed the smoke test, but the VFO will not
change frequency

>
> Sounds like to got the wires at pin 1 and pin 2 of the pot swapped. Check
> the drawing in the manual, p. 22. The labels on the pot itself are
> confusing. I had the exact same problem :-)
>
> Juerg
>
>
> --... ...--   -.. .   -. ----- .--. .--.
>
> On Sat, 30 Nov 2002, Jess Gypin wrote:
>
> > Hi all,
> >
> > I am at the point where I need to set the upper and lower frequencies of
the
> > VFO and it will not change frequency. The oscillator shows 3093 hz. The
VFO
> > will not change frequency. I have traced the 10 turn pot to P1 of RP-2
and
> > verified the xtals on the filter board. The problem appears to be that
the
> > voltage at D3 is not changing. With the change in resistance of the
tuning
> > pot, the voltage at P2 of RP-2 and at the cathode of D3 never changes
from
> > 5.91 volts unless I hit the clockwise stop and the pot resistance almost
> > goes to 0, then the VFO will jump and change frequency. Also the voltage
at
> > the cathode of D4 never goes below 2.91 but that is to be expected if
the
> > voltage at the first varacter is not changing.
> >
> > I ohmed out the varacters for D3 and D4, and they measure about 600 ohms
one
> > way and infinite the other. I would assume that since I am getting a
voltage
> > change with the pot at the stop and the frequency changing, that the VFO
> > works, but the voltage at the varacters in not changing with the change
in
> > resistance at the 10 turn pot.
> >
> > This is driving me nuts. I had hoped to have this finished in time for
my
> > trip to Boston on Monday to pass the nights in the hotel. Any clues or
> > insights would be greatly appreciated.
> >
> > Jess AE0CW <><
> >
> >
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>