Other questions was RE: [Elecraft] K2 Alignment and Test, Part III: High current

[Don Wilhelm]

Kathy,

Great that you found the transmit problem - and if you can use larger wire
for the power supply, the voltage drop will be less and will likely reduce
your current draw on transmit a bit more.

Yes, your preamp dropout problem does sound like a bad solder connection is
the most likely cause.  Places to check are those components associated with
Q21 - look on the schematic (sheet 2) for the RF Board to identify those
associated components, and don't overlook pins 4 and 7 of relay K17 and
toriod T6.  Actually anything in the receive chain from the antenna through
the IF Amp will effect the AGC action (and subsequently the S-meter), but if
the S-meter appears normal with the Preamp off, then the problem is likely
confined to the preamp stage.

Solve the preamp problem first and then tackle the AGC - since your S-meter
seems close to normal with the preamp off, fixing the preamp may take care
of the S-meter anomoly too.  True the AGC (and S-meter) should not behave as
you describe, but you can optimize the AGC threshold after you know
everything else is working properly, then finally adjust the S-meter as the
last step.

73,
Don W3FPR

> -----Original Message-----
>
> Hi Don and everyone else who responded,
>
> The current readings @ 5W and 10W are now at the upper end of
> normal levels.
> T4 was reversed and needed to be turned around. The power wire is also on
> the thin side, 16g or 18g. I'll find a replacement tomorrow.
>
> Two new interesting problems have cropped up as well:
> a) 20m band, tuned Zepp: The S-meter is pegged on +40dB when the
> preamp is
> on. With the preamp off,  the meter settles down to around S5 (S5-S9 when
> copying a signal). On 40m, antenna tuned, the LED reads +40dB with preamp
> and +20dB without. Tried following the S-meter setup instructions in the
> manual, including those on the XG1 mini-kit, but nothing seems to prevent
> the LED from locking into the upper limit when the preamp is on. Is this
> normal? The AGC can be switched on and off as well as set fast or
> slow. With
> AGC off, the S-meter drops to zero.
>
> b) The gain drops intermittently from an S-meter reading of +40dB
> to S2 with
> preamp on. The audio also diminishes in intensity at the same
> time. The last
> time it did this, I tapped the left side of the radio a couple of
> times and
> it stopped dropping out. This sounds like a loose component, bad
> connection
> or bad solder joint. Where should I begin my search? The IF
> stage? Could it
> be a toroid with a bad solder joint?
>
> Thanks,
> Kathy
>