[Elecraft] K2 Transmitter Alignment

Sat Jan 24 19:37:00 2004

Joe,

If I couple your measurements with the relays mounted with yout tests that
show the relays to be good, I can only think that you have a short ot ground
somewhere in the 20/30 meter low pass filter.  Suspects would be C197, C199,
C201 and C203, but with less likelihood, there might be a solder bridge at
L18, L19, L20 or C198, C200 or C202.

A quick check on the bandpass filters is to attach the antenna to jumper W1
(t/r switch side with the jumper still removed) and see if you have good
receive signal on 20 and 30 meters as compared to the other bands.  If you
do, there is likely nothing wrong with the bandpass filter and you should
look more closely at the low pass filter area.

73,
Don W3FPR

----- Original Message ----- 

Hello, here's Joe continuing his check for why no output on 20/30m bands.

In the LPF, I removed L16 to L26 in hopes to confirm correct operation of
the LPF relays.  I was only able to confirm that the "B" section of all 5
relays switched correctly the pins 7-8-9 for each selected band.  Pins 2-3-4
remain suspect.

I then removed relays K8-K12 quite easily with the Hakko 808 desoldering
gun.  Using a small 5vdc supply I latched each relay back and forth to
confirmed that pins 2-3-4 and pins 7-8-9 latched correctly.  A +5vdc on pin
10 latched pins 2-3 and 8-9 while a +5vdc on pin 1 latched pins 3-4 and 7-8.
Yet, the common bus for LPF in is still grounded.  Rats.

I remove the jumper at W1.  Bus is still grounded.  J14 is okay.  I follow
LPF Bus source to sheet 4 and see leads 3 and 4 of T4 takes LPF practically
straight to dc ground.  What a dead end I've come to.

So I suppose now I'll check the BPF relays etc, looking to get some output
on 20/30m.  I don't have much faith that the relays are the problem, but
I've gotta start somewhere.  Any other ideas?

73, Joe, aa4nn

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