[Elecraft] K160RX Not Recognized by MCU

[Dean Maples]

Hi folks - my problem is that I can't select 160 meters. The band up / down
buttons go from 80 m to 10 m and skip over 160.

Here's what I've done so far, and I'm now stuck.

1 - The 160 M band has been working fine for about the last year. My K2 SN =
3043. I have the following accy's installed and working - KDSP2, KSB2,
KBAT1, KIO2, KAT2, KNB2.

2 - There are no other problems with the K2, that I can detect. I've used it
on SSB on 2 bands (40 & 80) and all is okay. I don't use it on CW, but I do
have power out into a dummy load.

3 - My MCU version is 2.03d and I/O is 1.07.

4 - I have 0.4 ohms continuity between pin 2 of U1 on the RF board and pin
10 of the K1 relay on the 160 board - this is at the relay pin solder joint.
This was in the troubleshooting on page 8 of K160RX manual. The relay coils
of K1 and K2 are 247 ohms. R65 is installed on the bottom of the RF board.

5 - On the high side of R65 I measure about 6 Vdc. on the low side of R65
(160RY - which connects to pin 16 of J1 on the 160 board, I measure a rapid
positive going change. I hooked a scope, dc coupled, to this junction and
never saw a negative going pulse only a ~6Vdc positive going pulse.

6 - I went to the Omron website and looked up the voltages that must be
applied to the relay coil pins (1 & 10) to "set" and "reset" the relay - if
I'm correct (check me out here) if I apply +5Vdc to relay pin 10 and 5Vdc
return to pin 1 of the relay, it will move to the "reset" position. This
should match the schematic in the 160 M manual, page 11. When I reverse the
polarity (+ to pin 1, and return to pin 10) the relay should move to the
"set" position.

7 - In step 6, I verified correct readings using an ohmmeter with the 160RX
board removed from the K2 and laying on the bench. I used an outboard +5Vdc
supply to toggle the relay.

8 - So when the relay (K1) was supposed to be "reset," I had an open between
pin 3 & 4 of the relay and an open between pins 8 & 7. At the same time,
pins 3 &2 had continutity (0.4 ohms) and pings 8 & 9 had continuity. I
toggled the relay again using my outboard 5Vdc supply but reversed the +
and - minus leads to move the relay to the "set" position. I then got
continuity between pins 3 &4 and an open between pins 3 & 2, and got
continuity between pins 8 & 7, and an open between pins 8 & 9.

9 - It looks like the relay is working the way it should be when the K160RX
is removed from the K2. Also, I measure ~6Vdc at both ends of R65 when the
160 board is removed from the K2. Again, this looks normal to me.

10 - With the K160RX installed in the K2, I never see the negative going
pulse to toggle the K1 relay to the other state.

11 - Have I got a problem with U1 being able to drive the relay - no
negative going pulse from U1, pin 2?

12 - The K160RX relay ground (RY COM) looks okay. When I access the menu I
can go to Rant and I see On or Off. I can toggle the K160RX K2 relay on the
160 board with the menu buttons (I can hear it toggle). The menu display
acts the way I would expect on, then off. With the 160 M module removed, the
menu item for Rant shows "--" as I would expect. Hence, I'd conclude that RY
COM is working okay and isn't a problem.

13 - So now --- HELP !!

Any suggestions would be most welcome at this point. Anything else I can do
to check the K2 out to be sure the rig's Aux bus is working okay and the MCU
and I/O controller are all okay?

Dean, K9FTB
Fairport, NY