Collins KWM-2

 

14 January 2024 - Tested with the 30L-1 amp - getting 500W on 80M - see my 30L-1 blog section.

6 January 2024 - Got the KWM-2 and 516F-2 back in their cases.

2 January 2024 - After replacing the driver tube I am getting the expected output:

80M    100W+

40M    100W

20M    100W

15M    100W

10M    80W

 

1 January 2024 - Yesterday I started looking at the power output - at first I was seeing nothing on my Bird watt meter, so I decided to test with another watt meter - on this one I was seeing power output from the KWM-2.  I started tuning and got to a good stopping point today.  I am getting the following output:

80M    70W

40M    70W

20M    50W

15M    50W

10M    30W

 

26 December 2023 - Over the past week I removed the meter and while it was out, I thoroughly cleaned the PLATE/GRID/ALC switch and also sprayed the MIC Gain pot with ample amounts of contact cleaner - I am now seeing Grid current.  

I had also ordered a new MIC Gain pot just in case of other issues with that part - it should arrive today.

Next, I'll hookup my Bird watt meter to see what I am getting there - I've just been using a dummy load so far.

And finally, I ordered a new full set of tubes (except finals) to have on hand - all the current tubes test good.

Below is the cleaned meter face with the glass now held in place by the ring inside.  Still needs a little glue cleaned off the front glass.

28 November 2023 - Started on the PA cage relay replacement yesterday and finished it up today - the relay is working and I am getting a little grid current now - next step is to do an alignment, but first I'll get the PA cage and relay covers back on.

 

27 November 2023 - More work on the KWM - no grid current seen so I opened up the cover on the bottom to check the two relays there - they both look good and function when keyed.  I then checked continuity across the relay in the PA cage and it was open - but is getting power.  Another test I did was to put an ohmmeter across the "ANT RELAY" jack to ground and the meter should have read open - it did - I then keyed the radio and the meter should have read zero ohms - it read open either way so it is bad.  I took the PA case off in preparation for the relay swap - the replacement relay will be here today.

 

20 November 2023

19 November 2023 - I was able to do the initial checks to set the power supply bias to produce 40ma of plate current on the KWM-2.  The only deviation I had to do was set the RF-gain fully counter-clockwise.

Set MIC GAIN control (4) full counterclockwise until the switch clicks. Set OFF-ON-NB-CAL switch (1) to ON. Set meter switch (8) to PLATE, and EMISSION switch (2) to LOCK. The transceiver is in receive condition during warmup, so the meter will read full scale until filaments have come to temperature. This is normal S-meter action. When the S-meter falls back to zero, the circuits will have switched to transmit condition, and the meter will indicate PA plate current. Read the no-signal PA plate current. It should be approximately 40 ma. If plate current is other than 40 ma, adjust BIAS ADJUST potentiometer on top rear of power supply chassis to set plate current to 40 ma. If the transceiver is to be used with a linear amplifier, set bias to produce 50-ma idling plate current. 

 

17 November 2023 - The 6146 arrived yesterday and I installed it - the 6CL6 arrived and I installed it but I will wait for the other tubes to arrive and install them before doing more tests.

13 November 2023 - Finished checking the other tubes - the following need replacement and have been ordered:

V1A First microphone amplifier 6AZ8

V1B First receiver i-f amplifier 6AZ8

V16A Receiver first a-f amplifier 6EB8

V16B Receiver a-f output amplifier 6EB8

11 November 2023 - Checked the driver and final tubes - one of the finals (6146) and the driver (6CL6) were bad so I ordered replacements.  Will check the other tubes next.

9 November 2023 - Did some receive testing on 80M and 40M using the wire antenna outside and was able to receive signals on both bands.  I tried some transmitter tests but didn't see any power output.  My next step is to start testing the tubes and make note of the ones needing replacement.

7 November 2023 - Finished recaping the electrolytic capacitors in my KWM-2 last night and hooked it up to the 516F-2 power supply and my speaker and sent a 3876 khz signal from my AWG with AM modulation and was able to receive it in CW on the KWM-2 - see video below.  I am extremely happy!

29 October 2023 - Finished replacing the can capacitor and one of the 4MD capacitors.

28 October 2023 - Working on replacing the can capacitor. Below is the original - The 4MF ground was cut and the cap was lifted out of the way to see this view of the can leads.

Below is the new can capacitor in place but not reconnected yet.

11 October 2023 - Pulled the KWM-2 out of the case to prepare for the capacitor replacements - found one capacitor that had leaked an had burnt marks.  It's pretty tight in there so replacing the capacitors will be fun.  The rest of the unit looks pretty clean.

10 October 2023 - Ordered the KWM-2 recap kit Saturday.

13 August 2023 - Purchased a KWM-2 to go with my 516F-2 power supply project.  The capacitors for the 516F-2 and the KWM-2 itself should arrive this week.  The KWM-2 is in great cosmetic shape with just a ding on a back bottom corner and the meter face is glued in place.