75A-1
Update - July 2026 - Put the tubes in and hooked up the speaker - did not have an antenna but did seem to have some noise out of the speaker - more testing soon.
April 19, 2026
Update - Purchased this from Brian KN4R before the Dalton Hamfest and received it there - he reported no audio - have have tested most of the tubes and found two tubes that were testing bad and needed to be replaced - I have received them but have not had time to put them in and test.
32V-1 Transmitter
April 19, 2026
Update - this has been on the bench a while - everything is working except voice - this is still on my main bench waiting for time to work on it further.
September 5, 2025 - Additional testing and after using Deoxit on the band switching, now all bands are functioning. The remaining item to get working is the microphone - I know the element is working as I looked at it on my oscilloscope while speaking into it - the wiring inside the D-104 base looks correct - next is to check the plugs wiring.
August 31, 2025 - Replaced the 100 ohm plate suppresser and installed a new ceramic plate connector - still same issue with the grid and plate meters. I decided to go back to the original tube and the issue went away - this tube does not have the "blue" emission in the top like the other (bad) tube - I guess the bad tube is gassy. Seeing 90W with HV on 600V on one of the bands - will look at tuning the other bands.
August 25, 2025 - This issue has been resolved. I did not realize the cause until I looked at the schematic, but every time I put the transmitter into voice it would key continuously, so what I found was the PTT line is tied to the high voltage switch so turning off the high voltage switch, and then using the PTT on the microphone to key the transmitter resolved that issue.
A new issue - After replacing a few tubes, I'm now getting good power out but seeing negative meter movement on the grid current and sometimes the plate current meter pegs and the only way to fix that is power cycle the HV - my plan is to look at the components around the output tube and start checking those. Maybe some of the capacitors are leaky or have gone open or closed.
August 23, 2025 - The relay has been cleaned and is back in place. I installed a new SO-239 connector and still need to replace the power cord. With 700V I was seeing over 100W and with 600V I get 53W on the band tested. Also the new dial needs to be installed.
August 21, 2025 - Cleaning the relay and checking that it actuates when HV tis turned on. It looks really dirty still - been using lots of contact cleaner but still no RF output.
August 17, 2025 - After replacing the LV 4uf capacitors I was seeing grid and plate current and a small amount of output power. I decided to check the tubes in the exciter and found the 1st multiplier tube was bad and have ordered a new 6AG7. Also found some writing on the bottom of the plate covering the exciter which noted the tubes were changed in 1954 & 1966.
August 16, 2025 - Got the two 4uf capacitors replaced yesterday and seeing frid and plate current again.
August 14, 2025 - Been working on checking the electrolytic capacitors in the 32V-1 - found the HV 8uf is good bit the two LV 4uf capacitors (second picture below) need replacing. Also got a picture of the tag - the serial number is 435.
July6, 2025 - Re-checked the power out and it was 27W.
July 5, 2025 - Yesterday I hooked up a key to see if there was any output. Today I hooked up the Bird watt meter and was seeing around 30w - I will check again once I get the tubes I found faulty in the LV & HV power supplies replaced.
July 3, 2025 - Got the replacement lamps for the LV (green) and HV (red) indications. The lamps are 15 Watt - T4.5 Incandescent Light Bulb Clear - Candelabra Base - 130 Volt - PLT IN-0015T45CL and I ordered them from 1000bulbs.com .
June30, 2025 - Tested the LV, HV and modulator tubes yesterday - found a few that need replacing and ordered some and have bids on others.
June 28, 2025 - Almost two years later this project is finally on my bench. The LV and HV are working, but not sure I am getting the expected voltages. I will be testing tubes and capacitors in the power supply section next.
4 July 2023 - Finally got around to getting the 32V-1 out of the cabinet - first task was to replace the LV & HV lamps - next will be to check the two 4uF capacitors in the LV section.
I have the replacement dial from Howard Mills and I also have velum paper and the lamps for the dial segments.
18 October 2022 - Looking at a few items before firing this up - the 4uF capacitors in the LV section look leaky and they are deformed - ordered replacement capacitors for them and the two in the HV section. I may re-stuff them or may just bypass them under the chassis, installing the new capacitors there.
17 October 2022 - Picked up the Collins 32V-1 receiver on 10/15 - this radio is extremely heavy - looking forward to testing it and getting it operational. I already have the replacement dial rule.
22 September 2022 - Adding a 32V-1 transmitter to my Collins collection - just won the auction at $199.99 - a steal.
75A-3 Receiver
7 September 2025 - Finally got the Collins speaker hooked up, that I bought a a Dalton hamfest several years back.
20 November 2021 - So far I replaced the limiter pot - it was frozen. Added another filter in the "B" position.
I ordered and received a complete tube set, capacitor replacement kit, and a SSB adapter. These will be installed at a later date.
Tested on multiple bands and works great - even SSB without the adapter works
