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A Collins 32V-3

Discussion in '"Boat Anchor" & Classic Equipment' started by WA2FXM, Sep 8, 2017.

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  1. WA2FXM

    WA2FXM Ham Member QRZ Page

    Now that I've got the R-390 up and running I've acquired a Collins 32V-3 to pair it with. I haven't powered it up yet, just working around the outside. I've replaced the cracked frequency dial glass. The antenna connector got dinged and the whole assembly got bent so that needs to be replaced. The front panel screw that seems to hold the Antenna Loading shaft in place is loose and somehow binds up the control if I try and tighten it so that needs to be looked at. From what I've read so far this transmitter is a bit of a beast. But I guess I need something to do with all my free time this winter.

    32V3.jpg
     
  2. WA5VGO

    WA5VGO Ham Member QRZ Page

    A great transmitter, but the most difficult to work on radio you will ever encounter.
    Take a close look at the LV transformer. Most of the originals have failed.
     
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  3. K9STH

    K9STH Ham Member Volunteer Moderator QRZ Page

    I do not usually recommend replacing tube-type rectifiers with solid-state. However, the Hallicrafters HT-32- series, HT-37, and the Collins 32V- series are exceptions.

    In those transmitters, there is a pretty good chance that the 5.0 VAC rectifier filament transformer windings are going to eventually short to other windings or the transmitter's core. This is because the rectified B+, both high and low, are on the filament windings.

    Replace both 5R4 and the 5Z4 tube rectifiers with diodes. The 5R4 can be replaced with 3 to 4 1N4007 diodes in series for each half of the tubes and the 5Z4 can be replaced with 2 to 3 1N4007 diodes in series. Remove the filament connections to Pin-2 and Pin-8 and tape the ends of the wires from the transformer.

    If the low voltage transformer seems to be "toast", removing the 2-each 5.0 VAC windings from the rectifier sockets and replacing the tube rectifiers with solid-state, the transformer can often be used and does not have to be replaced.

    The cathode, of the 1N4007 diode strings, need to be connected to Pin-8 for the 5R4 tubes and the same for the 5Z4 tube.

    Glen, K9STH

    technical adviser-1a.jpeg
     
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  4. WA2FXM

    WA2FXM Ham Member QRZ Page

    First power up and the LV transformer appears to be OK although the supply is a bit soft. Meter shows LV at 260v with just LV power on. It drops to 190v with HV power on and then down to 175v on key down. I've got a 5Y3 subbed for the 5Z4 rectifier. 55 watts out into dummy load on first try. Something to work with.
     
  5. N2DTS

    N2DTS Ham Member QRZ Page

    I have one, I once had two 32V3's and a 32V1, they used to be cheap ( two for $90.00 once).
    The one I have has been working trouble free for the last 30 years I have had it.
    It still has all the original tubes and parts in it.
    I solid stated all the power supplies when I got it and run it at 700 volts.
    I used it mostly as an RF exciter for the big rigs, so it was on a lot, but not at high power.
    I gave away the cabinet and the driver transformer or I would likely have sold it long ago.
    I have it mounted in a rack (with bottom supports) and drive the 807 modulators with an 8 ohm to 5000 ohm center tapped transformer.
    I had tried various AB1 modulator setups KT88, KT90 tubes but never got it to sound great that way, those tubes need very high screen voltage.
    As it is, it does 100 watts out and 400 watts pep, and sounds very good.

    The big thing with the rig is the low voltage transformer, you have to get the filament power off it.
    Mine runs slightly above room temp, the extra voltage only seems to make things work better.
    Something has to go at some point, but its been trouble free for over 30 years of use.

    The output tube (4D32) is cheap and very rugged, I run three at 1200 volts modulated by a pair of 811's at 300 watts carrier and 1200 watts pep
    and have been doing so for years without a tube failure.
    Don't fear the voltage!
    I think its an 8 or 10 uf oil filled 1000 volt cap in the HV supply, no worries there at all!

    I don't find them that hard to work on. Once its out of the cabinet most things are easy to get at.
    Its very modular, and its not that hard to remove the power supply assembly off the back if you need to.

    One thing to check, the plate tuning cap can have an offset force on it from the clamp which can push the plates off center causing it to arc on modulation peaks.
    Look for that, and if the plates are off center, loosen the coupler and have it pull or push a bit in the other direction to correct it.

    Maybe nit picking but I changed the screen voltage tap for the final to a different spot so it gets part modulated and part unmodulated voltage, I could not get
    very high positive modulation with it stock.

    Otherwise its the best 100 watt AM transmitter in stock form that I know of (besides home brew).

    Lots of AM on 7290 and 3885 or there abouts, 100 watts is often a big signal on 40 meters.
    Winter weekend daytime used to be very popular on 40 meters with maybe 40 stations on at various times and spots, with lots of old rigs on.
     
  6. WA3VJB

    WA3VJB Ham Member QRZ Page

    Mark, your callbook address lists you in Vermont -- and the New England area is among the best for AM activity on 75 meters to use and enjoy your senior Collins transmitter. I've had one for many years, a 32V2, and yes the low voltage transformer went out. I understand the problem was traced to the original manufacturing process, where the turns tension was too tight among windings. The proximity of HV, and years of environmental exposure, eventually degrade the insulation and cause a breach. I had mine rewound by the late Jess Price, in the same housing and on the same core. I left it unpotted however.

    One area you may find some twitchy behavior is among the loctal tube multiplier stages. The bakelite/ceramic trimmer capacitors can develop dead spots that can drive you crazy. You can peak the drive in an alignment, have things just right, and then completely LOSE drive when things warm up or you move the transmitter to cause some physical input on the chassis. The dead spot makes itself known! When you said you were getting 55 watts, I immediately thought you have a candidate for an alignment.

    It's really not a very difficult transmitter to work on, with discrete components, adequate room and nothing really exotic like the "couplets" used in some of the WRL gear of the same era. Among the senior Collins models, the matching 75A receiver is far more difficult to repair and align, because you have layers to unravel before you can get to things.

    Good luck, and I hope to work you this Winter radio season..

    ADDING: come join us on the QRZ.com AM Forum
     
  7. WA5VGO

    WA5VGO Ham Member QRZ Page

    I keep reading about how easy this transmitter is to work on. Have any of you ever tried to replace a bypass or coupling capacitor in one of the multiplier stages? Maybe a bad resistor on one of the 7C5 sockets? Have you ever tried to simply remove a cover from one of the multiplier coils? I've worked on plenty of boatanchors and none even come close to dealing the misery this one can hand out. The way Collins constucted it is a disgrace.
     
  8. K9STH

    K9STH Ham Member Volunteer Moderator QRZ Page

    VGO:

    Have you ever worked on a Hallicrafters HT-20? Or a Hallicrafters SX-71? The Hammarlund Super-Pro series are another series of equipment that one must ask if you have any experience working on the equipment.

    The Collins 32V- series, as well as any of the 75A- series or 51J- / R-388 series, are not that difficult for someone experienced in working on "boat anchor" equipment.

    The 32V- series is constructed more to military specifications and is NOT a disgrace! How many military surplus unit types upon which you have worked? Not every radio is as wide open as a Hallicrafters S-38- series or Heath AR-2 / AR-3!

    Yes, working on quite a number of different "boat anchor" models does require more knowledge and skills than other models. But, such is life and that is "the way the cookie crumbles"!

    Glen, K9STH
     
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  9. KM1H

    KM1H Ham Member QRZ Page

    The biggest problem with the V3 is just getting to the circuitry thanks to all the added TVI metal. I use a V2 which is the same minus the TVI kit.

    The 32V line has several transformer issues and none due specifically to the 5V that Im aware of, ALL of the insulation is poor quality and the choke, LV, and audio transformers are also candidates for a rewind. A little air circulation and not running it at the HV position and leaving it on all day are my suggestions. Also, if your AC line is high add an external bucking transformer to bring it down to 110-113V; the heat reduction will be a huge eye opener. I do that with all my vintage gear.

    I agree that the HT-32 series and HT-37 had bad design/built HV transformers since new and I converted my 32A and B ages ago to SS. The Gonset GSB-101 is another transformer eater since new.

    I also get rid of any 866A and replace with a 3B28 or the plug in 1N2637 or equivalent.

    I run mine at 90W and fully loaded (and 112VAC) which is where it looks the best on the scope and SA and that is with NOS tubes. It is also a one owner having been stored since the 80's and also included a 75A3 with CW and AM filters plus NBFM adaptor and speaker. I also built a small SS preamp so it wouldnt be so deaf on 10M plus with the V3 I dont have the drift problem of the various Johnsons here.

    Carl
     
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  10. WA2FXM

    WA2FXM Ham Member QRZ Page

    Ok, true. I haven't yet had to dig into the innards of the multiplier section. So maybe I'm jumping the gun here but so far this 32V is no more difficult to deal with than any other BA I've worked on. Just ungodly heavy and difficult to move around on the bench. Like all the rest of them. Once I realized I didn't have to remove the front panel to replace the dial glass it was fairly easy to do. Nothing especially difficult about replacing the antenna connector assembly. Just a little patience needed to route the thick coax cable out and then back in through the chassis hole.

    4007s.jpg riteaidedSS.jpg


    One of the few advantages of becoming an old buzzard aged curmudgeon is you start to amass a collection of empty plastic prescription bottles. Here's my "Rite-Aided" SS replacement unit using 4007's. The 5Z4 Pin-2 filament connection wire can be removed and taped up as Glen says. The Pin-8 wire connects to the filter choke L301 wire right at Pin-7 on the LV transformer. I lifted both wires off the transformer, soldered them together and shrink wrapped them for now. Ideally I'll get around to putting a standoff for them in there somewhere.

    Again, nothing particularly difficult about getting a pair of dikes and a fat soldering inside under the 5Z4 socket. I powered it up on the Variac at 115V and got 275V on the LV meter, 50 watts into the dummy load and a reasonable sounding CW signal on the R-390 across the room. So far so good.
     
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