Re: {Collins} 32S-3 power output problem sort of resolved



Hello again Grayson,

Glad you're making progress and also that the suggestion re a PSU check etc bore some fruit.  

I think you're getting very close but, as a point of comparison my '68 vintage RE 32S-3, currently running on a stock 516F-2 (tube rectifiers) and using 6146Bs, checks out with the numbers I recalled in the last email: more than 100W on the low bands and 90W on 10m.  When I throttle it back for the reasons noted b y Glenn, it's close to the book value of 100W and 80W for 80m and 10m, respectively.  This is all with a whisker less than 120V line voltage.

As far as the PA tubes go, I believe that if you have an air neutralization capacitor and the PA neutralizes correctly, you're fine with the 6146Bs.

I've had a few interesting times of my own recently flowing from the rather poorly converted 516F-2 which I got with my 32S-3.  Without boring you, the HT failed in a fairly dramatic fashion but, fortunately, there was no transmitter damage.  I've substituted the tube 516F-2 mentioned above, having previously overhauled it as a spare and added a mains power switching relay.  The other 516F-2 is now back on deck as a hot spare, having gained a Radio Farm conversion board and a new L3 from KE9PQ.  For some reason part of the previous poor conversion had replaced L3 with a smaller unit, and added a Hammond filament transformer, despite the Collins transformer being in good shape.  The pity of it is that it's quite a late serial number PSU, ill deserving the treatment it got at unknown hands!

While your HHT is still officially just within the Collins spec for the 516F-2, it wouldn't hurt to try a new rectifier tube.  What is the LHT measuring loaded and unloaded?  For reference, mine is right on 300V with the transmitter idling.

73, Peter (VK6HP).



-----Original Message-----
From: Collins <collins-bounces+p.hall=curtin.edu.au@xxxxxxxxxxxxx> On Behalf Of Grayson Evans via Collins
Sent: Sunday, 12 May 2019 8:31 AM
To: <collins@xxxxxxxxxxxxx> <collins@xxxxxxxxxxxxx>
Subject: {Collins} 32S-3 power output problem sort of resolved

I posted a problem I was having with my 32S-3 restoration project earlier in the week.  I had really low output on all bands, but much worse on the high bands.  Got a lot a good advice on probable causes, mostly suspecting a poor set of 6146’s.  

It turns out there were several problems.  A pair of 6146B’s came with the unit when I purchased it about 20 years ago when (yes, it has taken ma a LONG time to get to it).   They were weak.  When I dug into my tube boxes I found a lot of 6146’s I collected over the years,  4  JAN NOS 6146W’s (88 date code), 4 RCA 6146B’s (64 date code)

But the real problem was the power supply.  It was a bench supply I built years ago for testing and troubleshooting 32 series transmitters.   Really poor output.  I replaced it with a stock 512F-2.  More power!

The next problem was the power meter.  I was using a Heath HM-102.  Took that out and measured power directly at the dummy load with a scope probe and did my own power calculations.   The HM-102 was only accurate on 40 meters.  

OK, so this is what I have now.   Again would like your opinion if this is good or I need more troubleshooting.


I have very good grid drive on all bands.  
I did all measurements with the tuning and loading set for 230 mA on all bands.
The 512F-2 is “stock” with tube rectifiers.  Only the filter caps have been changed. 
The 512F-2 high voltage looks like this:   880V idle,  720V  LOCK KEY.   Primary set at 115V AC.  (a voltage drop of 160 volts.  looks like a lot to me)

                   6146B    6146W
              -----------------------------
3.7 MHz     100W       100W
7.1 MHz      95W          85W
14.1 MHz    76W          90W
21.2 MHz     65W         65W
28.1 MHz     65W         56W

I can’t explain the fluctuations in the output power between the 40 meter and 20 meter bands.  I tried the tuning twice and got the same results.  Weird.  

Seems to me I read something about the 6146B’s not working out in the 32S series, so I’m going with the 6146W’s for now.

Grayson, KJ7UM

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