Help: Hallicrafters HT-44, and matching PS..HUM

[WT2W]

Hello fellow boat anchor enthusiast's.   Recently I picked up a nice HT-44 w/PS.  I've had it on CW, it runs full power and loads up nicely into my vertical antenna.  However, as I key the transmitter, I don't need a side tone osc as it has a hum or low level growl..I get good reports...589 etc...what could this be?  I'm not even sure it's a hum...or is it the power supply telling me I have something wrong.?   any advice will sure be appreciated.  thank Jim WT2W

[AC5UP]

During TX the radio draws maximum current from the power supply, which also means the power transformer is generating a larger flux field than it does in RX. If you have a loose screw on a transformer shield or a loose mounting bolt they can make unusual noises, often heard as a low-pitched growl. The same is possible if any part of the PS cover is loose enough to vibrate. You can test the loose cover theory by temporarily putting something on top that's heavy enough to dampen the vibe. There's also the concept of dried out rubber feet on a tabletop that resonates acoustically with the PS chassis. You can test that by temporarily putting a towel under the PS.

Check for loose hardware first. If all OK check for a shorted power diode or leaky / dried out electrolytic(s).

Since you're seeing normal operation from the transmitter a mechanical issue is more likely. (?)

[K8AC]

I wouldn't draw any conclusions from signal reports you've received.  Listen to your own signal on another receiver.  I've heard Cuban stations with a T7 note get straight T9 reports for an hour.  I really don't think people know what that last digit in the RST represents these days.  If you haven't replaced the electrolytics yet, you ought to consider doing so soon.

[AA4PB]

It makes a HUGE difference whether you have AC hum on your transmitted signal or you are just listening to vibration from your power supply as the load is applied. I wouldn't start replacing any components until you really determine that it is affecting your transmitted signal. Component changes aren't likely to fix a mechanical problem unless you happen to accidentally tighten something during the replacement process 

[WT2W]

Thank you fellows for the tips and advise.  Tonight I took the PS apart.  I tightened every nut, bolt and screw in it.  Reassembled with new rubber feet and bingo! the growling is gone!  I have been on the air and I'm getting good reports.  Thanks again!  The boat anchor gang comes thru!  73  JIM WT2W