[Boatanchors] HT-32

Robert Nickels ranickel at comcast.net
Fri May 24 10:42:30 EDT 2019


On 5/24/2019 12:26 AM, RAY FRIESS wrote:
> I'm feeling a bit intimidated by my recently acquired HT32.

Ray, let me offer a suggestion that might avoid some real heartache.  
Follow the advice of my friend W8UT and solid-state the power supply 
right away.   Here are some details: http://www.boatanchors.org/HT37.htm

All the comments about HT-37 applies to the HT-32 as well.   The power 
transformer in these transmitters have a long history of failure, and 
converting to solid state rectifiers will allow you to disconnect the 5V 
rectifier filament windings completely (clip them at the socket) which 
will eliminate one of the common failure points - shorts from HV to 
filament windings.

I also suggest adding an inrush current limiter which will provide a 
"soft start" and further reduce stress on the transformer.   The 
Thermometrics line is now owned by Amphenol Advanced Sensors, and I 
can't be sure but I probably used the CL-60 which has a cold resistance 
of 10 ohms and can handle a steady-state current of 5 amps.  Mount it in 
open air as it will run warm to hot but it's designed to do so.

And of course replacing the filter caps with new ones will reduce the 
charging current that the transformer must supply.   Doing these things 
to protect the power transformer will give peace of mind - having lost 
two transformers this way,  I love *not* hearing that "thunk" when I 
turn on the power!

73, Bob W9RAN



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