Re: Heathkit HO-10


With a few mods, the HO-10 makes a good monitor scope.

Stock, it sucks.  Too much hum in the trace, both vertical and Z-axis (brightness) are 60~ hum modulated.  I had to reroute the filament line, and replace that little piece of tin can stock wrapped around the neck of the scope tube, with a real electromagnetic CRT shield salvaged from some piece of surplus gear.  I also beefed up the filtering in the HV power supply.

I don't use the vertical amplifier, but couple the rf directly to the crt deflection plate.  So I pulled out the tube in the vertical amplifier, and the slopbucket two-tone generator.  Less load on the power supply, and now have that extra compactron as a spare.

If the compactron ever becomes unobtainium, each internal section is equivalent to a 6C4 or 12AU7.  I once had it figured out exactly how I would make the conversion, but that was years ago, and I have since collected a couple of spares.

Mine eventually crapped out a power transformer.  I have heard that is a very common problem.  I found a parts junker at a hamfest with a good xfmr and got my modified one going again.

Regarding the hum, it is due to poor design, and Heath admits as much in the assembly manual.  They state that hum in the trace is normal, but should be not make the scope "less useful" as a modulation monitor scope.

IIRC, I also modified the CRT focus circuitry to add astigmatism control, to get a cleaner, finer trace.

Just easier to use a $5 hamfest scope....

Pete, WA2CWA:
If one is using the Apache/Mohawk/SB-10 combo, the HO-10/-13 cabinet and front panel colors will match the rest of the rigs. "The Heathkit Look"


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