Heathkit W5M Surgisitor

[ddragg1]

Hello and Happy New Year's eve. I have a question about the surgisitor in my W5M amp. I'm thinking about replacing it with a newer CL-80 thermistor. Would I solder the ends as the surgisitor is soldered? I assume the these aren't polarized? I have a W5M mate coming in this week and will make the same mod on it. Comments and suggestions welcomed.

 

[Buck Rogers]

Yes, That should be fine.

Another advantage of the CL-80 is it will lower the line voltage just a little bit.

These amplifiers were designed for a 117 and run dam hot, My line regularly hits 122 - 124 vac.

 

[nerdorama]

I've done several W5's and I used the equivalent of CL-90. It put the filament and B+ really close for me.

 

[ddragg1]

Thanks a bunch for the information guys. I'll remove the old surgistor and replace with the CL-80. I get my matching one today and will inspect it. Happy holidays.

 

[ddragg1]

All done and playing gloriously. Thanks for the input.

 

[zackthedog]

I'll bet. ;-) Nice speakers, what are they?

 

[nerdorama]

What is your normal line voltage? The CL-90 may be a better option. It's warm resistance will stay a bit higher than the CL-80. The 80 won't drop much voltage when warm. I've use the CL-90 and equivalents of other makes in quite a few tube amps. Even though it is rated at 120 ohm at room temp, it drops down low enough with only about 3/4-1A of line draw. Trial is your only way of really knowing with certainty.

 

[ddragg1]

Zack. The speakers are JBL C36. I did a piano black refurbish to the cabinets about 10 years ago.

 

[ddragg1]

Nerdorama, my line voltage is 121. The cl-80s seem to be doing the job, but I may get a couple of cl-90's and try them out. Really don't want to fry these transformers. Thanks for the input.