[Milsurplus] ARC-38 chopper issues

[J. Forster]

What is failing? The coils or the contacts? If you drive the thing w/ an
audio oscillator, can you feel it vibrate? Are there 1 or 2 driver coils?

If it's the contacts, running it for a while and switching some current
through it, might clean the contacts.

Is it a stock part W/ a MFGrs name & number?

Best,
-John

================



> I have spent much time getting my ARC-38 running, many hours have been
> spent cleaning and lubricating all the servo motors, bushings and rollers.
> Now the band switching, rack tuning and PA all work correctly and
> automatically. The companion 180L3 antenna tuner is still getting worked
> over, the chopper that feeds the servo amplifier has an issue. Think I
> have another bad chopper. The last radio I did was a 618S1 that is a 144
> channel crystal control version of the 38 that had two servo systems. One
> tuned the slug rack and one for the PA deck and both choppers worked with
> no issues but on the ARC-38 both servo amplifier choppers were bad along
> with the third chopper in the correction amplifier for the SMO. Luckily I
> have an ARC-38A chassis that I have been striping for parts but now am out
> of spare choppers. The question is where the 400 cycle choppers a high
> failure rate item in normal service? The one in the 180L3 also appears to
> be bad. If you beat it with a screwdriver it w
>  ill work for a while but then die again, looking at the chopper in the
> 180L it looks a little different than the ones in the radios but is it
> the same? The 180L3 I have paired with the 618S1 has a dead
> autotransformer so I disabled the servo systems in that and used it as a
> SWR meter and T/R relay for that radio but I wanted to have the fully
> working 180L with the ARC-38 but the chopper in the dead 180 appears to
> be just as bad. So do I need to start building up a supply of 400 cycle
> choppers or is this just an anomaly? Fair radio has several dead 38A
> chassis in their back room and wonder if I can buy all the choppers out
> of them?
> Ray Fantini KA3EKH
>
>
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