- 2024
- Nov
- 23
The B&W Model 200 Signal Generator
This is a device I picked up at the Dayton Hamvention earlier this year (2024.) It wasn’t much, but what caught my eye is that the thing is built like a brick shithouse. The big dial on the front is just wonderful in it’s smooth spinning. It’s missing a single output terminal cover, but that’s not a big deal.
This looks to be similar to most generators of the era, with a couple of extra tubes. I’m going to assume that since this has a balanced output, it’s using a phase inverter and final amp to drive the transformer output. Otherwise, it’s your standard oscillator and that old GE lamp as a PTC resistor, just like you’d find in a Heathkit or other type.
Tube compliment is:
6X5 as the rectifier
6SN7 as the final drive amp
6SN7 as a phase inverter
6SJ7 as the oscillator
GE3S6/5 lamp as a PTC resistor in the oscillator
(I assume)
The bottom is fairly clean. Some capacitors probably need to be replaced…
But a quick check says maybe no?
Output looks ok…
But about 3-4 minutes later the signal starts falling off, as in just fading to zero - and them coming back up. It just keeps doing this over and over, no matter what the output level or frequency is. I’m not sure what’s going on here, but the signal comes back up like the oscillator tube is dying.
I’m not sure what’s going on here, so I’ve picked up a new 6SJ7 and a couple of checked good 6SN7 to sub out and see if it’s one of the those. I have a used lamp laying around somewhere and I’ll check that as well. Other than that, I haven’t really investigated things much as data about this unit seems to be kind of scarce.
Stay tuned and we’ll see if this thing works!
Next part of this series: https://wereboar.com … or-part-2-diagnosis/