[Milsurplus] URM-25D Questions

[Kenneth G. Gordon]

On 27 May 2017 at 17:22, Joe Connor via Milsurplus wrote:

> 
>     I just picked up a URM-25D signal generator at a hamfest today, and I have a 
> few questions:
> 
>     1. The three filter caps are 4 mfd. at 600 WVDC. Is 600V necessary or is it 
> excessive headroom? The closest I can find from the usual parts sources is 8 or 
> 10 mfd at 600V.

The only critical parameter in such capacitances is the working voltage. Capacitance is not 
critical, although in my experience, the more (within reason) the better. I'd use the 10 mfd.

>     2. How reliable are the other caps in these units? Should I replace them as a 
> matter of course?

I have a URM-25F. By now, all the internal caps except the micas have to be replaced. Mine 
keeps eating 6X4s.

>     3. What's the name of the connector to hook up to the output jack? (This may 
> be where I'm going to really miss Radio Shack and their supply of connectors).

Don't remember that one. I'll have to go look. BTW, Fair Radio Sales still has collections of 
the varous connectors which originally came with those sig gens. But you have ask for them. 
They are not in their catalogs.

>     4. The old Hollow State Newsletter had a few articles on these units. Is there 
> an on-line archive for this publication?

I think there is, but in any case, I have a complete collection of those and will send you copies 
of the appropriate ones as long as you can tell me which those are. I can't look through them 
right now.

>     5. Any other tips or advice?

They are an excellent sig gen. You can connect a frequency counter to the high-level output 
jack (BNC, I think) for constant monitoring of the output frequency.

Until mine crapped out (I have to replace caps, but have not yet done that) I regarded it 
highly. In fact, I felt it was more reliable than my HP-8640B, although more difficult to use.

Ken W7EKB

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