Hmm, why Analag went with 10k and 10uF? I wonder
Interesting... Maybe because it works. How good though I've yet to hear for myself.
BUT if we're trying to copy a Fairchild... why not go all the way & use the original time constants & values?
The question is... will it work correctly on the PM version?
I don't know enough about it to dive into it without asking.

Also,
That's great info about the METER's!!!
I got some "old school" meters that are pretty heavy duty & cool looking but I think they MAY be too beefy for the PM670.

They were originally labeled - one for 100 VDC & the other 100 mA.
I tried removing the resistor inside & put the diodes on them JUST to see how they'd respond as "AC" VU's & the needle hardly moved at all... compared to ALL my other AC VU's like Modutec, etc...
What "resistance" should I be getting for the PM670 to work correctly???
May be time to look for other meters... but I'd like to get these to work.