[Test-Equipment] HP 8640B Fuse Question

[Steve]

At 10:34 PM 2/3/2015, Barry wrote:
>Also, I'm not seeing the little finger-style switches and, instead, 
>just ordinary rotary switches.  Did the early models have a 
>different switching system from the later ones?

I also have one with rotary switches as well as one with the damb 
plastic disks with "falloffem" fingers. I don't remember which had a 
later S/N, though.

As for the fuse question, I dunno. I now have to use the rotary 
switch one since the fingers felloffem and I couldn't find them all. 
When you do find them all, however, they can be superglued on but I 
believe I already did that to that one so mebbe more fingers 
felloffem or maybe the same ones felloffem. In either case, I was 
very disappointed as that was the one I had to replace the amplifier 
in, and it also has the 1 GHz doubler. I think I should be able to 
move both over to this rotary one, though. I now never, EVER switch 
the attenuator in the 0 to 10 dB range without turning the RF off 
first. IIRC, when you lose fingers in the attenuator, the amp can 
look at an infinite SWR and that may kill the amp. IIRC, I replaced 
the amp with a pair of paralleled MAV-11s because I either cudn't 
find the original HP amp, or it was too expensive, one or the other, 
and the output is down a cupla dB but still over +10 dBm at 1024 MHz. 
IIRC, but it's been many a year since I've fired that one up.

SteveH K0XP 



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