[R-390] 8640B

[wa4aos at aol.com]

 Hi Group,

I have 4) 8640B's in my electronics lab and use them often. I have them set up on various benches and that makes service, burn-in and evaluation all possible with minimal moving units around. I bought two of the from George Bojr in Texas and he has repaired another one for me. He has parts for the 8640B and does a GREAT job with service. The turn around was quick and I was very pleased. You can find them cheaper on ebay but understand you may get a dud and or one with split gears and other issues. George can not give you a NIST sticker but his equipment is calibrated and all of my units are dead on between units. He does sell on ebay but may have inventory for sale at any given time. 

Personally, I like the 8640B for receiver work. They are accurate, dependable and small compared to older units like the 606A/B..You can also use it's internal counter for external measurements, so, it's really two pieces of equipment, though, I have other counters, 

Typically, I let them warm up half an hour before I do any serious alignments as I would no matter what generator I use.. Like most HP gear, the 8640B accepts and external 10MHz reference input should you care to do that. I bought one of the 10MHz GPS receivers on ebay with antenna for around $150 and build an adequate distribution unit to reference a number of HP items in my lab. You can also find pulled Rubidium clocks with a 10MHz out very cheap now as well, under $100. Nothing like knowing you are dead on accurate.
Keep in mind, the 10 MHz external reference is just something I wanted to have; I have a very bad case of gadget-itus. Hi Hi . 

The 8640B's calibrated are plenty good enough for almost anything you will need for working on HF receivers.

His email address is 
www.gcbojr at aol.com

73,
Glenn Scott WA4AOS
DSM Labs