Continuing my effort to improve my workbench and its test gear, this week I turned to an old frequency counter that I picked up at the Kempton Park Radio Rally in London many years ago. It was not working when I got it, but long-time SolderSmoke listeners will recall the tale of woe that resulted from my having soldered a replacement IC (that Tony Fishpool G4WIF had sent me) UPSIDE down. Tough times my friends, tough times.
Well, I'm working on it again. First I converted it from 220 to 110 power. I had a transformer in the junk box that fit nicely, both electrically and mechanically. In the course of doing this, I learned something about this counter that I did not know: As long as it is plugged in, even if you turn it off, the time-base oscillator keeps running. And get this Color Burst Liberation Army members: The oscillator runs at 3.579545 MHz. TRGHS.
With sunspots scarce and with Pete pessimistic about the solar cycle, VHF and UHF now seem more interesting. I need to have more test gear for the higher frequencies. This counter works up to 650 MHz. Yea!
When I first fixed this thing, I was quite pleased to get it going with "Input A -- 5 Hz to 100 MHz." But now I want to get "Input B -- 40 MHz to 650 MHz" working also. I used a 50 MHz signal from my newly repaired HP-8640B to trouble shoot Input B. I think one of the divider chips is bad. It is a Plessey SP 8630B. Does anyone have one of these chips in their junk box?
Available from a reasonably good supplier on ebay https://www.ebay.co.uk/itm/202315641935
ReplyDeleteHowever the pricing is a mugging. Or is it? The IC probably cost more when it was new.
Hi Bill,
ReplyDeleteanother ebay source (well hidden, but from KY this time): 381676125585
Maybe OM Jeff WA#ZKR can help out.
73s Joh
The ebay.uk is pricey and I doubt the chip was that much new. You may be able to look at the schematic and find a similar ECL chip that you can substitute with not too much effort if other potential sources cannot help.
ReplyDeleteYou mentioned going to a qrp gathering in the last podcast, but, looking at the ARRL/TAPR Convention mentioned, did you know that a group with a similar name has a 9600 baud modem project TNC ? Its really affordable and cool. About $30 for everything! You get the board from "tarpn" which is actually Terrestrial Amateur Radio Packet Network , plus the microprocessor pre programmed. Then you order the rest of the parts with a shopping cart macro, and believe me, even though it seems like it won't work, it does, at DIGI-KEY ! Something like 22 dollars more. FOLLOW THE EXCELLENT INSTRUCTIONS, don't think you can fly through it without at least seeing the tips in the instructions, it will save you a ton of time. If everyone were to switch to 9600 with APRS and Packet, I'm sure there would be a revival. Check it out , took you right to the meat of the project, the ordering and assembly page. http://tarpn.net/t/nino-tnc/n9600a/n9600a2/n9600a2-assembly.html
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