Heathkit IB-1102 Frequency Counter: History, Restoration, Demonstration, Theory

In this video, I document the successor to one of Heathkit's first digital products, their model IB-1102 frequency counter (their first digital product was the IB-101, and then the IB-1101, which looks identical to this IB-1102 but with a lower frequency range).
I cover the history of this model, the few steps I took to restore it to fully working condition, I demonstrate it in operation, I describe the circuit theory of operation.
Early in May 2024, I will be placing my newly CAD drawn IB-1102 schematic, calibration, etc; document on my fileshare webpage, where it may be downloaded: www.serpentwebsite.com/fileshare.htm
Timeline Table of Contents:
00:00 Introduction & history
05:56 Internal tour & restoration
44:25 Testing & demonstration
52:11 Final assembly
56:14 Beauty shot
56:36 Shelves of vintage Heathkits, etc.
57:21 Heathkit manual
1:18:42 Schematic diagram/circuit theory

[@radioalbany2]

A splendid explanation. In the 70's I'd often think "yeah, yeah, 7490 7476 ... Big deal. But I was often guilty of thinking that recognizing something, like a diff amp, was the same as understanding it. Not so. When you explained, say, the speedup circuitry I learned a bunch of new stuff. Thank you.

[@marcseclecticstuff9497]

A good friend of mine has an 1102. Many years ago he brought it over for some minor repair. I was surprised to see it had a TCXO inside it. While it was on the bench we adjusted the TCXO to match my frequency standard and found the oscillator to be very stable once is settled down. I also threw it on a signal generator and tested the actual bandwidth and sensitivity. I remember being surprised at how well it did although I don't remember what the figures were. He brought it back over quite a few years later to check calibration and it was still pretty much spot on. Absolutely amazing that it was that stable over a number of years. I came away being very impressed with this little counter wishing I had one when I was a boy. Instead I had a B&K 1801 counter that was a complete turd. Decent input sensitivity but the frequency drifted all over the shack. I've upgraded over the years thanks to Fleabay and an industrial surplus place making stupidly expensive gear affordable. I've had a rubidium frequency standard (surplus back when they were $30) and a couple of GPSDO's running for years. I have the 10 Mhz output of one of the GPSDO's running into an old HP distribution amp. All of my gear that has a provision for an external 10 Mhz reference are plugged into that using 10 BNC cables I purchased as a batch to help keep things reasonably phase matched. I even added an external reference input to my lowly B&K 1801 counter so it now has GPSDO accuracy. For simple common stuff you can't beat the simplicity of simply turning it on and it works.

[@ssnoc]

$399 in 1973 is equal to $2,813 today - $399 was very expensive in 73. The average weekly wage was only about $145.00

[@h7qvi]

ECL has lower voltage swings. TTL has higher voltage swing which makes things slow from charging parasitic capacitances.

[@youtuuba]

h7qvi, OK, true and I mentioned the smaller ECL voltage swings. But the fact that ECL's internal transistors are never in saturation is a primary cause of the higher speed. As with most things, there is more than one contributing cause.

[@h7qvi]

@@youtuuba Base-collector schottky diodes keep transistors out of saturation, which I've seen on data sheets of TTL chips

[@youtuuba]

@h7qvi , well, I don't care to debate on this. Everything I said on this topic comes from many sources, databook, textbooks, even the Wikipedia article.