The AM Forum

I have two J38-5245L Frequency counters. Both late 1960's vintage boat anchors.
 
Front panels are Marked Western electric KS-19714-L1
 
Both are made by HP for WeCo. They are both a Western Electric variant of HP 5245L Counter
 
One is sn 544-07029.
One is sn 716-16691
 
Both have odd ball or modified time base oscillators that differ from “stock HP” 5245L’s, and they have no external time base input provision on the rear panel.
 
 
I want to make some mods, but looking for some documentation. Any ideas? Web search had zero results. Anyone with access to KS files?

 
Tnx,

Hello Seth,

Here is a link to the service manual, including schematics.  They are separate pages that may need to be linked together to be usable, they were fold-outs in the original prints.

http://www.kennethkuhn.com/hpmuseum/scans/hp5245l.pdf

I have three HP 5245L counters, working fine with various plug-ins, they are fine instruments.  I have several incomplete units for part supply, and may be able to assist you with your modifications.  Let me know your goals and progess.

Good luck on your project!   Rick

I checked some of the Bell System historical sites that gathered documentation over the years but very little in the way of WECo KS information. Back in the "good old days" many of these "KS" documents were available from the Bell Labs and WECo libraries, but when these locations were being shut down, most of that stuff was discarded to document recycling. You might poke around and see if there's a HP forum for old test equipment. Maybe some one might have some info.

Seth,

Check your PMs, and let me know.

Mike.

Not many people into collecting or restoring vintage frequency counters! I have a FR-38 that I did a year or two back but have no real use for it, just remember as a kid hanging out on the MARS station at Dover AFB and they had one there and at the time thought it was the most amazing thing in the world.
Have a video of it at:

https://www.youtube.com/watch?v=3ka1wwvex5o

I've had 5245s of one flavor or another for years, and for the last decade or so I've had this 5245M.   These are great counters, and with three plug-ins, you have a universal counter that will measure pulses down to 100nS, count directly up to 18Gigs, or give accurate readings at sub one milli-Volt input levels.

They're old, cheap, and nearly impossible to kill.


HERE (https://mikeharrison.smugmug.com/TEST-EQUIPMENT/HEWLET-PACKARD/HP-5245/i-gdMMcRc/A).. are some pics of the counter and plug-ins.

Timing instruments, time and frequency is always fascinating.
I've saved a few of those 'neon decade' types over the years. None are working.. just kept from the trash. Recently saved an H/P clock found at an estate; 3 pcs. the 113BR + 104AR + 724BR. Never saw one of those working.

HP clock wud be neat. I plan to use either a GPS disciplined clock for my 5245L or a Rubidium source, divided down from 10 MHz down to 1 MHz for the 1 MHz external input. ST

I love my 5245L (except when I need to move it. They are HEAVY). Also have the 50-500 MHz and .15-3 GHz plugins, and the DVM plugin too.

When I got it, the crystal oven was fried (probably why so many have had their oscillator replaced with a more modern TCXO). It is powered whenever the line cord is plugged in. Lots of burnt heating element and charred foam fell out when I disassembled the oven.

I too removed the original oven & crystal and replaced it with a surplus 10 MHz TCXO supplied by a LM323K regulator, which also stays powered all the time. Some "time nuts" (there's actually a forum by that name) will use a GPS-disciplined oscillator, or even a Rb or Cs standard. I don't need quite that much accuracy  8)

I bought a GPS time base 5 years ago.   It's certainly more than accurate enough for anything I do.   It was just another one of those impulse "gotta have" items, but it's nice to know I'm "on the right cycle". ;D

All the old counters are investments! They can only increase in value over time.