Update: 6/11/2024
Another project: I restored an ancient Heathkit O-8 scope. The design is based upon a 5CP1 CRT as used in various WWII Military radars and IFF sets; the tube was introduced by Tung Sol in 1944.
The Scope kit was built in 1952, still has all original parts and manual ! Heath apparently bought a ton of surplus military electronic parts after WWII, including a bunch of 5CP1 tubes. I understand their first or second electronic kit was a 5″ scope, the O-8 came sometime later. Still needs some additional cleaning – and then there’s those waxed-paper capacitors that look suspicious.
A guy gave this to me about 30 years ago and it had been sitting underneath a leaking can of black paint which trashed the cabinet and front panel – so it sat in the garage waiting 30 years for a clean-up and smoke test. Pretty crude by today’s standards (hell, I am too !) but it still works! There is something about a glowing green phosphor and a red jeweled # 47 pilot lamp….and the smell of hot dust….It’s looking at a 10 KC “RF” signal from my URM-25…
The Heathkit O-8 Oscilloscope. The sweep linearity needs some work and the Sync selector slide switch is frozen in place but it does still work. The original builder of this scope bought the Heathkit C-08 Conversion Kit as an after market upgrade. (This included some improvements made in the Heath O-9 Scope kit.) The Conversion Kit consisted of the addition of an OA2 and OB2 voltage regulator tubes to regulate the B+ to the vertical amp and the horizontal sweep sawtooth generator. It also included some component changes to improve the bandwidth of the scope.
Update: I found the schematic for the CO-8 modification kit:
Heathkit CO-8 Conversion Schematic
The builder mounted the voltage regulators but did not connect them for some reason! He also did not install the changed components. Wonder why. So I connected the VR tubes; they do the job. The component changes are yet to be done. Fun little project to restore a classic piece of test equipment from the early 1950’s. Plus, it looks cool just sitting there sweeping away….
I built a Heathkit O-8(?) for my high school physics class (c. 1952) using a big, clumsy soldering iron heated over a flame. Gave it to my physics teacher. To this day do not know if it ever worked. Later bought and built an O-10 for my personal use. Used and enjoyed it for many years. Eventually made the mistake of giving it away; now wish I hadn’t.
I believe an oscilloscope was the first Heathkit marketed. Heath had bought a bunch of WWII surplus crts (5CP1?) and oscilloscope power transformers, and these were the basis of their first scopes. They continued to market a low-cost scope until this supply was used up, even though at the same time they also sold more capable scopes.
I envy you your O-8. Enjoy!
John, no8v
Hi John – Yep, I think you are right about Heath’s first electronics kits and the use of surplus parts. I think their actual first kit was a kit aircraft! I think Heath taught a lot of us a lot of useful stuff over the years….
Seems my scope has a CRT issue. I discovered that the Horiz sweep plates are probably loose or mispositioned. Equal voltage on each H plate does not center the beam. Gotta find a “new” CRT !
Thanks for visiting the site!
73, Tim
Tim,
I think you’re right about the Heath aircraft. I believe it was called the Parasol (sp?). I, too, grew up building dozens of Heathkits…and still have several. Also built some Eico kits (stereo stuff). Remember them?
Thanks for your site,
Randy S. from MIUW 13 in the 70’s & 80’s (Pre 104)
Hi Randy – Yep, I think that’s what it was called…He was an interesting guy. He bought a lot of surplus parts and that started the electronic kit business, pretty good gig…I build 8-9 Heathkits over the years and I felt it was good equipment, still have a lot of it…
MIUW13! Nice! We had a MIUW 103-104 meeting yesterday in Oakland, planning an annual reunion picnic at Coast Guard Island in the Spring if you are still in the area. Stop by!
Tim
Tim, I am surprized that thing worked when fired up with the original paper caps, I have an O-8 too and plan to restore it. I wanted to let you know that the first Heathkit kit was the Heathkit 5, oscilloscope in 1947 and was called the “5” because of the 5 inch surplus CRT. There is restored one of the first 100 that were made on display at the Antique Wireless Museum in Bloomfield N.Y.
Here is a great webpage with information on this first Heathkit kit;
http://www.ohio.edu/people/postr/bapix/HLegacy.htm
73, Tom, K2BEW
Hi Tom – Glad you checked in….I was a bit surprised too – but I figured if any of them were going to fail upon startup, they would identify themselves for me.. However, it it still running fine, no failures. I think Fair Radio had (has) replacement NIB CRT’s so I probably should order one, this one has a strange, although understandable problem with the H Plates position. Was probably dropped sometime in its past.
That’s an interesting Heathkit link – Thanks! Heathkit’s are a big part of my early interest in electronics, science and engineering and the ones that I built are still working. Especially fond of the CR-1 Crystal Radio my Dad built for me when I was in the 5th grade. It still works great – good memories.
Thanks for visiting my website & 73,
Tim
I had that model in 1973.. the 2av3 hv rectifier was problematic.. the heater was heavily isolated and the focus potentiometer was too small so it started to overheat after 20 minutes.. but I think you would just replace it with 4 “1N4007” silicon diodes in series.. and that would reduce it’s power consumption by 5 watts. The high voltage coming out of that 60htz line transformer is on that first potentiometer at the top right on the intensity control.. and it bites. After you solve that problem , you can just use 12at7’s or 12aX7’S OR 12AU7’S. I drew a schematic for that thing by hand in case it stopped working, took a week.. that scope was the most interesting thing I had ever seen, and it was 30 years old when I had it! [snip].
It is almost a decade after your post… March of 2019, and guess what… I just scored an ORIGINAL Heathkit 01 oscilloscope for $5 at a local hamfest. Wow… Heath’s FIRST kit! I’ll make it work ala Paul Carlson, a.k.a. Mr. Carlson’s Lab here on YouTube or the deluxe version on Patreon.com.
Wish me luck! ARS KQ2E
Hi Bruce – Yep, time flies! Mr Carlson’s Lab YT channel is very good…I’m a fan…Have fun with your new/old scope!
Thanks for checking in..Tim
I have just purchased one of those Heathkit 0 – 8 oscilloscopes. Do you have any information on that c – 08 addition like schematics or anything I have the schematic for 08 and 09 but they don’t include that little add-on if you have that information I would greatly appreciate it.
Hi Zach – When I first started looking at this scope I had found the schematic for the conversion kit online – but I can’t find it now. If you have the schematic for the O-9 scope it probably includes those changes, notably the 2 VR tubes. The conversion circuit is probably still online someplace, there are many Heathkit websites to try…
Tim