Heathkit IO-4105 5mhz Oscilloscope - Page 1
Forum section: electronics / testgear

author: queennikki1972
author_rank: Regular Contributor
timestamp: September 10, 2019, 01:22:17 am
content: So I ended up with a old Heathkit IO-4105 5mhz Oscilloscope. HUGE THING BY THE WAY...I plan on purchasing a brand new digital scope around October, but I though this one would be good to learn with..I found the manuals but before I can test anything I need to buy a probe. What probes are best for this old machine? Any BNC 1x probe?Nikki

author: Stray Electron
author_rank: Super Contributor
timestamp: September 10, 2019, 01:43:21 am
content: I don't know. But even if it's the wrong probe you should be able to learn a lot with it, starting with how the probe distorts the waveform.It's possible to learn more from your failures than from your successes.

author: edavid
author_rank: Super Contributor
timestamp: September 10, 2019, 02:04:16 am
content: Even though it's only 5MHz, I'd still get a switchable 10X/1X probe.

author: med6753
author_rank: Super Contributor
timestamp: September 10, 2019, 10:24:30 am
content: It has a standard input impedance of 1MEG so basically any x1/x10 probe will work. Many of the older Heathkits had an input impedance of 3.3MEG which required a special probe.One thing you will notice which can be an annoyance is that the scope is in an unshielded plastic case and the CRT has partial shielding on the gun assembly only. Depending upon how you position the scope the trace may be tilted due to the earth's magnetic field. And there is no trace rotation to compensate for it.

author: queennikki1972
author_rank: Regular Contributor
timestamp: September 10, 2019, 12:33:54 pm
content: There is a very slight tilt but nothing major. I was wondering about that myself.Quote from: med6753 on September 10, 2019, 10:24:30 am

author: Cubdriver
author_rank: Unknown
timestamp: September 10, 2019, 03:39:25 pm
content: That looks very similar to the Heath IO-4541 scope I built as a kid. Their answer to trace rotation was CRT rotation - the gist of the instructions in the manual for trace alignment was basically, "loosen the hardware that holds the CRT and carefully rotate it until the trace is parallel to the graticule". If it's not too bad I'd ignore it; if it bothers you you'll need to open the case, then loosen the CRT and align it. They are big old monsters size-wise, aren't they?-Pat

author: med6753
author_rank: Super Contributor
timestamp: September 10, 2019, 05:08:54 pm
content: Quote from: Cubdriver on September 10, 2019, 03:39:25 pmYep, that's fine....until you move the scope to another location and the trace is titled again. I built one too....a long, long time ago.

author: Cubdriver
author_rank: Unknown
timestamp: September 10, 2019, 06:59:00 pm
content: Quote from: med6753 on September 10, 2019, 05:08:54 pmOr until, as you're putting it back into the case, the graticule shifts.-Pat

author: med6753
author_rank: Super Contributor
timestamp: September 10, 2019, 07:22:21 pm
content: Quote from: Cubdriver on September 10, 2019, 06:59:00 pmYep, that too!

author: queennikki1972
author_rank: Regular Contributor
timestamp: September 11, 2019, 07:58:02 pm
content: Quote from: Cubdriver on September 10, 2019, 03:39:25 pmYes

author: queennikki1972
author_rank: Regular Contributor
timestamp: September 11, 2019, 08:51:04 pm
content: On the front bottom right I have a banana jack labeled 1V (P-P) 60Hz. I know from the original documentation that this is 1 volt peak to peak 60Hz for calibration and Testing. My question is this. It is not a clip on like the new modern oscilloscopes have rather the banana jack. So how do i connect my modern 10x probe to this banana jack and will i need to connect to the ground banana jack as well. I know the original probes were like alligator clips or something. Should I make a homemade wire harness that i can clip to or do they already make this...?

author: queennikki1972
author_rank: Regular Contributor
timestamp: September 11, 2019, 08:56:20 pm
content: Never mind I found a way to do it..

author: GerryR
author_rank: Frequent Contributor
timestamp: September 11, 2019, 11:13:41 pm
content: Quote from: edavid on September 10, 2019, 02:04:16 amIf you get probes (1X-10X switchable) that are good for the bandwidth of the scope you are planning on getting in the future, you will be able to use them for both 'scopes.