I had an "interesting" afternoon. First I made the extender (including running coax for the other pins even though it looks like you're right and the 3S2 doesn't use them). Then I slipped while measur

I took a look at the schematic of the 561A. It appears that only pins 3/4 and 18/19 use coax to carry fast signals (trigger to timebase, strobe to sampling plug-in). Still wondering what the deflectio

Since I'm going to be working on this 3T77A plug-in for a while, an extender is necessary. Some years ago I acquired a pair of Amphenol connectors with the intention of building my own extender, but n

Down the rabbit hole again... of unobtainium tunnel diodes, that is. I couldn't get my "new" 3T77A to trigger at all. I'm actually not sure if the 3S2/3T77A/561A combo allows internal triggering or no

Turns out the 3T77A change information (which is considerable) is part of the online 3T77 manual. So I'm good there. The white specks on the outside of the capacitor sleeves wipe off with alcohol and

Does anyone know where I can download a copy of a 3T77A (not 3T77) manual? Also, any idea as to what could cause this kind of mold/mildew on only the axial electrolytic caps, and no other components?

It appears that Deane Kidd's parts inventory is *still* in limbo :( So, does anyone have a new (or good used) carrying handle for my 564, and one of those tiny push-on lever switch knobs for a 3B3? Th

I once tried to order some items from Grainger and actually HAD a small business incorporated at the time... but I abbreviated the name of the company and they rejected my order, saying they couldn't

The best hint for easy-outs (two lies in one) is not to use them at all. I have never found a screw or bolt that was stuck hard enough to break off, that also wouldn't break the easy-out when steady t

I have a 7403N mainframe which I like for its large bright CRT. But the plastic strips that contribute spring tension to the backplane connector contacts are in bad shape, so they don't make reliable

Thanks for the tip. There are indeed several conversations on various "Mods", but I could only find two brief explanations (one in '14 , and one in '13) both by Glenn Little. He did say last year that

My 453 scope is labeled Mod 703H. I haven't found anything online about what exactly the modification consists of, or what it does... Can someone point me in the right direction? thanks.

I did, but "untested" always worries me. I don't need another project right now, I need the scope to be functional ;) Would this one work in my 7403? Tektronix 7B85 Delaying Time Base Oscilloscope Plu

The 7B53N timebase plugin from my 7403 scope has finally crapped out... the sweep range switch has been getting flakier and won't sweep at all sometimes on most of the ranges. I don't feel like fixing

I built a dummy load from ten ordinary 470 ohm, 10W wirewound resistors that works quite well on HF. The square "sand"-cased resistors are mounted in a "star" with a copper foil ribbon connecting the

I have a working RM561A scope which has an extremely noisy muffin fan. Reminiscent of a vacuum cleaner, airplane running up, etc. I think the bearings/bushings are just worn out, since newer fans are

Anyone know where I can find a service manual (or at least a schematic) for a Beckman Industrial FC130A (1.3 GHz counter)? I've checked the usual sources... nothing coming up. thanks Charles

Sorry, that won't work, because if the bulb illuminates you will not see a 7904!

Years ago I resurrected a "parts" 661/4S1/5T3 bought cheap from Mendelson's in Dayton. I eventually sold it, along with two complete cathode follower probe sets, because I wasn't using it... But every

I need a faster mainframe than my 7403N (50-60 MHz), previously used with a 7A18, now that I have 200 MHz bandwidth capability from my "new" 7A26. But I really like the large display of the 7403. Is t