Yes likely a 502. ONE mc bandwidth. No removable plug- one. Roy Morgan K1LKY Western Mass

Have a look at this thread: https://groups.io/g/TekScopes/topic/7642627#44230 Regards Jan Jan Weber via groups.io <jancarlweber@...> schrieb am Mi., 25. Aug. 2021, 23:39:

No, the 7904 PSU is a switching PSU and it needs a minimum load. Regards Jan Reginald Beardsley via groups.io <pulaskite@...> schrieb am Mi., 25. Aug. 2021, 23:35:

This came with a pair of 7A26s and a pair of 7B92As. The seller showed it with a single trace. I have a working 7104, but no significant 7xxx experience. If I plug the 7904 PSU in with no load,

Reginald, Zen is right about the tantalums as the filters. I replaced the ones in my supplies with 47mfd (7704A) and 56mfd 100V Nichion UHE types. I have seen 60 and 70V types in the 50V supplies.

Also check for Tants that might have gone south. Tek ran the tantrum caps close to there max voltage so a failing filter cap can put excess ripple on the supply rail which can push a tant over the

Reginald, The power supply parts can be checked/replaced with it still attached or taken out. For power testing, it must be attached and the case touching the frame or a test lead from the case of

PS Have earlier this evening some pictures of past related projects. Dave

Some folk reading here about gm in mA/V or Transconductance in micromhos, might wonder why folk hand-draw graphs(like this old fool), or rely on a Tek570, or use an excellent modernised/hybridised 576

Hi all tube tracer fans, I just updated the pictures in https://groups.io/g/TekScopes/album?id=267344 The order of the pics is anti-chronological, I cannot seem to get it right. So in chronological

Unpacked, plugged in, turned on and went to get a probe. When I got back I smelled the stink of dying electronics and all the lights on the scope went out. It did *not* blow the fuses and I have not

Martin, loss of Gm indicates the use condition better than loss of plate current. There is no such thing as data sheet value for plate current at a given grid voltage. The number they print, is only

Probably a 502.  My first scope was a 502 (it was also the reason I joined Tekscopes, but I have never gotten around to finishing the repair).  Not only is the bandwidth low, but it varies depending

https://groups.io/g/TekScopes/album?id=131745

I used to have A 500- series scope with dual beams and low bandwidth. Not sure of the number. The bandwidth was low. I remember that the intended application was medical and biological research.

Nice to hear that, Chuck. I just have re-installed my double-576-weight U61. Actually its not the double, I think, but it looks sturdier. Anyhow, I had to wait until competent 3rd and 4th hands were

John, I have posted a photograph of a few R7103s in a rack and ready for an underground test. You will see the same hardware on the bezel. The photo album is named Mighty

Mark, Wow, that is a tight call from such a dark picture. I had a look at the TekWiki page, and while you are obviously right, I would have had a very hard time figuring that out. I'm not at all

Its great to read about other folk's projects. Certainly those relating to valve/tube testing. It also enhances my belief that hybridisation of vintage T/Eq with other vintage items &/or modern

Jeff, Even with the dark photo in the ad, it is a 565 with P2 phosphor. The placement of the knobs below the screen and what writing that can be read were compared to the light pictures of a 565