HP1725a Trace Anomoly

snipped-for-privacy@gmail.com scribbled thus:

My 1735A doesn't do that ! I think the voltages may be wrong.

tic over it and that is not the problem. It seems the haze is magnified com pared to the trace. See pics :

ely it is to protect the phosphor from the intensification need for the wri ting speed. Could that be it ?

wn, but then when it is in the intensify mode, it is quite visible. (delaye d sweep is another issue for another thread)

ope.

Jurb Can you reverse the deflection plates wiring and see if the problem moves?

I worked for a cal lab/rental company in the early 80's. I remember when we got a load of those brand new HP 1700 series scopes in for rental. They ac tually weren't bad scopes, and from a service standpoint, compared to a 400 series Tek, working on them was a walk in the park.

The problem was that most Techs who grew up playing with Teks were not will ing to switch. As illogical as this was I have to include myself in this gr oup. This really hurt HP. Like many other guys, I was and still am a die ha rd Tek man.

I still have my 561B which I pulled out of a snow covered scrap pile outsid e of a GE plant. It had been junked for poor phosphor storage performance. Well phosphor storage always sucked anyway and the scope, in standard displ ay mode was just fine.

The old girl treated me well for many years. I've since upgraded to a 453 b ut the old horse still sits in a corner of the shop still with it's little roll of silver solder inside. I just can't seem to part with it. Lenny

You chopped off the right side of the scope front panel, so I can't see the position of the sweep controls. My guess(tm) is that you have it setup for delayed trigger, with identical sweep times for both the sweep and the intensified delayed sweep. In that position, the entire trace is intensified. Try turning off delayed sweep and/or trigger.

I know how to use a scope. This abberation eeiss a all scales, time or voltage.

It is as if it is projected onto a sendary sreen beyond the phosphor. I have been in alot of CRT technology in my life and never seen this. It is as if the beam can project something through ana angle.

Very coincidentlly, I notice a video in which a guy cut teeel, THICK STEEL with a torch, ON AN ANGLE. That means using the torch like a mitre saw.

Within a year, we shopuld be able to cut you something.

Damn I f***ed that up.

Anyway, the sweep was set to main.

That's the way we usuually use them...

First of all I do appreciate all your reponses, especialy from such a group .

Those voltages are only routed through the gate board, not modified at all, as far as the print is concerned.

? "

Yes Mon Cpaitain, but... It might not prove anyhting. I can reverse the H p lates but not the V plates.

The reason for this is because the V plates are consideed a wavguide. (this answers a question posed here in another thread)HP runs the output of the collectors into one end of the plates, and feeds their bias to the other en ds. Apparently they had to do this to achieve 275 Mhz bandwidth.

I guess I undersatand why, when trying to control a stream of electrons in a vecuum, it might be different than riding a bike.

There is also that delay sweep problem...