HP54510A Sweep output

[PaulR]

I want to have a go at aligning an FM radio using a Cossor 1324 which requires a timebase output from the 'scope. I have two 'scopes a Telequipment Serviscope D31 which has a sweep output but also has a very dim image on the screen. The other is an HP54510A which has a good display but I cannot see any way of getting a sweep output from it.

Does anyone know whether it is possible to get such a signal from the HP? I have waded through the user manual but cannot find any reference.

I have only just acquired the Cossor and am only at the stage of reforming the main smoothing caps so far!

Thank you

[MrBungle]

Probably not.

It might be worth using a function generator (or build a ramp generator) as the sweep and triggering the scope on the sync output of that instead.

[Radio Wrangler]

The 54510 doesn't have a sweep as such, it's a digitising oscilloscope and the frequency of sampling sets the time scale.

the rate it reads out of memory onto the screen is completely unrelated to the timescale of the graph presented on the screen.

Does it have an X-Y input mode? if so, that's your only hope, having something else sweep your wobbulator and have the scope digitise it along with the response.

David

[OldTechFan96]

I tried using a Cossor 1324 with an 1981 Hameg 'scope (no external sweep O/P) and was unable to get anywhere with it.

With help from the forum, I was able feed the 'scope's sweep signal into the Cossor via an op amp. Unfortunately, I had no idea if the Cossor was working properly, despite it being setup as per the service manual. It worked as an 88-108MHz generator but I did not seem to sweep. I sold it on eBay for £1!

It might be easier trying to find a contemporary Cossor 1091 or 1039 and pairing it with your 1324.

If you would like the service manual, send me a PM.

[PaulR]

Thank you for the replies everyone.

I did think that the HP probably didn't have any sort of sweep output but I thought it was worth checking with those more experienced than I am. It is actually my son's. He bought it for a project he was doing but then the power supply failed. After replacing innumerable electrolytics it is now working again but has take up residence here. It is rather over spec for the simple things I use it for but is fun to use. For example it shows that my ancient Advance signal generator is remarkably accurate. At 10.7Mhz the only variance is in the second decimal place which I don't think is bad.

I did look into an X-Y setting some years ago and I think it has one. Thinking about it I do already have a ramp generator in the form of the sweep output from the Serviscope.

However, I am going to display my ignorance now. I thought I would need a 'scope that will show a trace of 10.7Mhz which is beyond the Serviscope. I was thinking about this last night and realised, I think, that the 'scope only needs to display the output curve that is the result of a sweep around 10.7Mhz. The sweep itself could be slower than that. If I am right I could use the old 'scope as the display is ok at lower frequencies.

I would be very grateful for a copy of the service manual, Oldtechfan. I will send you a PM. It isn't looking good for the electrolytics unfortunately as I cannot get the leakage below 5mA at 200V.

Thank you

[OldTechFan96]

I've just sent you over the service manual. Thanks to CobaltBlue for scanning it last year!

[Radio Wrangler]

When you're sweeping an IF or a filter, you can either use a scope which can show the signal directly, or you can use a low frequency scope showing the output of a detector.

With a detector you can work in the microwave region with a quite mundane scope, BUT you get a limited dynamic range due to the detector diode turn-on voltage. Also, with detectors, be sure their output filter is fast enough or keep reducing sweep speed until the displayed shape stops changing.

David

[PaulR]

Thank you for the service manual Corin. It will prove to be very useful. I have sent off for some new smoothing caps and have tested the mains transformer which seems ok. The rectifier valve also has good emission according to my valve tester. It won't test the other valves so that will have to wait until I can apply power properly to the unit.

Thank you also for the information David. I have a Cossor FM set whose alignment is good so I can experiment on that if/when I get the alignment generator working.

[Radio Wrangler]

The greatest value comes to when yo sweep the IF and put the scope on the voltage coming from the discriminator.

You can twiddle things for the straightest line in pursuit of the lowest distortion. Though you need to know your sweeper (Hz/volt curve) is linear. Also audio distortion can be lower than is visible. So maybe a distortion meter comes into its own here, but you can make a start with a wide sweep into the discriminator itself and positioning the resonances where calculation in the design phase said they should be.

David

[MotorBikeLes]

Wow, that is an old 'scope. The D31 grew from the original S31, or Serviscope. I think the Y bandwidth is about 3MHz. The tubes (monoaccellerator type) usually last very well, so it could be worth checking around you -EHT circuit. Something less than 2KV I think, so no20KV stuff to over-worry about. Just the -voltage on the tube base.
They were usually full of brown WIMA capacitors. You need to change EVERY one of those if fault finding.
Generally very reliable, but so old and limited in todays scene.
Les.

[PaulR]

Yes it is an oldie not a lot younger than the Cossor itself. My son bought it for me as a Christmas present many years ago. I haven't delved inside it for a while but I probably should once I have the Cossor back together again. I do remember replacing some capacitors but there was also a problem with some small value chokes in the deflection supply. Fortunately I was able to find the break which was at the end of each winding and repair them. It has worked since although rather dim in full daylight. My son has a Fluke bench top multimeter with some Kv probes so I could borrow that to see where the HT is.