Buying and using an oscilloscope

[Bonky]

Hi. Another noobie question...

...I have a sig gen but without modulation functionality. Is it possible to buy another unit (a modulator) that rides piggy-back on my present sig gen?
I ask because if one looks at one of the DIY sig gen kits there are 2 screws on the pcb for an external modulator...?

http://www.ebay.co.uk/itm/DGS-1-signal-g...1055790875

Thanks,

R

[pwdrive]

I think the one in the Ebay link is for FSK mod, if so then no good for what you want if you want it for general radio work.

I would buy a known working old style service type sig gen if you want a sig gen for general radio work, one of those will have mod facilities built in with its own modulator and modulation source.

Lawrence.

[Murphyv310]

I'm with Lawrence with this.
A good old Advance E2 or similar will last for years and do exactly what you want.

[Bonky]

Thanks again; I know that's the general advice but the ones I've looked at seem dusty old rust boxes (both in and out) and with no guarantee of working correctly.

I'll keep looking though...

Richard.

[Mark Hennessy]

Whilst I've been hesitating to make specific recommendations, I've just picked up a Marconi TF2015. I've not had a chance to test it yet, but first impressions are pretty good.

Rather than the TF2015 though, I'd go for the similar TF2016 - this one is more suited to radio repairs.

These are relatively modern (early/mid '70s) and uses reliable solid-state components. Unlike a lot of Marconi gear, it's quite small and light. It can be AM and FM modulated, both internally and externally, so could be used with another oscillator to make a wobulator.

I've no idea what they fetch, but do some research and see if you think it's one to add to the shortlist.

[Bonky]

Thanks again Mark. I can't see any yet on Ebay but I'll keep looking!
R

[Refugee]

If you are really stuck for a sig gen I have got one that came as a donor for another.
I got both of them working nicely. They go up to 32Mhz but with harmonics into the domestic FM band. The extra one could be made available for sale.
The down side is that they are a bit heavy being made from new for the navy.
You would need to find an output connector as I only have one of those and also one of the cover clips is missing.
I have got another mains connector.

[Craig]

Thanks; just downloaded..and yes... it looks complicated!

R

Well, granted it can look a bit daunting. But just read the bits about voltage probes. The main message is that if you use a probe incorrectly you can chase your tail trying to diagnose what looks like a circuit fault whereas you are looking at an artifact of the probing method. There are a number of standard gotchas that the Tek probes document sets out with oscilloscope trace examples.

Craig

[pwdrive]

Thanks again; I know that's the general advice but the ones I've looked at seem dusty old rust boxes (both in and out) and with no guarantee of working correctly.

I'll keep looking though...

Richard.

Normally they shouldn't be much dust inside as most of these types of signal generators are usually well sealed to prevent RF leakage.

Lawrence.

[Bonky]

Well I'm the proud owner of a Hameg HM203-4 'scope. I paid £68 for it. I've no idea if that's good value (?) It came with a x10 Hameg probe and the original manual.

It's in very good cosmetic shape and displays a near-perfect sine wave (A small kink at the top of each wave). At first it seemed that it had two faults: The inbuilt sq wave generator for calibrating the probe didn't work (and still doesn't). The output is meant to be 0.2V but was only 0.1. I've adjusted the trimmer on the pcb to its max (but only 0.125V). Has anyone any advice?

Secondly the component tester didn't work. After having a good ferkle inside the gutlings I espied a loose transistor lead. Mending that seems to have restored that particular functionality.

Concerning the first problem I did adjust my sig gen to a 1kHz sq wave and adjusted the probe using that signal. Will that give me the same results as if the Hameg unit had been working properly?

Thanks everyone...

BW

Richard.