Function Generator Question

[pwdrive]

As title, any good for IF sweep alignment for say 5 Mhz on down?

Lawrence.

[Keithstv]

I have a Blackstar Jupiter 500 with a maximum frequency of about 500kHz. It has a sweep function but you need to feed a suitable signal into the sweep input. I've never used it for alignment but you have to careful as the sinewave output is not a pure output as it's a shaped triangle wave.

You may also find that the output level adjustment may be too coarse.

However if you've got a function generator which can be swept over the required range, try it.

Keith

[Neil F]

Yes, it can be done (I've done it a number of times), but I find it awkward. What you WANT to be able to do is set a centre frequency (e.g. 470 KHz) and then sweep from, say, 20 KHz below that to 20 KHz above it. Unfortunately, if your sweeper is anything like mine (an Exact model 500) you can't do that. Instead, you have to set the sweep start frequency on the main dial and the stop frequency on the knob marked...well, 'stop frequency', believe it or not. Problem is that there's no easy way to determine the centre frequency of the sweep (e.g. 470 KHz) without a separate signal generator to provide an appropriate 'pip' on the oscilloscope at that frequency. Nor is there a way of determining the stop frequency, though this isn't so much of a problem - you can do it well enough by eye on the oscilloscope.

All-in-all, it's a bit of a faff, and much harder than using a proper wobbulator. That said, it isn't by any means impossible, so yes, do have a go.

[pwdrive]

Thanks for the reply, as you say it sounds a bit of a faff, I don't have a function generator so my be I won't bother to buy one, I think I need to bide my time and wait for a Radivet or similar to turn up.

Lawrence.

Yes, it can be done (I've done it a number of times), but I find it awkward. What you WANT to be able to do is set a centre frequency (e.g. 470 KHz) and then sweep from, say, 20 KHz below that to 20 KHz above it. Unfortunately, if your sweeper is anything like mine (an Exact model 500) you can't do that. Instead, you have to set the sweep start frequency on the main dial and the stop frequency on the knob marked...well, 'stop frequency', believe it or not. Problem is that there's no easy way to determine the centre frequency of the sweep (e.g. 470 KHz) without a separate signal generator to provide an appropriate 'pip' on the oscilloscope at that frequency. Nor is there a way of determining the stop frequency, though this isn't so much of a problem - you can do it well enough by eye on the oscilloscope.

All-in-all, it's a bit of a faff, and much harder than using a proper wobbulator. That said, it isn't by any means impossible, so yes, do have a go.