VFO, and noise source. I need a bit of advice please. - UK Vintage Radio Repair and Restoration Discussion Forum

Paul Collins · 9th Jul 2013, 8:49 pm

I need to build a wide range VFO, and also a noise source quite rich in noise content, can any of you please point me in the right direction.
Paul de M0BSW

lesmw0sec · 11th Jul 2013, 11:40 am

If you are happy going the digital route, have you considered using the AD9850 which I think is still available on Amazon for a few quid? Ideal for an audio-HF VFO which can be tuned in 1 c/s increments, accuracy to crystal clock. Needs to be controlled with a processor or PIC though.

Les.

P.S. Just thought - you could probably do the noise as well, with a pseudo-random sequence, but a diode might be simpler!

G8HQP Dave · 11th Jul 2013, 12:57 pm

What do you mean by 'wide range'? Like a multi-range RF sig gen, or like a MW tuner, or merely a bit wider than an amateur band?

What do you mean by 'rich in noise content'? All noise sources do that. Frequency range? What is it for? Receiver alignment, or receiver measurement? Loudspeaker measurement? Audio synthesiser?

We need to know about the application.

Paul Collins · 11th Jul 2013, 4:20 pm

Quote:

Originally Posted by G8HQP Dave

What do you mean by 'wide range'? Like a multi-range RF sig gen, or like a MW tuner, or merely a bit wider than an amateur band?

What do you mean by 'rich in noise content'? All noise sources do that. Frequency range? What is it for? Receiver alignment, or receiver measurement? Loudspeaker measurement? Audio synthesiser?

We need to know about the application.

Yes Dave spot on ,receiver IF alignment, is exactly what I want to do. not really sure what I need, so any help would be excellent stuffed with it at the moment.
Paul de M0BSW .

G8HQP Dave · 11th Jul 2013, 6:39 pm

You need to decide what you need before buying/making it. What sort of receiver? IF frequency? AM? FM? SSB? We are smart, but we don't read minds.

If you are starting from scratch then a cheapish RF sig gen may be the answer, or a good second-hand one (e.g. Advance).

Paul Collins · 12th Jul 2013, 8:31 am

Quote:

Originally Posted by G8HQP Dave

You need to decide what you need before buying/making it. What sort of receiver? IF frequency? AM? FM? SSB? We are smart, but we don't read minds.

If you are starting from scratch then a cheapish RF sig gen may be the answer, or a good second-hand one (e.g. Advance).

455mhz, AM,MW,LW

G8HQP Dave · 12th Jul 2013, 11:22 am

Quote:

455mhz, AM,MW,LW

I assume you mean 455kHz. 455mHz is slower than the rotation speed of a 33rpm LP.

You need a cheap RF sig gen. Or make one.

Paul Collins · 12th Jul 2013, 11:42 am

Yes sorry hit wrong key yes I have a signal generator ,think I'll make though need the practise,plus the pure fun of it as well, thank you for replying Dave.

9th Jul 2013, 8:49 pm	#1
Paul Collins Retired Dormant Member Join Date: Apr 2013 Location: Peterborough, Cambs. UK. Posts: 17	VFO, and noise source. I need a bit of advice please. I need to build a wide range VFO, and also a noise source quite rich in noise content, can any of you please point me in the right direction. Paul de M0BSW

11th Jul 2013, 11:40 am	#2
lesmw0sec Octode Join Date: Jul 2009 Location: Carmel, Llannerchymedd, Anglesey, UK. Posts: 1,507	Re: VFO, and noise source. I need a bit of advice please. If you are happy going the digital route, have you considered using the AD9850 which I think is still available on Amazon for a few quid? Ideal for an audio-HF VFO which can be tuned in 1 c/s increments, accuracy to crystal clock. Needs to be controlled with a processor or PIC though. Les. P.S. Just thought - you could probably do the noise as well, with a pseudo-random sequence, but a diode might be simpler! Last edited by lesmw0sec; 11th Jul 2013 at 11:42 am. Reason: Addition

11th Jul 2013, 12:57 pm	#3
G8HQP Dave Rest in Peace Join Date: Sep 2008 Location: Solihull, West Midlands, UK. Posts: 4,872	Re: VFO, and noise source. I need a bit of advice please. What do you mean by 'wide range'? Like a multi-range RF sig gen, or like a MW tuner, or merely a bit wider than an amateur band? What do you mean by 'rich in noise content'? All noise sources do that. Frequency range? What is it for? Receiver alignment, or receiver measurement? Loudspeaker measurement? Audio synthesiser? We need to know about the application.

11th Jul 2013, 6:39 pm	#5
G8HQP Dave Rest in Peace Join Date: Sep 2008 Location: Solihull, West Midlands, UK. Posts: 4,872	Re: VFO, and noise source. I need a bit of advice please. You need to decide what you need before buying/making it. What sort of receiver? IF frequency? AM? FM? SSB? We are smart, but we don't read minds. If you are starting from scratch then a cheapish RF sig gen may be the answer, or a good second-hand one (e.g. Advance).

12th Jul 2013, 11:42 am	#8
Paul Collins Retired Dormant Member Join Date: Apr 2013 Location: Peterborough, Cambs. UK. Posts: 17	Re: VFO, and noise source. I need a bit of advice please. Yes sorry hit wrong key yes I have a signal generator ,think I'll make though need the practise,plus the pure fun of it as well, thank you for replying Dave.