The Radio Bygones wobbulator by Raymond Haigh. - UK Vintage Radio Repair and Restoration Discussion Forum

Mike Phelan · 31st Dec 2013, 5:17 pm

Though it’s quite possible to carry out a complete alignment of an AM/FM radio using just a signal generator and ‘scope, a wobbulator is a useful bit of gear.

As it was quite a while since I had a go at making any test equipment and I’ve a nice fifties German table radio that I suspect has had the attention of the twiddle fairy that would be a good enough reason to make a wobbulator.

There have been a few over the years, both valve and transistor, but I settled on the Raymond Haigh design from Radio Bygones.

I had most of the bits except the Toko coils and needed to make a PCB..
Jabdog supplied all the coils, fortunately. A pleasant bunch to deal with.

When chatting to David (G4EBT) he mentioned that he had made one of these and had a few spare PCB’s, plus the fact that member Colin (Armstrong) had made a modification to give a better variable X-sweep using a 555 chip. David also had a spare PCB for this part!

So, off we went to the playroom. I used a mains power supply instead of the original battery and found a few hardwood strips for the case.

The front panel is grained aluminium alloy with waterslide transfers for the graduations.

I comb-jointed the wood and built the chassis to carry the printed boards; tried a few different ways as space is a bit tight due to the width of the hardwood I had.
I’m still not 100% happy with the panel layout and wiring, but time to try it.
After a few of the usual bits of mistakery we had a couple of running oscillators so that’s it for now, as Christmassy things needed to be done; we’ll give it a proper test in 2014 and point it at my Nordmende radio,

Mike Brett · 31st Dec 2013, 6:53 pm

Looks a very purposeful well built unit, I particularly like the innovative chassis design , very well thought out piece of test kit.
Mike

David G4EBT · 31st Dec 2013, 7:49 pm

Just a little note of caution if anyone has built or intends to build this nice little project: On the PCB overlay in the article, the range 3 & 4 coils need to be swapped over, as a glance at the circuit in comparison with the layout will show. I didn't discover that until I checked the coverage of the ranges on my frequency counter.

I too would like to record my thanks to Colin Armstrong for his valued assistance, including the the sweep generator circuit and the revised from panel design to accommodate the addition of the sweep generator control.

The main challenge for anyone tempted to build the project is sourcing the long since obsolete Toko coils. (The project was published in RB is 2003). I don't know if Peter at Jabdog still has any.

julie_m · 1st Jan 2014, 5:22 am

Thinking out loud, there must be plenty of nothing-special radiocassettes from the 1980s and 1990s with long-since-perished rubber in the cassette mechanisms, that are now just being kept for the radio for a bit of background sound; and they would all have been to fairly similar designs, dictated by the ICs used. Would such a receiver yield any useful wound parts?

Mike Phelan · 1st Jan 2014, 10:39 am

Thanks, David, for the nudge about the error in the circuit. Fortunately I did spot it when I looked at it originally.

Until I discovered Jabdog's Toko coils I did consider rewinding scrap IF transformers with the same sized formers from junked radios, as the inductance doesn't need to be precise with having a counter instead of a calibrated scale.

Colin Ames · 2nd Jan 2014, 8:49 pm

Mike,
That's a nice piece of kit you've put together. I'd like to build one of these, but before I order the back issue of Radio Bygones on CD, I would like to verify that the coils are still available from Jabdog. If it's not too much trouble, could you please post the part numbers of the coils so that I can contact Jabdog?

Many thanks in advance of your help.

Regards,
Colin

Mike Phelan · 3rd Jan 2014, 6:15 pm

Colin,

The original spec Toko coils, now unavailable, were:
L1 - RW06A7752EK (green core)
L2 - 154FN8A6438EK (violet core)
L3 - 154FN8A6439EK (yellow core)
L4 - KXNK3767EK (pink core)

Jabdog will tell you what the equivalents are if they still have them in stock.

HTH

Radio Wrangler · 3rd Jan 2014, 7:05 pm

Mike,

Jabdog's stand is usually at the G-QRP doo at Rishworth every October, and he sometimes has trays of toko formers and cans. Only about 30 mins away from you, but only once a year.

Might be worth developing toroid equivalents, but the lack of a twiddler is the usual problem.

David

Colin Ames · 3rd Jan 2014, 10:26 pm

Mike,

Thanks for the information.

Regards,
Colin

Mark James · 8th Feb 2014, 7:16 pm

Another RH wobbulator! I am indebted to David for the PCB's and very useful advice and to Colin for the sweep generator circuit. I have managed to fit it into an old Avo box leaving a gap at the front for the leads and RF probe - the latter was described in the following Radio Bygones issue from the wobbulator. I housed the batteries in a double battery holder with pull out drawers which just fits within a gap in the 'works' and avoids having loose batteries in the storage compartment - visible with the drawers pulled out in one of the pictures. (A Bulgin component available from CPC - usual disclaimer etc.) I have attached some pictures and as you can see from the trace it works!

Mark

Colin Ames · 8th Feb 2014, 7:57 pm

Nice job Mark!

Colin

David G4EBT · 9th Feb 2014, 11:38 am

Well done in completing the 'wobby' Mark - the AVO box looks as though it was made for the job!

The RF Probe looks good too. (A bit of a fiddly task to squeeze everything into the little Maplin probe box, eh!)

31st Dec 2013, 5:17 pm	#1
Mike Phelan Dekatron Join Date: Nov 2003 Location: Near Leeds, West Yorkshire, UK Posts: 4,609	The Radio Bygones wobbulator by Raymond Haigh. Though it’s quite possible to carry out a complete alignment of an AM/FM radio using just a signal generator and ‘scope, a wobbulator is a useful bit of gear. As it was quite a while since I had a go at making any test equipment and I’ve a nice fifties German table radio that I suspect has had the attention of the twiddle fairy that would be a good enough reason to make a wobbulator. There have been a few over the years, both valve and transistor, but I settled on the Raymond Haigh design from Radio Bygones. I had most of the bits except the Toko coils and needed to make a PCB.. Jabdog supplied all the coils, fortunately. A pleasant bunch to deal with. When chatting to David (G4EBT) he mentioned that he had made one of these and had a few spare PCB’s, plus the fact that member Colin (Armstrong) had made a modification to give a better variable X-sweep using a 555 chip. David also had a spare PCB for this part! So, off we went to the playroom. I used a mains power supply instead of the original battery and found a few hardwood strips for the case. The front panel is grained aluminium alloy with waterslide transfers for the graduations. I comb-jointed the wood and built the chassis to carry the printed boards; tried a few different ways as space is a bit tight due to the width of the hardwood I had. I’m still not 100% happy with the panel layout and wiring, but time to try it. After a few of the usual bits of mistakery we had a couple of running oscillators so that’s it for now, as Christmassy things needed to be done; we’ll give it a proper test in 2014 and point it at my Nordmende radio, Attached Thumbnails __________________ Mike.

31st Dec 2013, 6:53 pm	#2
Mike Brett Retired Dormant Member Join Date: Dec 2005 Location: Wisbech, Cambridgeshire, UK. Posts: 452	Re: The Radio Bygones wobbulator by Raymond Haigh. Looks a very purposeful well built unit, I particularly like the innovative chassis design , very well thought out piece of test kit. Mike

31st Dec 2013, 7:49 pm	#3
David G4EBT Dekatron Join Date: Feb 2003 Location: Cottingham, East Yorkshire, UK. Posts: 5,760	Re: The Radio Bygones wobbulator by Raymond Haigh. Just a little note of caution if anyone has built or intends to build this nice little project: On the PCB overlay in the article, the range 3 & 4 coils need to be swapped over, as a glance at the circuit in comparison with the layout will show. I didn't discover that until I checked the coverage of the ranges on my frequency counter. I too would like to record my thanks to Colin Armstrong for his valued assistance, including the the sweep generator circuit and the revised from panel design to accommodate the addition of the sweep generator control. The main challenge for anyone tempted to build the project is sourcing the long since obsolete Toko coils. (The project was published in RB is 2003). I don't know if Peter at Jabdog still has any. Attached Thumbnails __________________ David. BVWS Member. G-QRP Club member 1339.

1st Jan 2014, 5:22 am	#4
julie_m Dekatron Join Date: May 2008 Location: Derby, UK. Posts: 7,735	Re: The Radio Bygones wobbulator by Raymond Haigh. Thinking out loud, there must be plenty of nothing-special radiocassettes from the 1980s and 1990s with long-since-perished rubber in the cassette mechanisms, that are now just being kept for the radio for a bit of background sound; and they would all have been to fairly similar designs, dictated by the ICs used. Would such a receiver yield any useful wound parts? __________________ If I have seen further than others, it is because I was standing on a pile of failed experiments.

1st Jan 2014, 10:39 am	#5
Mike Phelan Dekatron Join Date: Nov 2003 Location: Near Leeds, West Yorkshire, UK Posts: 4,609	Re: The Radio Bygones wobbulator by Raymond Haigh. Thanks, David, for the nudge about the error in the circuit. Fortunately I did spot it when I looked at it originally. Until I discovered Jabdog's Toko coils I did consider rewinding scrap IF transformers with the same sized formers from junked radios, as the inductance doesn't need to be precise with having a counter instead of a calibrated scale. __________________ Mike.

2nd Jan 2014, 8:49 pm	#6
Colin Ames Tetrode Join Date: Mar 2010 Location: Monroe, Georgia, USA. (from Coventry, UK). Posts: 77	Re: The Radio Bygones wobbulator by Raymond Haigh. Mike, That's a nice piece of kit you've put together. I'd like to build one of these, but before I order the back issue of Radio Bygones on CD, I would like to verify that the coils are still available from Jabdog. If it's not too much trouble, could you please post the part numbers of the coils so that I can contact Jabdog? Many thanks in advance of your help. Regards, Colin

3rd Jan 2014, 6:15 pm	#7
Mike Phelan Dekatron Join Date: Nov 2003 Location: Near Leeds, West Yorkshire, UK Posts: 4,609	Re: The Radio Bygones wobbulator by Raymond Haigh. Colin, The original spec Toko coils, now unavailable, were: L1 - RW06A7752EK (green core) L2 - 154FN8A6438EK (violet core) L3 - 154FN8A6439EK (yellow core) L4 - KXNK3767EK (pink core) Jabdog will tell you what the equivalents are if they still have them in stock. HTH __________________ Mike. Last edited by Mike Phelan; 4th Jan 2014 at 9:20 am. Reason: Typos corrected.

3rd Jan 2014, 7:05 pm	#8
Radio Wrangler Moderator Join Date: Mar 2012 Location: Fife, Scotland, UK. Posts: 22,858	Re: The Radio Bygones wobbulator by Raymond Haigh. Mike, Jabdog's stand is usually at the G-QRP doo at Rishworth every October, and he sometimes has trays of toko formers and cans. Only about 30 mins away from you, but only once a year. Might be worth developing toroid equivalents, but the lack of a twiddler is the usual problem. David __________________ Can't afford the volcanic island yet, but the plans for my monorail and the goons' uniforms are done

3rd Jan 2014, 10:26 pm	#9
Colin Ames Tetrode Join Date: Mar 2010 Location: Monroe, Georgia, USA. (from Coventry, UK). Posts: 77	Re: The Radio Bygones wobbulator by Raymond Haigh. Mike, Thanks for the information. Regards, Colin

8th Feb 2014, 7:16 pm	#10
Mark James Hexode Join Date: Apr 2012 Location: Chorley, Lancashire, UK. Posts: 260	Re: The Radio Bygones wobbulator by Raymond Haigh. Another RH wobbulator! I am indebted to David for the PCB's and very useful advice and to Colin for the sweep generator circuit. I have managed to fit it into an old Avo box leaving a gap at the front for the leads and RF probe - the latter was described in the following Radio Bygones issue from the wobbulator. I housed the batteries in a double battery holder with pull out drawers which just fits within a gap in the 'works' and avoids having loose batteries in the storage compartment - visible with the drawers pulled out in one of the pictures. (A Bulgin component available from CPC - usual disclaimer etc.) I have attached some pictures and as you can see from the trace it works! Mark Attached Thumbnails

8th Feb 2014, 7:57 pm	#11
Colin Ames Tetrode Join Date: Mar 2010 Location: Monroe, Georgia, USA. (from Coventry, UK). Posts: 77	Re: The Radio Bygones wobbulator by Raymond Haigh. Nice job Mark! Colin

9th Feb 2014, 11:38 am	#12
David G4EBT Dekatron Join Date: Feb 2003 Location: Cottingham, East Yorkshire, UK. Posts: 5,760	Re: The Radio Bygones wobbulator by Raymond Haigh. Well done in completing the 'wobby' Mark - the AVO box looks as though it was made for the job! The RF Probe looks good too. (A bit of a fiddly task to squeeze everything into the little Maplin probe box, eh!) __________________ David. BVWS Member. G-QRP Club member 1339.