All wave signal generator 1943 - VR135 valves - UK Vintage Radio Repair and Restoration Discussion Forum

oldgeezer · 3rd Jan 2015, 2:59 pm

Well, my Derwent set is causing some headaches in the RF department so I went to the attic pile and thought I'd find a RF sig generator.

I did, but its not producing RF (but does the transformer rattle and hum!).

It should be pretty simple and has HT 50v and heaters light. Does anyone have a circuit or info?

The power output meter is dated 1943 and is not connected as it is O/C. I assume A M on the variable cap means air ministry?

cheers
Keith

Alan Stepney · 3rd Jan 2015, 3:12 pm

These were made and supplied as a kit (or assembled) by one of the well known London dealers, but I dont recall who it was right now.
(Radio & TV components perhaps?)

They were basic and made using ex-government parts.
Yes, AM does mean Air Ministry.

AC/HL · 3rd Jan 2015, 6:11 pm

They are very simple. The HT seems low. That rectifier could be the problem, as could any paper capacitors, whatever their make. Is the smoothing capacitor getting hot?

HamishBoxer · 3rd Jan 2015, 9:39 pm

I think I would be a bit suspious of the main smoothing cap with that HT.

paulsherwin · 3rd Jan 2015, 9:48 pm

You have a bad selenium rectifier. Bridge it with a 1N4007 and see what happens.

HT is typically about 100V in these things though it does depend on whatever surplus transformer was available.

oldgeezer · 3rd Jan 2015, 10:37 pm

Many thanks - I bridged the rectifier with a handy silicon one.
97v and now working well.

Now to sort out the Derwent - (I knew it was going to be trouble!)
cheers
Keith

space charge · 15th Jan 2015, 11:45 pm

is it the de luxe version of the homelab signal generator.pierce ei7ka

3rd Jan 2015, 2:59 pm	#1
oldgeezer Pentode Join Date: Oct 2014 Location: St Albans, Hertfordshire, UK. Posts: 135	All wave signal generator 1943 - VR135 valves Well, my Derwent set is causing some headaches in the RF department so I went to the attic pile and thought I'd find a RF sig generator. I did, but its not producing RF (but does the transformer rattle and hum!). It should be pretty simple and has HT 50v and heaters light. Does anyone have a circuit or info? The power output meter is dated 1943 and is not connected as it is O/C. I assume A M on the variable cap means air ministry? cheers Keith Attached Thumbnails

3rd Jan 2015, 3:12 pm	#2
Alan Stepney Rest in Peace Join Date: Feb 2008 Location: Dorset, UK. Posts: 947	Re: All wave signal generator 1943 - VR135 valves These were made and supplied as a kit (or assembled) by one of the well known London dealers, but I dont recall who it was right now. (Radio & TV components perhaps?) They were basic and made using ex-government parts. Yes, AM does mean Air Ministry.

3rd Jan 2015, 6:11 pm	#3
AC/HL Dekatron Join Date: Nov 2003 Location: Heckmondwike, West Yorkshire, UK. Posts: 9,642	Re: All wave signal generator 1943 - VR135 valves They are very simple. The HT seems low. That rectifier could be the problem, as could any paper capacitors, whatever their make. Is the smoothing capacitor getting hot?

3rd Jan 2015, 9:39 pm	#4
HamishBoxer Dekatron Join Date: Aug 2007 Location: W.Butterwick, near Doncaster UK. Posts: 8,935	Re: All wave signal generator 1943 - VR135 valves I think I would be a bit suspious of the main smoothing cap with that HT. __________________ G8JET BVWS Archivist and Member V.M.A.R.S

3rd Jan 2015, 9:48 pm	#5
paulsherwin Moderator Join Date: Jun 2003 Location: Oxford, UK Posts: 27,970	Re: All wave signal generator 1943 - VR135 valves You have a bad selenium rectifier. Bridge it with a 1N4007 and see what happens. HT is typically about 100V in these things though it does depend on whatever surplus transformer was available.

3rd Jan 2015, 10:37 pm	#6
oldgeezer Pentode Join Date: Oct 2014 Location: St Albans, Hertfordshire, UK. Posts: 135	Re: All wave signal generator 1943 - VR135 valves Many thanks - I bridged the rectifier with a handy silicon one. 97v and now working well. Now to sort out the Derwent - (I knew it was going to be trouble!) cheers Keith

15th Jan 2015, 11:45 pm	#7
space charge Tetrode Join Date: May 2013 Location: Enniscorthy, County Wexford, Ireland. Posts: 74	Re: All wave signal generator 1943 - VR135 valves is it the de luxe version of the homelab signal generator.pierce ei7ka