The "Sussex" Homebrew Valve Tester. - Page 30 - UK Vintage Radio Repair and Restoration Discussion Forum

Mr_Klaatu · 28th Jul 2011, 1:32 pm

It's a fantastic project - all credit to you Mike.

Mine is still in the build stage, going well so far, finding time is the limiting factor.

I'll post some pics once its done.

What's next

mikeydee · 30th Aug 2011, 3:44 pm

Quote:

Originally Posted by swordholder

Over the next few days I will get together a write up and the PCB foil patterns and component layouts, together with setting up instructions and voltage readings from my prototype.

So pleased to find this thread on the VT1.

I would like to try and build one of these after realising that an AVO CT160/VCM 163 is probably going to be so hard to track down.

Could you send me the PCB layout diagrams, please?

swordholder · 30th Aug 2011, 10:30 pm

Hi,
There is a PCB layout on post27, if you contact G8UWM Mild Martin I think you will find he may have some PCBs left from a batch he had made.
Ed Dinning also produced a custom transformer.
I know it will be time consuming, but read through all the posts and you will find a wealth of information on the VT1.
Good luck with the build, mine is giving stirling service and has had no failures at all. You will also find several different interpretations of the layout, all looking really good.

Regards

Mike

M0XNA Neil · 1st Sep 2011, 7:16 pm

Mike,
My 'Sussex in a suitcase' is still working well and I am now making an octal adaptor to take wire ended valves.

Neil.

mikeydee · 15th Sep 2011, 4:04 pm

I have started gather parts for my Sussex (transformers, pcbs and meters all ordered). In terms of cases I like the portable approach so will have a look at the alluminium case approach taken by Neun Elf.

My outstanding question is on the rotary switches. Looking at Neun Elf's thumbwheel switches I think this design neatens up the wiring and will give better usability. There seemed to be some doubt about the low current and voltage rating on these type of devices - is there any update on their performance since the VT1 builds using these was some time ago also welcome any supplier suggestions.

MikeyDee

swordholder · 15th Sep 2011, 10:17 pm

Hello
Welcome to the builders!!
Although I haven't tried push button switches, I did obtain some from HK on E Bay. My concern with these is not so much with the contact, but with the width of the track connecting the contact with the rear connection strip. It does look as though it is less than 0.5mm wide. Avo contacts on their CTM163 for example are of a much beefier construction, a wide contact wiping on a silver plated rod.
The HK ones I bought, I rigged up a test using 2 in series with a power supply with an EL34 as the load, from memory there was over 0.5v drop across the switch. Not good enough in my opinion.
Let's wait and see what others say.

Regards

Mike

davegsm82 · 19th Sep 2011, 10:21 am

Hi Mike,

I've been watching this thread on the Sussex and I'm quite impressed.

Is there any chance you could condense the design, schematics, build instructions, parts list, operation etc into a few posts? Perhaps even the mods could sticky the thread so it stays clean?

I only ask as its quite difficult to keep track of changes/mods and the general build when its spread across 30 pages of text.

Dave.

RF Burn · 19th Sep 2011, 1:10 pm

Dave,

Les (Top Cap) has kindly produced an excellent document summarising the Sussex design, this can be found at post #502 which should appear on page 26

Adrian

Station X · 19th Sep 2011, 1:13 pm

The handbook is here:-

http://homepage.ntlworld.com/lez/Sus...%20version.doc

loftfullofradio · 10th Oct 2011, 7:41 pm

Hi. I'm just starting my own variant of the Sussex. I have breadboarded the oscillator and found it very temperature sensitive. The o/p rises with temp, does anyone else find this?

swordholder · 12th Oct 2011, 7:44 am

Hi,
Welcome to the "Sussex Group", I haven't noticed any great variation with temperature on mine, by how much is it varying?
As you can see there is no temperature compensation. Are you using good quality capacitors, not ceramic, as this may cause the problem.

Regards

Mike

FRANK.C · 12th Oct 2011, 1:04 pm

Hi loftfullofradio
I have experienced the same phenomenon. See post 460.

Frank

RF Burn · 12th Oct 2011, 3:19 pm

Loftfull,

I am also designing my version of the Sussex VT, my solution to this problem is to use a small cheap 8 pin PIC12F1840 device to generate a rock stable 50Hz sine wave from it's D/A converter, with the supply reduced to 3 - 5 Volts. Works a treat, I will post details when I can find a spare moment...!

Adrian

loftfullofradio · 12th Oct 2011, 7:03 pm

Hi gents.

I find if you set the pot so the oscillator just runs and starts OK, the O/P rise with temp is worse than if it's turned right up. I've breadboarded an osc with a lamp filament in the feedback to stabilise it, however the output has an LF breathing effect. Perhaps due the the thermal time constant of the lamp (about 1Hz). The pic idea sounds good. It should be as stable as the DC supply of the D to A. I will look at post 460.

Thanks for the thoughts so far.

John

loftfullofradio · 13th Oct 2011, 7:38 pm

Sorry. Missed swordholders question. Set to 100mv rms o/p at room temp, rises to over 130mv after 5 mins under my desk lamp, A crude test I know but my shack is in the loft so varies from frost to sauna, winter to summer. The lamp stabilised one rises to about 106mv but needs the lamp fillament shaded or the light warms it through the glass worsenning the drift. As you can see I'm over analysing already. I am awaiting a transformer from Ed so I have plenty of time to worry this problem to death. But if sword holders osc is ok and a few are not, it looks like it may be down to components.
Best wishes to all John

PyrusBoy · 14th Oct 2011, 9:43 am

Good Morning all,
I'm not posting very often, but I wonder if anyone can tell me if and where I can obtain transformer and PCB. Interesting project for the winter months as I have 20 or so vintage radios and 1 VT1 Tele, and more to refurb..
Thanks

FRANK.C · 14th Oct 2011, 12:17 pm

Quote:

Originally Posted by loftfullofradio

it looks like it may be down to components.

Hi John
I have similar temperature variations in my shack.
By heating and cooling each component individually in my build of the original oscillator I found the main culprits to be the transistors TR6 and TR7, but in particular TR7. I tried different transistors in those positions, some did improve the situation, but none were good enough for the temperature variation in my shack.

Frank

swordholder · 14th Oct 2011, 3:41 pm

Quote:

Originally Posted by PyrusBoy

I wonder if anyone can tell me if and where I can obtain transformer and PCB.

Hi,
Transformer available from ED and PCB from Martin. See previous posts for prices and availability

Mike

Ed_Dinning · 14th Oct 2011, 7:15 pm

H Gents, transformers are still available if needed.
Pyrus Boy, you have a PM.

Ed

a_strong · 5th Nov 2011, 10:26 am

Anyone considering using the EBay Chinese thumbwheel switches (as I was!) may be interested in the response to my question: "Dear Sirs - what are the AC and DC voltage and current ratings for this product?".

Quote:

"Thanks for your interest in our item 350502322177. Generally it can be used within DC 24V , and it is 0.5A. Feel free to contact us if you need any assistance. Have a nice day."

End quote.

Alan G3WXI

28th Jul 2011, 1:32 pm	#581
Mr_Klaatu Retired Dormant Member Join Date: Jun 2009 Location: East Coast, Singapore Posts: 16	Re: The "Sussex" Homebrew Valve Tester. It's a fantastic project - all credit to you Mike. Mine is still in the build stage, going well so far, finding time is the limiting factor. I'll post some pics once its done. What's next

30th Aug 2011, 10:30 pm	#583
swordholder Rest in Peace Join Date: Aug 2009 Location: East Preston, Sussex Posts: 162	Re: The "Sussex" Homebrew Valve Tester. Hi, There is a PCB layout on post27, if you contact G8UWM Mild Martin I think you will find he may have some PCBs left from a batch he had made. Ed Dinning also produced a custom transformer. I know it will be time consuming, but read through all the posts and you will find a wealth of information on the VT1. Good luck with the build, mine is giving stirling service and has had no failures at all. You will also find several different interpretations of the layout, all looking really good. Regards Mike

1st Sep 2011, 7:16 pm	#584
M0XNA Neil Tetrode Join Date: Apr 2009 Location: Towcester, Northamptonshire, UK. Posts: 92	Re: The "Sussex" Homebrew Valve Tester. Mike, My 'Sussex in a suitcase' is still working well and I am now making an octal adaptor to take wire ended valves. Neil. __________________ An engineer makes for a penny what a scientist makes for a pound!

15th Sep 2011, 4:04 pm	#585
mikeydee Tetrode Join Date: Aug 2011 Location: Bristol, UK. Posts: 67	Re: The "Sussex" Homebrew Valve Tester. I have started gather parts for my Sussex (transformers, pcbs and meters all ordered). In terms of cases I like the portable approach so will have a look at the alluminium case approach taken by Neun Elf. My outstanding question is on the rotary switches. Looking at Neun Elf's thumbwheel switches I think this design neatens up the wiring and will give better usability. There seemed to be some doubt about the low current and voltage rating on these type of devices - is there any update on their performance since the VT1 builds using these was some time ago also welcome any supplier suggestions. MikeyDee

15th Sep 2011, 10:17 pm	#586
swordholder Rest in Peace Join Date: Aug 2009 Location: East Preston, Sussex Posts: 162	Re: The "Sussex" Homebrew Valve Tester. Hello Welcome to the builders!! Although I haven't tried push button switches, I did obtain some from HK on E Bay. My concern with these is not so much with the contact, but with the width of the track connecting the contact with the rear connection strip. It does look as though it is less than 0.5mm wide. Avo contacts on their CTM163 for example are of a much beefier construction, a wide contact wiping on a silver plated rod. The HK ones I bought, I rigged up a test using 2 in series with a power supply with an EL34 as the load, from memory there was over 0.5v drop across the switch. Not good enough in my opinion. Let's wait and see what others say. Regards Mike

19th Sep 2011, 10:21 am	#587
davegsm82 Heptode Join Date: Jan 2004 Location: Blyth, Northumberland, UK. Posts: 858	Re: The "Sussex" Homebrew Valve Tester. Hi Mike, I've been watching this thread on the Sussex and I'm quite impressed. Is there any chance you could condense the design, schematics, build instructions, parts list, operation etc into a few posts? Perhaps even the mods could sticky the thread so it stays clean? I only ask as its quite difficult to keep track of changes/mods and the general build when its spread across 30 pages of text. Dave. Last edited by Mike Phelan; 11th Oct 2011 at 9:55 am. Reason: Corrected typos.

19th Sep 2011, 1:10 pm	#588
RF Burn Hexode Join Date: Apr 2008 Location: Ramsgate, Kent, UK. Posts: 252	Re: The "Sussex" Homebrew Valve Tester. Dave, Les (Top Cap) has kindly produced an excellent document summarising the Sussex design, this can be found at post #502 which should appear on page 26 Adrian

19th Sep 2011, 1:13 pm	#589
Station X Moderator Join Date: Jan 2003 Location: Ipswich, Suffolk, IP4, UK. Posts: 21,287	Re: The "Sussex" Homebrew Valve Tester. The handbook is here:- http://homepage.ntlworld.com/lez/Sus...%20version.doc __________________ Graham. Forum Moderator Reach for your meter before you reach for your soldering iron.

10th Oct 2011, 7:41 pm	#590
loftfullofradio Retired Dormant Member Join Date: Feb 2009 Location: Manchester UK Posts: 3	Re: The "Sussex" Homebrew Valve Tester. Hi. I'm just starting my own variant of the Sussex. I have breadboarded the oscillator and found it very temperature sensitive. The o/p rises with temp, does anyone else find this? Last edited by Mike Phelan; 11th Oct 2011 at 9:57 am. Reason: Corrected typos.

12th Oct 2011, 7:44 am	#591
swordholder Rest in Peace Join Date: Aug 2009 Location: East Preston, Sussex Posts: 162	Re: The "Sussex" Homebrew Valve Tester. Hi, Welcome to the "Sussex Group", I haven't noticed any great variation with temperature on mine, by how much is it varying? As you can see there is no temperature compensation. Are you using good quality capacitors, not ceramic, as this may cause the problem. Regards Mike

12th Oct 2011, 1:04 pm	#592
FRANK.C Heptode Join Date: Feb 2006 Location: Roscommon, Ireland Posts: 732	Re: The "Sussex" Homebrew Valve Tester. Hi loftfullofradio I have experienced the same phenomenon. See post 460. Frank

12th Oct 2011, 3:19 pm	#593
RF Burn Hexode Join Date: Apr 2008 Location: Ramsgate, Kent, UK. Posts: 252	Re: The "Sussex" Homebrew Valve Tester. Loftfull, I am also designing my version of the Sussex VT, my solution to this problem is to use a small cheap 8 pin PIC12F1840 device to generate a rock stable 50Hz sine wave from it's D/A converter, with the supply reduced to 3 - 5 Volts. Works a treat, I will post details when I can find a spare moment...! Adrian Last edited by RF Burn; 12th Oct 2011 at 3:22 pm. Reason: Typo

12th Oct 2011, 7:03 pm	#594
loftfullofradio Retired Dormant Member Join Date: Feb 2009 Location: Manchester UK Posts: 3	Re: The "Sussex" Homebrew Valve Tester. Hi gents. I find if you set the pot so the oscillator just runs and starts OK, the O/P rise with temp is worse than if it's turned right up. I've breadboarded an osc with a lamp filament in the feedback to stabilise it, however the output has an LF breathing effect. Perhaps due the the thermal time constant of the lamp (about 1Hz). The pic idea sounds good. It should be as stable as the DC supply of the D to A. I will look at post 460. Thanks for the thoughts so far. John

13th Oct 2011, 7:38 pm	#595
loftfullofradio Retired Dormant Member Join Date: Feb 2009 Location: Manchester UK Posts: 3	Re: The "Sussex" Homebrew Valve Tester. Sorry. Missed swordholders question. Set to 100mv rms o/p at room temp, rises to over 130mv after 5 mins under my desk lamp, A crude test I know but my shack is in the loft so varies from frost to sauna, winter to summer. The lamp stabilised one rises to about 106mv but needs the lamp fillament shaded or the light warms it through the glass worsenning the drift. As you can see I'm over analysing already. I am awaiting a transformer from Ed so I have plenty of time to worry this problem to death. But if sword holders osc is ok and a few are not, it looks like it may be down to components. Best wishes to all John

14th Oct 2011, 9:43 am	#596
PyrusBoy Triode Join Date: Jun 2011 Location: Gillingham Posts: 17	Re: The "Sussex" Homebrew Valve Tester. Good Morning all, I'm not posting very often, but I wonder if anyone can tell me if and where I can obtain transformer and PCB. Interesting project for the winter months as I have 20 or so vintage radios and 1 VT1 Tele, and more to refurb.. Thanks

14th Oct 2011, 7:15 pm	#599
Ed_Dinning Dekatron Join Date: Jan 2004 Location: Newcastle upon Tyne, Tyne & Wear, UK. Posts: 8,194	Re: The "Sussex" Homebrew Valve Tester. H Gents, transformers are still available if needed. Pyrus Boy, you have a PM. Ed

5th Nov 2011, 10:26 am	#600
a_strong Pentode Join Date: Feb 2007 Location: South Yorkshire, UK. Posts: 134	Re: The "Sussex" Homebrew Valve Tester. Anyone considering using the EBay Chinese thumbwheel switches (as I was!) may be interested in the response to my question: "Dear Sirs - what are the AC and DC voltage and current ratings for this product?". Quote: "Thanks for your interest in our item 350502322177. Generally it can be used within DC 24V , and it is 0.5A. Feel free to contact us if you need any assistance. Have a nice day." End quote. Alan G3WXI