The "Sussex" Homebrew Valve Tester.

[mikeydee]

My Sussex build is complete here are the final pictures. More details on my build diary thread.

For me this was my biggest homebrew project to date and I have learnt such a lot from the forum and Mike Rowe's original fantastic design.

My personal lessons were:

• Print the panel before cutting. I did it the other way round which made it very difficult to align things.
• The case that I used was ok in the end. Initially I regretted buying it as it's a bit flimsy but now that the base is lined with Aluminium actually it's pretty solid.
• Colour code all the wiring; without it debugging is tough.
• The D connectors worked very well
• Don't use maplin choc a bloc the screws are made of very soft metal.
• Stop faffing about and get on with it . . .

I will try to help others with their build if I can.

[Top Cap]

Nice one Mike, looks good. I took on-board some of your comments and added them to the guide. Actually it was never meant as a guide, more like a "This is how I did it" but very flattered that you used it for your build. I am like it at work when I get asked to make something, I produce a complete drawing package and commissioning instructions etc. before I actually start making it!
Once again. thanks for the constructive comments, Les

[Anthony Thomas]

Oh my! what a wonderfull construction by any way you look at it. The last comment about cutting out the faffing is sound advice

Tony

[Anthony Thomas]

Originally Posted by ColinTheAmpMan1

As far as I can see, there is no declaration of the value of the enclosed items, so you might get lucky, too.

Norwegian customs are notorious for stiffing us on anything over NKr 200,- including postage, peanuts these days I know but I like the challenge in finding out how to make do with the spares box. Usable DVM are available locally for about NKr 100,- each so they might just be my choice.

Again Thanks
Tony

[Mike Brett]

Hi all
I am in the process of populating my board and am confused by the orientation of the 1N4007 diode D14 that is connected across relay RL1. Now the schematic clearly shows the cathode connected to A1 on the relay and the terminal AH. BUT if you look at the actual pcb board the tracking from the AH terminal goes to the A2 pin not the A1 pin. Are the A1 and A2 markings on the board layout reversed.
Mike

[G8UWM-MildMartin]

Hi Mike,
The circuit is correct:
The cathode goes to the terminal/ pin (AH) and the anode to the negative LV rail.
(Which means the component layout and the couple of boards I've built are wrong.)
Again, well spotted!
Regards,
Martin.

[mikeydee]

Well Spotted to Mike Brett for noticing that the mod I have suggested around RL1 is incorrect because I have cut the track before C2 effectively shifting it to after the fuse, see diagram.

Below is a photo with a clarification of where I think that the the cut should be which TopCap has corrected in the guide so we are up to date with the documentation.

Mike

[Mike Brett]

Help please.
I have almost finished populating my Sussex boards apart from two resistors left over.
One is R6 which is a 120R, the other is R40 a 47R. On the schematic R6 is across pins AJ20 and AK21 on the top right of the board. Although there are two holes in the actual board this resistor is not shown on the board layout. I assume this is an omission mistake. I have looked at the schematic but have failed to locate the R40 resistor anywhere.Looking at other members completed boards there appears to be two resistors across pins AJ20 and AK21, if one of them is R6 could the other one be the R40 I have left by any chance. I would appreciate a little help please.
Cheers Mike

[Mike Brett]

Finally completed my Sussex board, just the wiring to the sockets to do.

Mike

[Top Cap]

Hi Mike, R6 is important and does indeed go between AJ and AK, it is the lowest current limiting resistor i.e. approximately 5mA unless paralleled with other resistors. The Electrode switch will apply the necessary shunts for R6 such that in A1/A2, R6 is shunted by R7( 10 Ohms now located at Electrode Switch and not alongside R6),R35 (27 Ohms) and R39 (47 Ohms). This gave a current limit of 100mA and later I thought this was a little insufficient and so I changed R35 to 11 Ohms and deleted R39 and gives approximately 120mA.
The other resistors on the Electrode switch come into play on D1 and D2, originally made up of parallel resistors R36 (22 Ohms), R37 (68 Ohms) and R38 (68 Ohms). When I came to wire my Sussex, I decided to stick with just a 2-resistor parallel pair for ease of construction by making R36 and R37 both 27 Ohms and deleting R38. This combination gives an approximate 49mA when the "PUSH FOR 50mA" button is pressed.
I do not know where R40 came in, probably a left over from an earlier BOM.
I have updated the Physical wiring sketch in the guide and added notes to the parts list.
Hope this helps, Les

[Mike Brett]

Les
Thanks for taking the time to explain all that to me, its been a great help. I can now change my resistors to the new values.
Cheers Mike

[Mike Brett]

For the parts of the circuit that require a co-ax cable, I have found a drum of RG174 50 ohm co-ax cable in my spares box. I believe this is rated at 1200 watts at 240 volts. Does anyone know if this would be suitable for the Sussex VT1.
Mike

[ColinTheAmpMan1]

Originally Posted by Mike Brett

For the parts of the circuit that require a co-ax cable, I have found a drum of RG174 50 ohm co-ax cable in my spares box.

Hi Mike,

Is this the kind of 50 ohm co-ax used for aerial downleads? From looking at the specs, it is quite small (2.8mm) in diameter and has a copper-covered solid steel core. I wouldn't use that, as we are not really looking at RF frequencies here, unless I am mistaken, and the solid steel core might break easily when flexed too much. I would use ordinary screened cable with a stranded copper core such as is used for audio leads. It is better to use braided screening, rather than the simpler layered screening, as it is more effective. It won't be terribly expensive from the usual retailers.

Good Luck, Colin.

[Mike Brett]

Yes Colin it is on the small side, that,s why I was not sure if it would be suitable.
Oh well, its audio cable then, pity as I had a drum of the stuff.
Cheers Mike

[Radio Wrangler]

It's 50 Ohm coax, so the capacitance/length is a bit hiigh for the sorts of impedancces used at audio. It's small in order to fit SMA SMB etc connectors.

1200 Watts isn't believable. Huber and Suhner's website is very good for cable specs.

It's probably OK for most things in the Sussex, but not heater connections.

David

[adriaanhendrik]

Originally Posted by G8UWM-MildMartin

I ask any interested parties to contact me to if I may be of assistance

This is my first post on this forum. Although most of my Valve-based stuff is Philips and Telefunken pro-audio, I love the quality that goes with UK Equipment. I have been a 'Homebrewer' for many years now, starting in the 60's

I have read through this amazing thread for a couple of weeks now and decided to take the plunge and build 'The Sussex' myself.
I have bought a couple of transformers with the the right voltages. Good quality switches from Romania and meters from Asia. Still have to decide what case to use, because the switches are a bit bulky.
Now I would like to get the PCB('s). Can I order one please?

Regards

[Mike Brett]

At last, my finished top panel ready for installation. I ended up fitting twelve valve holders, but have also installed an extension fly lead for any future additions that I may need. Fitting the ferrite beads and co-ax cable was very time consuming but probable a necessary evil.

Mike

[mole42uk]

Wow! I only put three valve holders on mine and it still seemed a lot of work!

Richard

[ribbonmicsrus]

I must confess I am only just getting round to building mine, I have all the parts, but can anyone recommend a suitable case/ chassis. I intend to have a large number of valveholders as I restore some pretty old equipment.
Andy

[ribbonmicsrus]

I am looking for the front panel print, the link

http://monopole.ph.qmul.ac.uk/~thoma...frontpanel.htm

does not appear to work, does anyone have another source for this?
Andy