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Old 10th Jan 2018, 10:17 am   #1461
John G8MWF
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Default Re: The "Sussex" Homebrew Valve Tester.

I think I would like to go ahead with the later one - how do I order/pay for them?

John
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Old 10th Jan 2018, 7:08 pm   #1462
G8UWM-MildMartin
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Default Re: The "Sussex" Homebrew Valve Tester.

PM sent.
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Old 10th Jan 2018, 7:41 pm   #1463
John G8MWF
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Default Re: The "Sussex" Homebrew Valve Tester.

Quote:
Originally Posted by Ed_Dinning View Post
Hi Folks, Sussex transformers are still available and are wound to order. PM me if you need one and I'll get it wound on my return.
Hello Ed,

I am going to build the tester designed by Martin in Sweden - will this transformer be suitable , if it is, how much is it and how do I order/pay for it?

Kind regards

John
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Old 10th Jan 2018, 11:00 pm   #1464
Ed_Dinning
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Default Re: The "Sussex" Homebrew Valve Tester.

Hi John, you have a PM

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Old 11th Jan 2018, 6:18 am   #1465
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Default Re: The "Sussex" Homebrew Valve Tester.

Quote:
John G8MWF wrote: I am going to build the tester designed by Martin in Sweden ....
I feel a correction is in place here, I did not design this tester, "swordholder" did, I just made the latest iteration of PCBs available
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Old 19th Jan 2018, 10:59 pm   #1466
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Default Re: The "Sussex" Homebrew Valve Tester.

Hi Martin (Dekatron),
I have just bought a set of boards from G8UWM and I have to say that they are beautifully made.

Do you have a component listing for your latest edition of the main board as shown in post #1456?

I like the idea of separate regulators for the 1.4 and 2 volt supplies. After a lot of use, I can see intermittent and noisy switch contacts could cause the 1.4 volts to jump up to 2 volts.
Have you considered running these regulators from the 4v or 5 volt tapping instead of the 12 volt one? I think it could reduce the power dissipation in the LM317 by quite a lot.

Alf
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Old 21st Jan 2018, 4:28 pm   #1467
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Default Re: The "Sussex" Homebrew Valve Tester.

Thanks Alf!

You should be able to use both the original component list plus the extra component list for the small LR8 PCB I made, I used the same component numbers on the combined main PCB (unless I made some error).

Since I am not the designer of this tester and neither have I read all of the posts in this thread so I can't say anything on the voltage regulators for the 1.4V and 2V. Maybe someone else can step in here?
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Old 21st Jan 2018, 7:38 pm   #1468
Alf Fisher
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Default Re: The "Sussex" Homebrew Valve Tester.

Hi Martin,
Thanks for the info. I'm now at the shopping list stage.
I've just been researching and finding a source for the bridge rectifiers you've used. The pitch of the lead out wires is 3.8mm or 0.15" and there are many that won't fit but I have found some! I've also found some relays on eBay.

If I am correct, I reckon you might only need the capacitor C1 on the HT Anode switch PCB as the HT feeds for the Anode switch supply and the Screen switch supply are in parallel. Just not sure what value it is as there is already a C1 (100uF) on the main PCB and I wouldn't have thought its value needs to be that big. Any thoughts?

The rotary switches come with skinny spills meant for PCB mounting and there are others with tags for wiring. I guess you could cut off the end of the tag to make them fit the holes.
Cheers,

Alf
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Old 23rd Jan 2018, 3:25 pm   #1469
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Default Re: The "Sussex" Homebrew Valve Tester.

I can answer/comment on two of your questions/comments.

The bridge rectifiers I use are made by Vishay and are from the 2KBP-series.

You can cut off the pins on rotary switches with solder lugs but I have destroyed two switches that way, the pins got lose internally and it was not possible to get good contact later, the pins will also be a lot shorter and that might affect the plastic when soldering them, melting the plastic.

I canít really comment on the reservoir capacitors but I think it is a small cost of ordering one extra.
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Old 23rd Jan 2018, 5:40 pm   #1470
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Default Re: The "Sussex" Homebrew Valve Tester.

Hello,

The main schematic in the Sussex manual shows C13 (22uF 400V) connected to the Anode rotary switch. But there is no capacitor indicated on the Screen rotary switch.

Since both switches (Anode and Screen) are basically configured with identical components (except for C13) I too was confused by the capacitor location "C1" indicated on both of the Anode and Screen switch PCBs. But I agree with Alf Fisher's HT feed comment above (#1468) that only one capacitor may be needed. I also assumed that it's simply easier to use the same switch PCB on both switches (Anode and Screen) rather than design and produce one without the capacitor.

But I do have a question that I hope can be answered...

The MAIN PCB does have a location for a C13. Is C13 on the main PCB simply an optional location for the Anode "C1" capacitor? Or should a capacitor be placed at both locations (C13 on the main PCB AND C1 on the Anode switch PCB)?

Also, if C1 on the Anode switch PCB is needed, what value should it be? I've looked through the forum and haven't found any reference to the value of C1 on the Anode switch PCB.

Thank you,

Dave
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Old 23rd Jan 2018, 6:25 pm   #1471
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Default Re: The "Sussex" Homebrew Valve Tester.

C13 was originally placed across the Anode switch, but due to the way Designspark works with split designs it couldn't handle this and I forgot to change the number of the capacitor across the Anode switch. The original schematic shows C13 as 22uF/400V across the Anode switch.

C13 on newer boards is now an extra capacitor across C3 in the oscillator circuit as I had discussions with some people on the instability of the oscillator. That led to adding an extra decoupling capacitor in the oscillator circuit. You can use a few hundred nanofarads here with a working voltage of some 16V or so (the zener regulates the voltage to 8.2V). Designspark again automatically numbered it C13 even if a new number would have been better, yet another mistake on my part unfortunately.

Taking a closer look at the original schematic I see that the capacitor (C13) on the Anode switch is actually situated on the output of the voltage regulator with the MPSA92 (later on the output of the LR8) regulator - in the case of the circuit with the MPSA92 it is needed to stabilise the voltage across the switches, or rather the output of the regulator, it could probably have been moved to the main PCB but I didn't check that when I made the first pcb version. In the case with the LR8 there is an extra capacitor in the circuit, C16, which stabilises the output of the LR8 so in that case the capacitor across the Anode switch can be left out of the circuit even if it doesn't hurt if it is left in place.
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Old 24th Jan 2018, 12:14 am   #1472
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Default Re: The "Sussex" Homebrew Valve Tester.

Martin,

Thank you for replying to my previous post (#1470) concerning C13 on the main PCB and C1 on the Anode switch PCB.

Based on your recommendations I'll go ahead and use a 300nF 16V (or so) capacitor on the Main PCB at location C13.

And since I plan to integrate the new LR8 voltage regulator design (post #1441) on my older Main PCB I won't use the 22uF 400V capacitor (C1) on the Anode rotary switch PCB.

And finally, a huge thank you to you and everyone else for their continuing work and support on the Sussex Valve Tester project.

Take care,

Dave
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Old 25th Jan 2018, 3:11 am   #1473
DaveBacon
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Default Re: The "Sussex" Homebrew Valve Tester.

Hello,

When comparing the "Sussex new board Components" parts listing for the main PCB with the PCB I noticed that the PCB has a place for C106. But I'm not able to locate a value for C106 in the parts listing.

I'm assuming C106 will be the same value as C105 (100nF 63V Poly Box) but I thought I should check with the forum to make sure.

Thank you,

Dave
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Old 25th Jan 2018, 7:12 pm   #1474
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Default Re: The "Sussex" Homebrew Valve Tester.

If you check the new circuit diagram you see C106 on the output on one of the LM317, so 100nF@25V is good enough there as it is only for decoupling purposes.
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Old 25th Jan 2018, 11:41 pm   #1475
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Default Re: The "Sussex" Homebrew Valve Tester.

Thank you again Martin. Much appreciated.

Dave
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Old 27th Jan 2018, 4:15 am   #1476
DaveBacon
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Default Re: The "Sussex" Homebrew Valve Tester.

Hello,

Are the following resistor values still correct for the Electrode Switch PCB?

R7 = 10R
R35 = 27R
R36 = 22R
R37 = 68R
R38 = 68R
R39 = 47R

I'm struggling trying to locate a current parts listing that includes all of the resistor values for the Electrode Switch PCB.

The above values are taken from Page 13 of the Sussex Valve Tester Construction Manual (1st edition May 2014).

Thank you

Dave
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Old 27th Jan 2018, 12:38 pm   #1477
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Default Re: The "Sussex" Homebrew Valve Tester.

I made a new set of schematics today for the LR8 version plus the switches where I included the component values on the drawing, I did my best to check the component values against the original but please double check them against the original schematic.
Attached Files
File Type: pdf Sussex-PCB-V9-LR8-BOM.pdf (96.9 KB, 245 views)
File Type: pdf Sussex-SWITCH-PCB-V4-BOM.pdf (19.1 KB, 164 views)
File Type: pdf Sussex-ELECTRODE-PCB-V4-BOM.pdf (16.0 KB, 168 views)
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Old 28th Jan 2018, 8:49 pm   #1478
DaveBacon
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Default Re: The "Sussex" Homebrew Valve Tester.

Hi Martin. Your updated drawings for the Anode/Screen switch PCB and for the Electrode PCB look very good to me.

I've sent you an email asking if you have any of the new V9-LR8 main PCBs available for purchase.

Thank you for all the time you put in to updating the PCB schematics to include the BOM.

Dave
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Old 28th Jan 2018, 9:48 pm   #1479
Dekatron
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Default Re: The "Sussex" Homebrew Valve Tester.

DaveBacon, I Dekatron (Martin in Sweden) don't have any PCBs I just made the first editions which I then shipped to G8UWM-MildMartin in the UK, so you should ask G8UWM-MildMartin (Martin in UK) who Might have some.
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Old 28th Jan 2018, 9:58 pm   #1480
G8UWM-MildMartin
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Default Re: The "Sussex" Homebrew Valve Tester.

I still have 7 or 8 of Martin's second batch (the ones with extra holes for different pots. and caps.) left and regret I will only order the latest design when down to the last one or two, which may take a year at current sales rates.
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