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Old 28th Jan 2018, 10:20 pm   #1481
Station X
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Default Re: The "Sussex" Homebrew Valve Tester.

Would one of the forum's Sussex experts mind taking a look at post #1 in this thread to see if any changes are needed.

Thanks.
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Old 29th Jan 2018, 12:41 am   #1482
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Default Re: The "Sussex" Homebrew Valve Tester.

It had been my intention to update the manual last year but various domestic matters intervened meaning various projects have been delayed. When I get the opportunity I'll take a look at the latest updates and produce an addendum to the manual.

Keith
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Old 5th Feb 2018, 8:40 am   #1483
ricothebrol
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Default Re: The "Sussex" Homebrew Valve Tester.

Hi folks !

My tube tester is finally up and running. For reminder it's a modded version, which is able to test power tubes as well. I also had to design an "AC to DC" circuit because I couldn't find the right panel meter for gm reading. This was maybe the toughest part as I wasn't too familiar with floating circuits but now it's working great with great precision (I checked the measurements with a scope across the 10R anode resistor to make sure I calibrated my circuit correctly)

That being said, I ran a lot of different tubes in the tester at "typical characteristic" from their datasheet, and I noticed that I keep having low results for the anode current at the specified bias, and also for gm (I generally increase the bias to reach the specified Ia).

As the tester is still in "test" I double check the voltages with my multimeter and they are correct.

So my question is : do tube makers have a tendancy to be over-optimistic about their tube specs ?

Thanx in advance for sharing your experience.

Best regards.

Eric
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Old 29th Mar 2018, 3:58 pm   #1484
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Default Re: The "Sussex" Homebrew Valve Tester.

The excellent info David G4EBT on meter suppliers.

Unfortunately Asia Engineer does not supply to the UK anymore.

There is another supplier on EBay called 365-Bestseller http://stores.ebay.co.uk/365-bestsel...p2047675.l2563
The supply all three meters.

ie
https://www.ebay.co.uk/itm/3-1-2-Blu...wAAOxy7rdRERLb

73's Mike g4wyz
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Old 29th Mar 2018, 8:15 pm   #1485
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Default Re: The "Sussex" Homebrew Valve Tester.

Hi Mike,
I ordered from this seller a couple of weeks back - they were very helpful in making sure I had the right parts (low supply voltage)
Lou
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Old 1st Apr 2018, 6:25 pm   #1486
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Thumbs up Re: The "Sussex" Homebrew Valve Tester.

Hi folks,
To those who have built themselves a Sussex VT1 using the new boards, I have a question that relates to the Voltage Selector switches and the way they are shown in post #1282 on page 65.

The resistors are shown mounted on the opposite side of the little board to the switch and seem a bit vulnerable to being bent over creating faults and shorts. I was thinking if the resistors were mounted on the same side of the board as the switch they would be better protected.

Any thoughts?

Incidentally, I bought my meters from 365-bestseller and had no difficulty. I contacted them to confirm the connections and they replied very quickly with the required information.

Cheers, Alf

Last edited by Alf Fisher; 1st Apr 2018 at 6:35 pm. Reason: Post number added
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Old 1st Apr 2018, 8:02 pm   #1487
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Default Re: The "Sussex" Homebrew Valve Tester.

Hi Alf,
As long as your resistors are small enough to avoid shorting against the front panel, it is your choice.
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Old 4th Apr 2018, 12:27 pm   #1488
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Default Re: The "Sussex" Homebrew Valve Tester.

Quote:
Originally Posted by Alf Fisher View Post
To those who have built themselves a Sussex VT1 using the new boards, I have a question that relates to the Voltage Selector switches and the way they are shown in post #1282 on page 65.

The resistors are shown mounted on the opposite side of the little board to the switch and seem a bit vulnerable to being bent over creating faults and shorts. I was thinking if the resistors were mounted on the same side of the board as the switch they would be better protected.
The most important aspect to follow when mounting the switches has already been mentioned by G8UWM-MildMartin in his previous post, enough distance to the front panel - you could also put a plastic sheet behind the front panel if you wish to mount the resistors on the switch side to increase the isolation to the front panel.

If you are afraid that the resistors should become shorted in any way you can always put a piece of heat shrink tubing around each resistor or put a dab of silicone glue "binding" them together so they can't move.

I tried to place the resistors so that they shouldn't be able to move around if they are soldered tight to the circuit board, you might turn some resistors 180 degrees around so that any pins that could short be moved as far from each other and so that pins that don't matter if they short moves closer (pins already connected on the PCB).

I never did build a Sussex myself but tested the PCBs by placing components on them to make sure that they would work and would be possible to solder and use properly.

/Martin
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Old 6th Apr 2018, 5:08 pm   #1489
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Default Re: The "Sussex" Homebrew Valve Tester.

Hi folks,

Has anyone created a running-out list to show where the connections from the on-board terminal blocks to the transformer and components on the front panel and everything else that isn't on the board.

It would be useful information to include in the construction manual when its updated.

Cheers, Alf
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Old 7th Apr 2018, 11:54 pm   #1490
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Default Re: The "Sussex" Homebrew Valve Tester.

I've just ordered a set of the PCBs, I'm looking forward to an involving project. I can hide in the garage for a while with this one.
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Old 8th Apr 2018, 9:59 am   #1491
David G4EBT
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Default Re: The "Sussex" Homebrew Valve Tester.

Quote:
Originally Posted by G4WYZ MikeyP View Post
The excellent info David G4EBT on meter suppliers.

Unfortunately Asia Engineer does not supply to the UK anymore.

There is another supplier on EBay called 365-Bestseller http://stores.ebay.co.uk/365-bestsel...p2047675.l2563
The supply all three meters.

ie
https://www.ebay.co.uk/itm/3-1-2-Blu...wAAOxy7rdRERLb

73's Mike g4wyz
Just a point worth reiterating, which isn't always made clear in the description of digital panel meters, (whether measuring Voltage or Current), is that the supply which powers the meter must not share a common ground with the circuit being measured. At the link above it does mention that requirement in the description, but not, for example, with the 500V DC one here:

http://vi.vipr.ebaydesc.com/ws/eBayI...1&secureDesc=0

I've no personal experience of the Sussex but discovered this requirement when I built the Capacitor Reformer which initially featured in Radio Bygones, and later in the BVWS Bulletin, the circuit of which had an error showing a common ground. I've mentioned this before but it might be worth reiterating.

Hopefully, when the meters arrive they do have a datasheet, but if anyone is unclear, I've attached a copy of the sheet which came with my meter, and others that I've bought since.

What a wonderful project this has turned out to be, with many stunning examples of completed testers, (many more yet to be finished!), and such commitment by so many forum members in developing the original design.
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Old 9th Apr 2018, 9:13 pm   #1492
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Default Re: The "Sussex" Homebrew Valve Tester.

Thanks for the pic David - mine did not come with any information!
Lou
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Old 9th Apr 2018, 9:56 pm   #1493
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Default Re: The "Sussex" Homebrew Valve Tester.

Could anyone PM me the approximate DC winding resistance and rated current for the 6,3VAC winding. I'm curious as to the feasibility of a low drop out regulator board for the Sussex heater supply.
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Old 19th May 2018, 11:45 am   #1494
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Default Re: The "Sussex" Homebrew Valve Tester.

Some posts moved to a new thread here:-

https://www.vintage-radio.net/forum/...d.php?t=146683
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Old 25th Jul 2018, 6:46 am   #1495
G4WYZ MikeyP
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Default Re: The "Sussex" Homebrew Valve Tester.

The current PCB (c/w daughter board) ie version 9, whats happened to the low voltage function which was available on the original.

Looks like a separate PCB will have to be made, incidentally the Heater select switch quoted in the BOM is wrong it ought to be a 1 Pole 7 Way, not a 2 Pole 6 Way
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Old 25th Jul 2018, 8:34 am   #1496
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Default Re: The "Sussex" Homebrew Valve Tester.

It has been changed from one LM317 switchable between 1.4V and 2V to one for each, sharing a heatsink (so insulating mounting kits are needed).
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Old 23rd Aug 2018, 9:12 pm   #1497
G4WYZ MikeyP
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Default Re: The "Sussex" Homebrew Valve Tester.

In the Commissioning Section of the manual (page 5)

Measure the heater voltages between TB2-2 and TB2-5 and check it is within expected tolerances.

The lowest I can obtain is 7.42volts, using a Rigol DM3058E
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Old 10th Oct 2018, 9:29 am   #1498
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Default Re: The "Sussex" Homebrew Valve Tester.

This is truly excellent valve tester, my observations are the lack of information as the manual in use was written for the original design by Less Carpenter.

The PCB is now on version 9, thanks to the updates by 'Detatron'.

When I started wiring and connecting the PCB all my misgivings evaporated away. The commissioning was excellent as some faults where wring found, unfortunately let down by no mention of setting up the oscillator.

Really impressed, thanks to all who have been involved with this design.

Attached is a 'Bill of Materials for version 9', which includes alternative suppliers and descriptions, if you decide to source from elsewhere.

Photographs will follow.

Mike G4WYZ
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Old 11th Oct 2018, 5:56 pm   #1499
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Default Re: The "Sussex" Homebrew Valve Tester.

I must confess to not keeping up with the changes since I built an early model and it has given faultless operation. The sine wave generator was either a work or no work circuit which seemed to rely on VR1 (200 Ohms) being set to the right point, I added the value that I found to work on mine which was 85 Ohms. Adjusting the 100mV drive, if I may call it that, required a RMS Voltmeter though I did wonder at the time, if it was possible to use the front panel AC mV Meter. Using a switch, one should be able to set the meter to 100mV by VR2 (4k7) then monitor the sense resistor R12 (10 Ohms) as normal, any metering errors will apply to both switch settings and thus give a reasonably accurate gm reading. You would of course have to set the Bias Volts Pot to 0V when checking 'drive' or the AC mV meter may complain. Maybe the switch could be made to do this in the CAL position?

I kept putting off trying this arrangement until the Sussex required service but that has not happened and maybe someone is in a better position to try it. If it works, the CAL pot and switch could be mounted on the front panel close to the sense resistor?
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