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Old 13th Mar 2017, 4:37 pm   #1401
AC/HL
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Default Re: The "Sussex" Homebrew Valve Tester.

https://www.vintage-radio.net/forum/...ad.php?t=77650
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Old 14th Mar 2017, 9:22 am   #1402
George G4EUF
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Default Re: The "Sussex" Homebrew Valve Tester.

Many thanks Bill.
George.
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Old 14th Mar 2017, 4:24 pm   #1403
George G4EUF
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Default Re: The "Sussex" Homebrew Valve Tester.

My thanks to you as well Sam.
Regards.
George.
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Old 14th Mar 2017, 4:43 pm   #1404
George G4EUF
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Default Re: The "Sussex" Homebrew Valve Tester.

I have recently noticed that there are now two diodes across R12 in the circuit diagram, was this to give some extra protection to the GM meter?
With my tester I appear to get rather high GM readings, any suggestions?
George.
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Old 14th Mar 2017, 10:56 pm   #1405
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Default Re: The "Sussex" Homebrew Valve Tester.

Have you fitted R6 on the PCB - it's not shown on the layout on P26 of the manual - assuming you are using the original board layout. The holes are there between AJ & AK - top right of the drawing.

Have you checked the audio osc output level that feeds to the grid?

The extra diode added in series with D16 was fitted for a reason, but I can't remember why now, but it's described somewhere - found it on page 23.
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Old 16th Mar 2017, 9:27 am   #1406
George G4EUF
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Default Re: The "Sussex" Homebrew Valve Tester.

Many thanks vidjoman for that, will take a look but almost certain R6 would have been fitted.
The osc O/P has been set to the correct level when I first set up the neg supply circuit.
Putting another diode in series with D16 will require a bigger voltage across R12 before conducting, sounds obvious I know, but will put another one in series and see.
Again thank you.
George.
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Old 16th Mar 2017, 9:33 am   #1407
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Default Re: The "Sussex" Homebrew Valve Tester.

My version of Mike Rowes "Sussex"
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Old 21st Mar 2017, 9:15 am   #1408
George G4EUF
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Default Re: The "Sussex" Homebrew Valve Tester.

Sorry, worded that wrong should be a bigger voltage across the diodes in order for the two to conduct, must be my age !!
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Old 30th Mar 2017, 12:37 am   #1409
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Default Re: The "Sussex" Homebrew Valve Tester.

Hello, I've recently (about 3/15/2017) received the latest version of the main circuit board from Martin (thank you Martin) and I'm having difficulties locating the value of C15. I'm not finding C15 in the parts list or schematic.

Also, are there any known issues with the latest version of the main PCB that will need correction when I'm populating the board?

Thank you,

Dave Bacon
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Old 31st Mar 2017, 2:11 am   #1410
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Default Re: The "Sussex" Homebrew Valve Tester.

Hi Everyone, concerning my recent post (#1409) about C15 on the main PCB, I also checked with Martin C. on this and his very helpful reply was that C15, R102 (which I was also wondering about), and D17, "are the snubber components across the HT relay (RL1) contacts introduced in post #1308.

Martin C. continued to mention that "A resistor of some 390 Ohm, a capacitor of some 220nF @ 630V or 1kV and a diode like UF4007 (or some better diode with higher current
rating) will work fine for this snubber."

Martin C. also reports that "They are optional and there have been no problems reported on earlier issue boards which didn't have them."

To be honest, as a novice electronics hobbyist I had never heard of a "snubber circuit" before but found this very helpful site explaining how snubber circuits are used to protect relay contacts. (A perfect learning opportunity for me)

http://www.hiquel.com/fileadmin/user...te_EN_0100.pdf

I'm making excellent progress towards gathering all of the components for my Sussex Valve Tester build. My goal for this build is not only to have my own valve tester, but to also increase my knowledge about electronics and valve (vacuum tube) theory.

Take care,

Dave
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Old 4th Apr 2017, 2:04 pm   #1411
George G4EUF
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Default Re: The "Sussex" Homebrew Valve Tester.

Hello Dave,
A snubber should always be used when relays are switching inductive loads.
Hope the building of the "Sussex" is continuing well, very much enjoyed building my version of Mike Rowes design and the help I received from "topcap" and others.
George.
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Old 6th Apr 2017, 10:54 am   #1412
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Default Re: The "Sussex" Homebrew Valve Tester.

Hello everyone,
My name is György Szabó, you can call me George. I live in Norway. I've recently found this forum and I'm very happy about it. I have to give respect to the author and say thank to you guys for developing such a useful instrument.
I have read the thread and all available docs so will begin to build the tester in a short time. I have seen many of you has built this tester and all of them has a different look. I understand that everyone has it's own needs/possibilities in design. But I have to ask, is there a need for a more or less standardized design of the front panel for this tube tester? I mean an aluminium sheet panel with all the sockets and controls installed on it. Of course with some extra space for installing extra sockets/controls if needed. A simple design in DXF can be made in a short time. I have a homemade CNC machine which can drill/mill soft metals e.g. aluminium (beside wood) and I have successfully machined a few top panels for my tube amplifiers. I'm going to build this tube tester and I would like to make a nice front panel to have a look similar to a Heathkit or Hickok for example and I want to share it with you. But in order to be useful for others as well I want to discuss it with you and make it maximum usable not only for my needs.
So what you think about this? Is it worth discussion?

'73
George, LB4IG
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Old 7th Apr 2017, 7:53 am   #1413
George G4EUF
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Default Re: The "Sussex" Homebrew Valve Tester.

You have a very famous surname, I wonder if you were related to Violette?
Regards.
George.
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Old 7th Apr 2017, 8:07 am   #1414
mole42uk
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Default Re: The "Sussex" Homebrew Valve Tester.

Personally, I feel that the Sussex can be built to suit the needs of each individual. That is one big advantage. My own has only three sockets because I really only test audio valves, so I don't need to have the facility for a greater range.

Similarly, the layout of the panel is up to the builder's own preference and resources. Mine, a photograph of which is in the User Manual, was rather determined by a 3U rackmount case I had to spare, so everything is built so that the controls are on the front panel and the valve bases are on the top. The top panel is large enough to punch for new sockets if I need to at a later date.
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Old 7th Apr 2017, 1:00 pm   #1415
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Default Re: The "Sussex" Homebrew Valve Tester.

Quote:
Originally Posted by George G4EUF View Post
You have a very famous surname, I wonder if you were related to Violette?
We are a bit off topic
It is a hungarian surname. The exact translation is Tailor (like the profession).
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Old 3rd May 2017, 8:01 pm   #1416
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Default Re: The "Sussex" Homebrew Valve Tester.

Hi, I am having a problem testing a PX4 valve on my Sussex. I have not tested a directly heated valve before so maybe it's me doing something silly.

I connect the ext-heater -ve terminal to the cathode and then connect up the valve as normal. But I am getting massively off readings like Gm=100 and Ia=80mA I am expecting something like 40mA and 6.

Any ideas?
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Old 5th May 2017, 2:47 am   #1417
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Default Re: The "Sussex" Homebrew Valve Tester.

With a directly heated valve you have to run the heaters from DC. Use an external DC power supply giving 4V at 1 Amp. You must use the jumper of course between ext-heater -ve terminal and the cathode.
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Old 5th May 2017, 1:01 pm   #1418
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Default Re: The "Sussex" Homebrew Valve Tester.

Hi Top Cap, glad you were looking! Yes of course that helps and now I get sane results.

I have never come across directly heated valves so it is probably just my ignorance. But I wonder if this is worth clarifying in the Sussex manual?

In the valve testing steps (pg 47) perhaps it would clarify by separating by direct from indirect?
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Old 5th May 2017, 6:36 pm   #1419
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Default Re: The "Sussex" Homebrew Valve Tester.

Good point. I'm planning a manual update soon so I'll incorporate that information.

Keith
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Old 23rd May 2017, 9:08 pm   #1420
Barryg4
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Default Re: The "Sussex" Homebrew Valve Tester.

This may be of interest to builders of the VT1 The oscillator in mine varied from 100mV to about 160 mV on warm up. Looking at the oscillator circuit I was puzzled by the inclusion of D6 - it was not needed for the phase shift oscillator to function. Warming it caused the oscillator output to increase quite considerably, so I decided to remove it. This improved the regulation but it was still not satisfactory. I then decided to reverse this diode and found that my oscillator did not vary at all from the 100mV setting even from a cold start.
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