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Old 3rd May 2010, 8:35 pm   #341
M0XNA Neil
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Default Re: The "Sussex" Homebrew Valve Tester.

Here are some pictures of my completed 'Sussex in a Suitcase' testing and EL34. The test readings are:

Va = 248V
Ia = 9.1 mA
Vg1 = -18.1V
Gm = 3.01 mA/V

Thanks to Mike's wonderful design I now have a valve tester. Something I thought I would never have due to cost.

I have expanded the suitcase use to include the Fluke 8060A as it can measure true RMS up to 100KHz (C.F. up to 3), dBs of gain and frequency. It is therefore a valve amp 'medical suitcase'!

Here are some pictures.

Neil.
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Old 3rd May 2010, 8:54 pm   #342
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Default Re: The "Sussex" Homebrew Valve Tester.

Hi Neil,
I take my hat off to you, I take it that those are the general purpose multimeters from Maplin or similar? If so, what a great use of these and they are at least two thirds of the price of the ones ordered from China.

Well done indeed.

Regards

Rob
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Old 3rd May 2010, 9:01 pm   #343
M0XNA Neil
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Default Re: The "Sussex" Homebrew Valve Tester.

Rob,

Yes they are indeed those Maplin meters. When I purchased these meters to balance cathode currents in a guitar amp, they were two for a fiver.

Neil.
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Old 5th May 2010, 9:04 pm   #344
M0XNA Neil
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Default Re: The "Sussex" Homebrew Valve Tester.

Does anyone have a soft copy of a valve tester catalogue which states the valve parameters for each valve, including the pin allocations?

thanks,

Neil.
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Old 5th May 2010, 9:24 pm   #345
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Default Re: The "Sussex" Homebrew Valve Tester.

Neil,
Not quite sure what you mean by "soft copy", but you can download the AVO valve data from
ftp://bama.sbc.edu/downloads/avo/vcm-data-new-edition/
For the "Sussex" use the connections for the CT160 - the numbering is the same
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Old 5th May 2010, 10:11 pm   #346
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Default Re: The "Sussex" Homebrew Valve Tester.

Neil,
Site seems to be down, try the mirror
http://bama.edebris.com/manuals/avo/...a-new-edition/
Mike
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Old 5th May 2010, 10:33 pm   #347
M0XNA Neil
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Default Re: The "Sussex" Homebrew Valve Tester.

Mike,

Thanks for the document reference. I have downloaded it from the mirror. Now to test a box full of old valves!

thanks,

Neil.
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Old 6th May 2010, 1:25 am   #348
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Default Re: The "Sussex" Homebrew Valve Tester.

Could someone please take a look at these panel meters and tell me what you think either good or bad ect... LINK > http://www.lightobject.com/3-12-Digi...135-P220.aspx# Thanks Albert
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Old 6th May 2010, 8:35 am   #349
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Default Re: The "Sussex" Homebrew Valve Tester.

Albert,

You need one each of the following;

http://cgi.ebay.com/3-1-2-Blue-LCD-D...item5ad93e752e

http://cgi.ebay.com/3-1-2-Blue-LCD-D...item5ad8f96ec4

http://cgi.ebay.com/3-1-2-Blue-LCD-D...item5ad8f86375

If you email the seller, he'll do you a deal on all three.

Regards

Andy
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Old 6th May 2010, 8:32 pm   #350
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Default Re: The "Sussex" Homebrew Valve Tester.

Just a build update from me.
I've wired the top panel bar one socket which is supposed to be an A08 but doesn't seem to be. I guess I'll have to get another.
I've decided to use a nine way Molex connector 'in the air' to interconnect the panel and the board. I really want to be able to take any panel off completely and easily for service purposes.
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Old 6th May 2010, 8:34 pm   #351
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Default Re: The "Sussex" Homebrew Valve Tester.

I would appreciate if someone could PM me and explain how to attach pictures like these as thumbnails.

Ta
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Old 6th May 2010, 8:40 pm   #352
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Default Re: The "Sussex" Homebrew Valve Tester.

See post #5 in this thread:-

https://www.vintage-radio.net/forum/...ad.php?t=53766
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Old 7th May 2010, 7:43 am   #353
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Default Re: The "Sussex" Homebrew Valve Tester.

Andy, Thank-you for the meter links ! Albert
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Old 8th May 2010, 8:13 pm   #354
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Default Re: The "Sussex" Homebrew Valve Tester.

Quote:
Originally Posted by thor1961 View Post
Could someone please take a look at these panel meters and tell me what you think either good or bad ect... LINK > http://www.lightobject.com/3-12-Digi...135-P220.aspx# Thanks Albert
Bear in mind that the one you mentioned is powered by DC only, whereas the other ones listed by Andy, which are from Asian Engineer via e-bay, can be powered from 9 - 15V ac or dc.

A small point perhaps, but as an earlier post mentioned, the modest power requirements of these meters means that they can e powered from a few turns each overwound on a transformer (each needing a separate power supply, and must not share a common ground).

Sure, a DC powered meter would only need a rectifier diode, but if ac powered meters are used, it saves a small complication. I've had several meters from Asia Engineer - modestly priced, excellent service, and they work well.

Best of luck to Sussex builders - good to see that some projects are coming to fruition!

David.
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Old 9th May 2010, 1:17 pm   #355
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Default Re: The "Sussex" Homebrew Valve Tester.

David, Thank-you for your post, I was originally a little weary about using what looked like low grade mass production stuff. The meters in my post use a "Intresil 7106/7 chip" and seem and/or appear to be built to a more industrial standard, though more complex and expensive to implement. If you and others have had good luck, I should probably order a extra set in the event they fail prematurely or become discontinued ect... For what its worth I've always believed that quality is not cheap and cheap is not quality ! With electronics I tend to over-build many things because I lack a great deal of knowledge and/or the needed experience. Again thank-you Albert See link > http://www.lightobject.com/3-12-Digi...135-P192.aspx#

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Old 15th May 2010, 9:59 pm   #356
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Default Re: The "Sussex" Homebrew Valve Tester.

After much searching and various inquiries it seems the "ASIA ENGINEER" meters simply are the best solution ! I really did hope to find a meter with a LED as opposed to a LCD type display. Sorry for the above post and/or any related confusion.
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Old 17th May 2010, 7:25 pm   #357
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Default Re: The "Sussex" Homebrew Valve Tester.

A heater supply for "D" series valves from Ed's transformer at no extra cost?

I am just thinking out loud here and haven't tried this.
Between the 5 volt tap and the 6.3 volt tap on the heater winding there's 1.3 volts. "D" series valves don't draw much heater or anode current and wouldn't load the transformer much, so it would be reasonable to expect that there would be a little over 1.3 volts across the 5 and 6.3 volt taps.
I think most that are building the "Sussex" are using a 2 pole 6 way switch for heater voltage switching.
There is a position on the switch not used and the pole that is not used can be used to switch between the 0V tap and 5V tap.

I have posted a diagram of the switch and heater winding. I think that it probably would work but the voltage across those two taps would need to be checked to ensure that it is not too high.

Frank
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Old 17th May 2010, 10:42 pm   #358
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Default Re: The "Sussex" Homebrew Valve Tester.

Frank,
Talk about lateral thinking, that idea is brilliant. You will however have to fit a switch shorting one side of the heater to cathode, or else you wont get any anode current.
Another problem, is that the Gm wont work, you will be effectively putting a 50hZ signal on the cathode which will modulate the anode current, and the Gm meter will read that as Gm.
I think that if you can arrange for some sort of rectifier/smoothing to be applied the Gm meter will then read correctly, perhaps even further lateral thinking!!

Good luck to all builders, so far one completed shown, how many more are nearing completion.

Regards
Mike
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Old 17th May 2010, 10:53 pm   #359
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Default Re: The "Sussex" Homebrew Valve Tester.

Mike,
I'm not far off.
I got a nice lump of aluminium to bolt the BUZ80's onto, unfortunately I can't find the trsnsistors. I did buy them, but I've misplaced the damn things. I ordered another set and the seller sent me one as the AFI version (ISOWATT220) which isn't really much use as its rated current is about 50% of the standard at 100C.
Won't be long I hope but waiting for the odd bits and pieces to arrive is quite frustrating!!

Regards

Andy
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Old 17th May 2010, 11:21 pm   #360
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Default Re: The "Sussex" Homebrew Valve Tester.

Hi Mike,
I'm now busily working on the case which I intend to finish this week if I can and then I'll press on with wiring the switches etc.


Rob
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