Punch data for the SD4 Tetrode-Diode Valve

[Chris55000]

The only available curve for the SD4 gives the anode current for –2.0 V GB as 9.0 mA, and very happily Keith Thrower's Valve Data Book gives the VP13C data as 200 V anode for a current of 9.0 mA @ –2.0 V GB, for which Card 206 has been issued, so it looks like we need Card 206 for the voltage and current punch data!

[stevehertz]

Thanks Chris for your continued help, much appreciated.

[Chris55000]

I'll dig out Cards 149 and 206 tomorrow and issue a revised punch list!

Chris Williams

[Chris55000]

So all together, we need a combination of :–

Card 149 for the heater data ;
Card 157B & C for the diode connections punch data ;
Card 200 for the Anode Voltage, Anode Current and Grid Volts Data ;
The card for the valve isted in Base no. 8 on the B7 Valveholder Connections Chart from the "Wireless World Valve Data Book", 1961 Version!

Chris Williams

[PJL]

Chris, I have reposted my proposed Tetrode card here. The table on the top right has the card hole positions 1-10 as the top row, the corresponding pins for each socket are shown below.

As mentioned in the other thread,
The Dutch version of the SD4 is an E444 with a B6 base whatever that is.
The AVO data does have an E444 Va=200, Vs=90V, Vg=-3, ia=4mA, gm=3mA/V but there is also an E444N which is the same except Va=100V.

The datasheet included in the other thread for Va=200, Vs=100, Vg=-3 would give ia=7mA so I would be inclined to set the test conditions for Vg=-4V and set it so that 2mA is the pass line.

[stevehertz]

So where are we with this? Do we have a consensus for the cards' design or still in disagreement? I'm not in any rush, just trying to mediate! Cheers.

[PJL]

The Diode card based on the TDD4.

[Electronpusher0]

If we cannot reach total consensus and end up with 2 versions of the Tetrode I will punch both and let Steve decide which he prefers.

Peter

[stevehertz]

Originally Posted by Electronpusher0

If we cannot reach total consensus and end up with 2 versions of the Tetrode I will punch both and let Steve decide which he prefers.

Peter

That's very fair of you Peter. However, the problem for me as I see it is I won't be able (or it would be very difficult) to ascertain which design works best because I don't have a NOS SD4 to use as a reference, a benchmark, just well used ones and it's a question of finding out which ones have the best emission. You can't rely on potentially poor or faulty valves for proving the accuracy of a test procedure. As I recall, the HSVT is not recommended to be used for comparing the emission levels of valves due to emission only being measured at one point - or something like that. Perhaps someone can explain that or even correct me if I'm wrong.

If anyone has a NOS SD4 or a known very good one that we could borrow then that would be excellent. Lots of care taken and all expenses paid of course.

Chris, PJL, would a PM exchange between you guys help to reach a consensus?

[PJL]

No guarantees with my cards, I wrote the calculator program in 2006 so long since forgotten the details although I do use it quite often and it seems to work reliably although I did spot a minor issue as B10 (the B row is normally for sg) is used to earth the top cap rather than assign it to sg.

To avoid damaging a valve, you can check a card by simply measuring the voltages on the relevant socket pins without a valve and switched to position 6 .

[PJL]

Chris, this is your project and I have been interfering with it, so I will leave the final decision to you. Feel free to ask any questions as I did spend many many hours analysing the circuit to produce the program and age can't have taken it all?.

[Chris55000]

I'll double check the exact wiring of the valveholders between contacts 1 to 9 on rails A to E, logically, Mullard would have wired Contacts A1, to the valveholder pins 1 etc., but as Peter rightly suggests, Mullard could have done it in a different order, for reasons only known to themselves, for the EL84 (card 635) for example, Peter's replacement card has hole A5 punched and not A7 as would be suggested by the EL84 valve base connections, so even possible that like pins on each valve–holder are not necessarily commoned to the same contact, so me thinks I need to get a new diagram started, and we can work it out from there for definite!

Matters aren't helped by me not being able to locate a tetrode or pentode valve with a basing that corresponds to base No. 8 in the "B7" chart in "Wireless World's" Valve Data book yet!

I definitely would like to know why hole A5 is punched on the EL84 card and not A7 tho', I shall have to see if I can find out when I can get my only battery multimeter repaired!

Chris Williams

[stevehertz]

Thanks Chris. No rush, take your time.

[stevehertz]

Chris, are you able to comment further? Cheers.

[Chris55000]

Still tracing out the valveholder wiring diagram of my unit and until I finish this it's difficult to add anything further at this stage!

Chris Williams

[stevehertz]

No worries Chris, thanks for the update.

[Electronpusher0]

I'm still on standby to make the card.

Peter

[stevehertz]

Thanks Peter. I'd rather wait for this to be sorted out than have to make multiple attempts and waste your time. Ok, it may need a couple of attempts, but ideally it would be nice to get it right first time for everyone's sake.

[stevehertz]

How's investigations going Chris? any luck?

[stevehertz]

I'm still interested in having this card made (and I suspect others too would like such a card), is it possible to achieve a consensus on the card parameters for Peter to work from?