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Rimlock Construction
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05-10-2014, 05:28 PM
A paper from 1946 by Philips describing some of the techniques used to manufacture
rimlock valves etc. http://www.dos4ever.com/EF50/PTT_okt_1946_large_eng.pdf Lawrence.
05-10-2014, 06:28 PM
If they used the same technique for the ECH21 etc I wonder how they made the c & g5 connection to the metal spigot, also presumably the said valve would have been evacuated via the bottom as there is no glass pip on the top of that particular valve.
I found this cutaway drawing of the Philips ECH21 while trawling around but the description is in Dutch I think: http://www.philipsradios.nl/tips-en-truc...vangst.htm Lawrence
Well that answers the evacuation question (PDF) It seems to be a one stop shop for all things ECH21.
Lawrence.
05-10-2014, 06:49 PM
A good question.
By the way, the B40 uses CV302 which theoretically is an ECH22 although I've never found a Datasheet for same, just for CV302. It has a different Pinout so the 'Spigot connection' isn't needed. They do exist, just, and I have a spare - http://www.ebay.co.uk/itm/ECH22-TUBE-CV3...Domain_186&hash=item1e7f9b4d22 Alan 
CV302.pdf (Size: 98.66 KB / Downloads: 29)
05-10-2014, 07:32 PM
That's interesting Alan, similar characteristics to the ECH21, I wonder if they made the gt to g3 connection in the ECH22 internal to save on possible external capacitance effects say when using up to 30 Mhz.
The ECH22 isn't in my valve data book either, my online data search has been fruitless so far except for the pin outs on radiomuseum. Lawrence.
05-10-2014, 07:47 PM
My guess is that the MoD wanted it that way and it really is CV302. ECH22 is just a convenient label.
Maybe I'm wrong and there were lots of them in days gone by. It's certain that it (ECH22) works and is a lot more convenient than special Valve Holders. Alan
05-10-2014, 07:58 PM
I have no first claim to the source below, it tunes around 90 Mhz I think, sure looks like a ECH something, I don't reckon the ECH21 would go that high so maybe it's an ECH22/CV302.
http://downloads.bbc.co.uk/rd/pubs/reports/1951-05.pdf Lawrence.
06-10-2014, 09:12 AM
Details of the Philips locktal types with the suffix "21" are all given in this link, it's an English version from the Philips Technical Library.
http://frank.pocnet.net/sheets/046/suppi...I_1949.pdf For what it's worth I am now thinking that the "21" (Philips) and the "71" (Lorenz) suffixes are just their respective numbering systems as the valves appear so far as I can make out to be identical. Lawrence. |
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