Old vacuum tubes

NOTE: This message is being sent via my ACENET server to my university
address, from whence it will go out on the NEC-LIST. Those of you who
were good enough to pass the original query on to friends and contacts
- please do me the favour of repeating the courtesy. I have to dig
out printouts and pick addresses off those otherwise.

Have a really great day, Duncan.

OLD VACUUM TUBES.
----------------------------

Once again my recent foray into NEC-LIST has confirmed that one does
meet the nicest and most helpful people with this type of query.

I have now acquired these old tubes, and on closer inspection they
really do look primitive. All of them have a central bulbous portion
with two necks at opposite 'sides' of the bulb. Grid and heater wires
enter at one neck, and the anode connection at the other. One of them
has a side connected grid though.

Original responses generally gave the following identifications:

VT4B = 211 Triode
VT30 + 01-A Triode (a rather early triode)
VT31 = 31
and the VT 80 looks like a wrong read in bad light.

There is no evidence of bases at all. All the leads are quite long
wires. Some of the tubes are still in their shipping crates. The
typical suspension wa crossed strips of canvas connected to springs at
the side corners of the crates, or pieces of canvas with holes for the
tube necks. Surprisingly light, simple and rugged - nicely sprung.

Will WOEOM thinks that these may be spare transmit tubes sent to South
Africa in the 20s or 30s. Britain also used the V.T designation, and
from the added description I provided these tubes resemble the Marconi
Osram MT1 or MR1.

John H Walker offered the following:

1) VT4B by Ediswan.

Same as the CV1553, same as ES450X.
Transmitting Triode.
Filament is 18V @ 5.15A
450 Watt Plate dissipation (Pretty helathy jug!)
No base.
Made for the RAF by British Services, which means one of the
British valve makers.

2) VT30 made by STC (Standard Telephone and Cable) for the RAF.

Same as CV1030, same as 4060A
Transmitting Triode
Filament is 12.5V @ 5.5A
250 W plate dissipation.
No base.

3) VT31 made for the RAF by "British Services"

Transmitting Tetrode.
Filament is 11.25 V @ 8 A
250 W plate dissipation
No Base.

John also supplied info on the VT80, which I think I erroneously read
from VT30. The etching on the envelope tends to spread a bit
sometimes.

The info supplied by John is probably the correct data. Certainly the
(presumed) voltages inscribed tie in with his information. Just for
fun, I am supplying dimensions and such etched information as I could
read off the glass envelopes.

I am sure you will all agree that these are interesting specimens of
early valve technology. Come to think of it, they would make really
nice presentation pieces for a number of awards.

1) VT 30 - has the following markings:

"C" with a three piece upwards arrow, all elements the same
length.
TYPE V.T. 30
12.5-250
Ref. No. 10E/8738
Serial No. Of the 3 units available, only one has a serial no.
5430.

Other markings - ESE above 17 inscribed in a circle.
One if the units is also marked EDISWAN, plus a Crown with A.M
below it.

The grid and heater base supports are variously inscribed 19983,
17870 DC, and 2004 LA

This is a triode.

Overall length ~28.5 cm
Diameter glass necks ~5.3 cm
Central spherical bulbous portion ~10.8 cm diametr

2) VT 31 - has the following markings

C with upwards arrow (see 1 above)
V.T. 31
11.25-250
10E/8739
Serial No. 4957
ESE 17, similar to 1 above.

This is a tetrode.

Overall length ~36.1 cm
Diameter bulbous part ~16 cm
Length bulbous part ~ 17 cm
Diameter necks ~6.2 cm

One of the two units has the heater and grid support inscribed
6186 DT.

The other Unit is marked COSSOR, with what looks like 183 over V
inscribed in a circle. The grid/heater support structure is inscribed
with the number 4254. The crate in which this came has a badly worn
serialnumber which looks like CL281D.

3) VT 4.B

Markings are:

EDISWAN
TYPE V.T. 4.B
18-450
Ref. No. 10E/5203
Serial No. 3872.

Other markings are ESE over 17 inscribed in a circle, and a Crown
with A.M. beneath it.

This is a triode with a side connection through the central
bulbous portion for the grid.

Overal length ~31 cm
Diameter bulbous part ~16 cm
Length bulbous part ~ 16 cm
Diameter necks ~ 6.1 cm.

4) The last tube is a puzzler - there are just about no
discernable markings as regards type or manufacturer.

The overall length is ~ 35.5 cm
Diameter bulbous part ~16 cm
Length bulbous part ~16 cm
Diameter necks ~6.1 cm

The one unit has a (serial?) number 13772 engraved on it, while the
grid/heater support has the number 5676 inscribed on it.

The other unit has a (serial?) number 12549, and a number 4504
inscribed on the grid/heater support.

Any information on this tube would be most welcome - even if it
amounts to an informed guess. The tube is similar in size to the VT
31, and may well be the same type.

Well, folks, that's what I finally was able to distill from the
available information. I will try to take photographs for those of
you who are interested in this sort of thing.

I would welcome any further discussion on this topic.

My contact info follows below (I hope).

Duncan Baker.

Please note new office fax number as from end of October 1997 is:
+27 12 362 5000

*********************************************************************
PROF. DUNCAN C. BAKER, DEPT. OF ELECTRICAL AND ELECTRONIC ENGINEERING,
UNIVERSITY OF PRETORIA, PRETORIA, 0002, SOUTH AFRICA.

EDITOR-IN-CHIEF, ACES JOURNAL.

PHONE +27 12 420 2775 (OFFICE), +27 12 47 7480 (HOME)
FAX +27 12 43 3254 (OFFICE), +27 12 348 5314 (HOME)
E-MAIL: DUNCAN.BAKER_at_EE.UP.AC.ZA (PREFERRED ADDRESS)
        d.baker_at_ieee.org (IEEE alias address)
LOCAL STANDARD TIME = UT+2 HOURS
**********************************************************************
Received on Tue Oct 07 1997 - 09:32:57 EDT