Pre-war television aerial spotting

[Panrock]

This GEC promotion, directed at dealers, is believed to date from 1939. Note the Television Aerial.

Steve

[Hartley118]

Unusual portrait aspect ratio on that GEC TV.

Martin

[Panrock]

It's a GEC BT0091. This picture is derived from a photocopy provided years ago by Tudor Rees. The screen detail here is whited out and has been lost. It was drawn in again manually (by me!) for the picture which appears on Jon Evans' site.

[peter_scott]

Some mags with aerial articles:

http://www.americanradiohistory.com/...1937-02-UK.pdf
http://www.americanradiohistory.com/...-1937-07-S.pdf
http://www.americanradiohistory.com/...1938-04-UK.pdf
http://www.americanradiohistory.com/...1938-05-UK.pdf
http://www.americanradiohistory.com/...1939-04-UK.pdf

[julie_m]

Originally Posted by Hartley118

Unusual portrait aspect ratio on that GEC TV.

Looks more like part-open doors obscuring part of the screen.

Did anybody ever put up "fake" TV aerials (or, probably, real ones, just not connected to a set .....) to impress the neighbours?

[Jac]

A bit off topic, but the GEC BT0091 looked liked this.

Jac

[Heatercathodeshort]

Sorry Peter, I forgot to post the picture...

[Heatercathodeshort]

Another from W.T. Cocking's 'Television Receiving Equipment' 1940. John.

[peter_scott]

Although Panrock kicked off this thread you may gather that I'm also very interested to see these pre-war aerials.

John, those are really good photos.

Many thanks,

Peter

[Panrock]

Seconded!

I do get the impression that the earliest 'H' aerials always used the 'full' quarter-wavelength spacing between the elements. Am I right that this spacing shrunk later in many post-war aerials? Hopefully not too far OT.... but what effect did this have?

Steve

[Heatercathodeshort]

From the 'Wireless World' May 1937.

[peter_scott]

Another good one!

Peter

[Nuvistor]

Originally Posted by Panrock

Seconded!

I do get the impression that the earliest 'H' aerials always used the 'full' quarter-wavelength spacing between the elements. Am I right that this spacing shrunk later in many post-war aerials? Hopefully not too far OT.... but what effect did this have?

Steve

From what I can find out, the difference in gain is very small from 0.15 to 0.25 wavelength spacing from dipole to reflector. I have not been able to find out any changes this would make to the polar diagram or the impedance match which I presume there will be.

The info will be out there.
Frank

[Heatercathodeshort]

I agree with that Frank. It was probably done to 'clean up' the appearance of the external 'H' aerial more than a technical reason. It certainly was an unwieldy monster in full form! John.

[Viewmaster]

My Avatar has a good one on a nice mast!

[Heatercathodeshort]

Another contribution from the 'Wireless world' May 19th 1938. Taken at the Ideal Home Exhibition. The 'H' aerial can just be seen on the back chimney. The display house is a mock Tudor design that was so popular [and still is] during the inter war years. The theme was 'Ancient and Modern'. Lovely!
If you had been interested in radio and television back in those days it must have been fascinating seeing the first television aerials appear on the roofs.

I live in a rural area that was on the edge of the Alexandra Palace signals. Many of the older locals remember the huge 'H' aerials appearing during the early post war years.

A television and radio shop in Dorking High Street S.J. Clear and Co Ltd [it's still there!] sold many pre war receivers. If only we could see the sales invoices! Regards, John.

[SteveCG]

Re post no. 33

Indeed the biggest change was to the impedance of the overall aerial. A 0.25 wavelength spacing being not far off 70 Ohms, while a 0.15 wavelength was more like 40 Ohms.

I suggest that in the later days when TV receivers had stacks of gain the signal loss due to the impedance mismatch was neglible. However early designs which were more strapped for gain may have been less forgiving when operating 'on the fringe'.

[peter_scott]

As long as the receiver input was matched to the cable I wouldn't have thought that the 40 ohms would have made any reduction.

Peter

[Nuvistor]

Did any of the 0.15 wavelength spacing H aerials use a Delta match to increase the matching impedance to 70-80ohms?
I seem to recall some 3 and 4 element Band 1 aerials with a Delta match but it could be a false memory.
Frank

[Panrock]

Here's another snippet showing a Television Aerial from 1938 or 1939. The set is an Ekco TC103.

Steve