Radios Able To Receive Television Sound

[peter_scott]

You can see the stand alone radio schematic here. The front end of the TV / Radios is slightly different in so far as the vision signal is tapped off to a 45 MHz trf receiver.

Peter

[steve.seven]

Can remember picking up Band 1 CH5 tv sound broadcasts from Wenvoe in the late 1960's on this Marconi 346 radio dating from 1936.

The aerial was a long wire of approx. 30ft long, reception not strong but listenable all the same, a really well made quality EMI set of that period.

Still in daily use for long wave reception of R4.

[rontech]

Originally Posted by radiograham

I have a marconi r/gram dating from 1936 which has tv sound marked on the dial.Cant remember the model no at the moment.

My father had two upmarket radios from the 1937 period. One was a console, Marconi 564; the other an HMV table model 650. Both sets have the same type of electronics with 10 valves. Long, Medium and three short wave bands.

Short wave S3 encompassed the Alexandra Palace TV sound frequencies; I think about 45 MHz.

Here in Southport of course reception was not possible and I recall there were virtually no stations which were received. There were a nunber of strange signals though which I suspect were part of the ongoing war at that period.

A BBC Technical Report ( published in 1945 ) re. the Model 650, remarked on the low sensitivity on short wave band 3

I wondered if this was a design feature to reduce interference from European transmissions given the location of Alexandra Palace.

[julie_m]

What licence would you have needed for a TV sound receiver?

[peter_scott]

For sound only just a radio licence.

Peter

p.s. A clearer view of the HMV advert below.

[turretslug]

Originally Posted by rontech

My father had two upmarket radios from the 1937 period. One was a console, Marconi 564; the other an HMV table model 650. Both sets have the same type of electronics with 10 valves. Long, Medium and three short wave bands.

Short wave S3 encompassed the Alexandra Palace TV sound frequencies; I think about 45 MHz.

Here in Southport of course reception was not possible and I recall there were virtually no stations which were received. There were a nunber of strange signals though which I suspect were part of the ongoing war at that period.

A BBC Technical Report ( published in 1945 ) re. the Model 650, remarked on the low sensitivity on short wave band 3

I wondered if this was a design feature to reduce interference from European transmissions given the location of Alexandra Palace.

I recall reading through that report and thinking that the described sensitivity shortcomings on that highest frequency band were similar to the measured shortcomings of the Marconi CR150 professional receiver on its highest 30-60MHz band (2x EF50 RF, EF50 mixer). I'm sure that the CR150 wouldn't have been consciously de-sensitised on this band, I suspect that it simply reflected the limitations of lower-frequency receiver-type architecture at these frequencies (conventional gang-wafer bandswitching, poor L/C ratio, valve noise (the EF50 mixer was used as a multi-grid with suppressor injection), poor perfomance of relatively high-value rolled-film decouplers at VHF, excess inter-linking lead length and so on). A compounding of effects that meant 25+ MHz performance was really struggling.

These two pre-war sets might have given acceptably good results on the 25-60MHz SW3 when the 11m band was introduced though- I recall a handful of stations with very clear reception when conditions were right.

There were quite a few US HF receivers (both consumer and professional) that stretched into the VHF band, often for 6m amateur coverage- it'd be instructive to know how well they performed.

[peter_scott]

Originally Posted by peter_scott

You can see the stand alone radio schematic here. The front end of the TV / Radios is slightly different in so far as the vision signal is tapped off to a 45 MHz trf receiver.

Peter

I was wrong in suggesting that the tapping was a vision output to the TRF. It was the sound input from the TRF front end.
EMI TV / Radio block diagram below showing separate front ends.

Peter

[emeritus]

It certainly used to be the case that you did not need a TV licence to receive a TV sound on a radio. That was because the statutory definition of television receiving apparatus meant that it had to be capable of both receiving and displaying a TV picture.

However, the statutory definition was amended by the Communications (Television Licencing ) Regulations 2004 (S I 2004 No 692).

Definitions for the purposes of the Communications Act 2003 and the Wireless Telegraphy Act 1967 include the following.

+++++++++++++++++++++++++++++++

Meaning of "television receiver"
9.- (1) In part 4 of the Act (licencing of TV reception), "television receiver" means any apparatus installed or used for the purpose of receiving (whether by means of wireless telegraphy or otherwise) any television programme service , whether or not it is installed or used for any other purpose.

(2) In this regulation, any reference to receiving a television programme service includes a reference to receiving by any means any programme included in that service, where that programme is received at the same time (or virtually the same time) as it is received by members of the public by virtue of its being broadcast or distributed as part of that service.

Meaning of "television set"

11.- (1) In Part 1 of the Wireless Telegraphy Act 1967, "television set" means any apparatus which (either alone or in association with other apparatus) is capable of receiving ( whether by means of wireless telegraphy or otherwise) any television programme service but is not computer apparatus.

++++++++++++++++++++++++++++++++++

Thus the former explicit requirement for displaying a picture has been removed. It is a moot point whether there is an implicit requirement.

The regulations may well have been changed since I looked into this a decade or so ago. I was wondering if a blind person could avoid the need to pay for a TV licence by using a video recorder that was not connected to a TV set to listen to the sound, but it appeared that the change to the statutory definition of television receiving apparatus meant that this might not the case. As it was an academic point I did not make any further enquiries.

[Richard_FM]

Thanks for the feedback, I had seen pictures of 1 or 2 old short wave radios that had TV sound marked on the dial.

[Andrew B]

I have a modern battery transistor radio with TV 2-13 on it, covers from 40 to 130Mhz in 2 bands.It was popular in Colombia, S. America for listening to soap operas as most TV programs contained a lot of verbal exchanges. The terrain made reliable video reception difficult and the electricity supply was unreliable, so enabled people to listen to the telenovelas.

[radiograham]

The r/gram i have is Marconiphone model 363 and it does have tv sound,i must try it one day.

[Dave Moll]

Even people who are registered blind need a television licence (albeit at half-price) to listen to television programmes, so this would clearly indicate that a licence is needed to use such equipment as sound-only receivers.

[peter_scott]

You could argue that the meaning of the word television by definition implies the reception of visual imagery and if you are not receiving this then you are not receiving television.

Peter

[Dave Moll]

You could, but I don't think the Licensing Agency would be convinced!

[raditechman]

Some of the Jason tuners could receive TV sound as well as FM radio They were around during the 1960's.

John

[rontech]

Originally Posted by turretslug

I recall reading through that report and thinking that the described sensitivity shortcomings on that highest frequency band were similar to the measured shortcomings of the Marconi CR150 professional receiver on its highest 30-60MHz band (2x EF50 RF, EF50 mixer). I'm sure that the CR150 wouldn't have been consciously de-sensitised on this band, I suspect that it simply reflected the limitations of lower-frequency receiver-type architecture at these frequencies (conventional gang-wafer bandswitching, poor L/C ratio, valve noise (the EF50 mixer was used as a multi-grid with suppressor injection), poor perfomance of relatively high-value rolled-film decouplers at VHF, excess inter-linking lead length and so on). A compounding of effects that meant 25+ MHz performance was really struggling.

These two pre-war sets might have given acceptably good results on the 25-60MHz SW3 when the 11m band was introduced though- I recall a handful of stations with very clear reception when conditions were right.

There were quite a few US HF receivers (both consumer and professional) that stretched into the VHF band, often for 6m amateur coverage- it'd be instructive to know how well they performed.

Your reference to EF50 valves invoked a memory. Back in about 1956, I had all the constructioal details to build the "Argus" TV receiver using ex WD items. I managed to acquire a British Radar unit with a VCR97 6" green phosphor screen. Also on the chassis were a number of Red Sylvania EF50 metal can RF pentodes. I think the Argus specified these for the primary RF stages and Mazda or military equivalent for the IF's.

Minor issue was the Mazda Octal valve base with these which looked like an I.O. base but wasn't!

[G6Tanuki]

The big issue with early valve VHF receivers was that the effective input impedance of valves-of-the-day was rather low, meaning that the grid-coil was heavily damped, limiting the voltage-swing that could be delivered by a weak input signal. Much of the front-end design effort of the time was to reduce this damping effect - which led to the emergence of RCA's "Acorn" valves in the mid-30s.

The EF50 was a similar effort to reduce this damping-effect, as was Mazda's contemporary SP41/SP61 - both of which gave a respectable performance at frequencies up to 100MHz or so.

Shortly after WWII came the EF54 which had aligned grids and gave greater gain, working reasonably well up to 200MHz.

The modern sound only device is the set top box, I have one with a display so I know which channel I am tuned to (radio, 4 extra in stereo is a bonus). I did ask the "authority" if I needed a TV licence to tune it in (the device is then capable of displaying a picture), they said "yes you do but you could take it next door to set it up". No mention of not being able to listen to TV sound.

All rather academic in the end, I could happily do without a telly but SWMBO loves it.

[Dave Moll]

Interesting that, at least according to your "authority", the salient point seems to be whether the device produces an image - regardless of the ability to see that image.

When I said "tune it in" I was talking about setting up the box to the local multiplexes, this requires an image and hence a telly (hdmi monitor). Using it without a display device was deemed OK licence free.