Telephone calls heard on MW!

[Stylo N M]

Hi,
reading a thread today, just reminded me that during the 1980's i remembered hearing one sided telephone conversations, and on one accassion, both sides of the convesation on MW at around the 200 meters end of the scale.

What on earth would be going on to cause this?

Paul.

[paulsherwin]

Probably an analogue cordless phone. They obviously didn't operate in the MW band, but there are a number of circumstances in which you might hear them there.

[Stylo N M]

Yes paul, it did make me wonder if it must have been somewere nearby.

Paul.

[ms660]

I remember picking them up too, just outside the top end of MW on the way to Top band.

Lawrence.

[Tractorfan]

Hi,
I remember that happening too, but somewhere on the short wave band.
I heard a female voice and thought:
1. It seemed a very strong signal and,
2. She sounded just like my wife.
We had a BT Freeway analogue cordless phone and I could only hear one side of the conversation. I think the other side was on VHF?
Cheers, Pete.

[paulsherwin]

I think most of the early ones used 27MHz in one direction and 49MHz in the other.

[Panrock]

From memory, these conversations, or at least one side of them, could be heard around the 180-metre mark - just below the medium wave band - but most receivers wouldn't tune that far.

[G6Tanuki]

Yes, the first-generation analog cordless phones [BT approved!] used frequencies around 1.7MHz for the base-station-to-handset link.

They used 49MHz for the handset-to-base-station. The 'split' was done that way because it meant that the handset could use a ferrite-rod antenna for reception; when taking a call you had to pull out the 'transmit' antenna on the handset.

[The old 1980s TV series "Bread" had the family matriarch who'd pull out such a phone from her housecoat, extend the antenna and answer a call with "HELLO! YES!"]

Very few people understood the uutter insecurity of these phones: I remember listening to my local doctor discussing *very* medical-confidential stuff about patients ... it was also sometimes possible to go up on a high building with such a phone and tune around until you heard a base-station then make calls....

The coming of DECT - with at least superficial security - stopped much of this, though there was the infamous case of the "Squidgy tapes" - https://en.wikipedia.org/wiki/Squidgygate - which from a radio perspective seem seriously flawed, though there *were* unlicensable high-power cordless-phones [popular at the time amongst farmers] that used frequencies around 40 and 73MHz for the two 'ends'.

[mole42uk]

Originally Posted by G6Tanuki

though there *were* unlicensable high-power cordless-phones [popular at the time amongst farmers] that used frequencies around 40 and 73MHz for the two 'ends'.

Yep, we had one of those near Settle with a J-pole on the farmhouse roof and a fibreglass 'twig' on the car roof. Could make actual telephone calls from about 10 miles away. 1990 era, maybe ±5 years.

[Junk Box Nick]

I bought a BT approved one around 1989. There were only six channels available. Someone two offices away had one and guess what - theirs was on the same channel (as I discovered when I could hear their conversations!) - so I returned mine for one on a different channel. Fortunately everyone else in the complex was happy with a standard plug into the wall phone (or had one on the four channels now left) so I had no more difficulty for the (short) time it was in use.

If the phone was close to a domestic receiver it might be possible to hear an receiver image or a spurious emission from the transmitter.

Mine has long since been chucked - a shame as with a tweak I could have had a go at a bit of QRP AM on topband...

[Jon_G4MDC]

Nothing on top band? Listen to the phones instead. Showing your age? And mine!

Later, nothing on 6m? Listen to the baby alarms - now mostly gone thankfully.
I had the ticking clock, sometimes the baby and sometimes what was was going on in the next room... Mic gain much too high.

You only need to hear the ^B^ baby crying!!!
(Apologies to M.Caine CBE)

[Tractorfan]

Hi,
On a similar theme, I remember hearing early analogue mobile cell 'phones on and around 912MHz on my Standard 528 transceiver which had an extended receive capability. I often heard some very intimate conversations , and people giving their credit card details when buying stuff. It's a good job I'm not of a criminal persuasion!
Cheers, Pete.

[emeritus]

I have a "Realistic: Voice of the World" transistor portable that I got from Tandy some years ago, whose medium wave goes up to 1.7MHz, presumably to provide full coverage of the US AM band. I do recall hearing one side of what I now understand must have been a cordless phone coversation at that end of the dial.

[Julesomega]

Originally Posted by Junk Box Nick

Mine has long since been chucked - a shame as with a tweak I could have had a go at a bit of QRP AM on topband...

Actually they were FM

The tx antenna was the phone cable so if it was fed from a pole it would get out surprisingly well with its mW or so

['LIVEWIRE?']

I remember hearing telephone calls on an ordinary radio, somewhere around 1.6-1.7Mhz, IIRC.

[Radio Wrangler]

Early analogue cordless phones (not necessarily approved!) operated in one direction between the top end of medium wave and the bottom end of the 160m amateur band. The dodgy ones had appreciable harmonic content and could be heard clearly in the 80m band. They could be quite distracting if you were hunting QR stations on 3560kHz. Across the other side of Dunfermline a lady could be often heard conversing, making assignations with her fancy-man at S9 fro probably a couple of miles away. They clearly hadn't a clue they were using radio transmitters. Their meeting point was a phone box near the bottom of Garvock hill. All in the mid 80's. No idea who they were, but all the amateurs in the area knew of the goings-on.

And who said nothing happened in Fife?

David

[VT FUSE]

The A41 Manpack radio was very good at catching baby monitors in the 1980's,with its long whip Aerial they could be heard at full readability across town. I did stop monitoring when I chanced upon a regular sked between a young mum and unknown male friend.

The B.T. Freeway that my parents used was a right pain for appearing in places that it shouldn't have.It was a source of happiness when a local lightning strike on a pole killed the base unit one day.

[Panrock]

Someone said these transmissions were actually FM. What would the deviation have been?

[Radio Wrangler]

They were indeed NBFM. Simply because AM transmitters are more difficult than FM ones. With narrow deviation in the 5kHz sort of range, there isn't much 'FM advantage' in S/N over plain AM. They were easily heard on MF simply by slope demodulation, and the transmitters had some residual AM.

It's a sign of the power of modernish technology that so many people can use a radio transmitter without even knowing it. Compare and contrast with all the trouble they had to go to in 'Where Eagles Dare' and the trail of dead bodies, just to get to a transmitter so Broadsword and Danny boy could have a chat....

David

[lesmw0sec]

I recall an amusing incident many years ago when the lines to Droitwich must have got mixed up. We were treated to around ten minutes of private conversation transmitted on 1500 metres!