Whats this? King VHF Aircraft Transceiver with integrated VOR Receiver.

[electronicskip]

Went to the Beaulieu international Autojumble at the weekend and bought a few radios/transmitters for a few pennies.

But this unit is a bit of a mystery to me.
Its a bit rough but its badged as a KING Nav (i think) KX150E Director.
Has a Pye microphone and a big lump on top of the unit with a retractable aerial unit built in.
For £5 i thought it was worth it just for the mic, but cant really find anything on the net .
I originally thought it might have been a taxi radio as it had to/from on it but I'm thinking it might actually be an aircraft radio.
Any thoughts?

[Station X]

It would be interesting to see inside. Frequencies do sugest an aircraft radio.

[PJL]

https://www.aviationancestry.co.uk/?...=ASC&pageNum=4

[Navigator]

It is the combined King VHF Aircraft Transceiver with integrated VOR Receiver.
In the middle of the frontpanel is the VOR-Indicator located.

Sorry, I was to late to submit this information, PJL did it already.

[Radio Wrangler]

King got absorbed into Bendix and now trade as Bendix-King which is a rather reputable brand in the eyes of pilots and aircraft owners. Bendix is a subsidiary of Honeywell.

The COM radio transceiver is on the left. The outer knob selects one of a bank of crystals to step the frequency in 1MHz steps for the first LO. The inner knob selects one of a bank of 10 crystals for 100kHz steps at teh second LO. 100kHz steps dates it. channels got shrunk 100k, 50k, 25k and very recently 8.333333kHz

The rigght hand side receives navigation signals. VOR for general area navigation, flying a bearing to/from a ground VOR beacon site and also the localiser aspect of the instrument landing system. Coverage is 112 to just under 118MHz. One knob will shift the bearing setting arc above the meter. The meter tells you to fly left/fly right to keep on track. Note it includes flag indicators for to/from.

It might be just the control head rather than the full thing. B-K is still on the go though they've been having other firms do some badge engineering for them. Their latest Mode-S, ADS-B, transponder (KT74) has rather a lot of my work in it.

David

[electronicskip]

What sort of age would it be ? and im guessing the PYE Microphone is non original too?
If its aircraft based, what sort of aeroplanes would use it do you think?

[G6Tanuki]

It's from the 1960s; the nonstandard microphone and home-made diecast-box-on-top [which probably contains a loudspeaker?] suggest that its most-recent use was not in an actual aircraft but as a questionably-certified portable/ground-station.

[Jon_G4MDC]

The ad in Post #3 was 1963...
At the time this would have been expensive and so only well heeled private pilots.

More likely small air operators. I would guess airlines as such would be happy to use separate COM and NAV sets, probably different crew responsible. I don't know...

Pye mic is of the right era - but wrong! My local airfield was still running a Pye Cambridge in the 1990's. Their frequency had never changed so nor had the rig.

[Radio Wrangler]

Commercial operators are fairly happy to use combined nav-com sets. They fit two for back-up. And internally the NAV and COM sections are often kept fairly separate so a common point of failure which takes out both sides is unlikely. Expect individual power supplies.

The microphone does suggest that it was used to transmit, not just a questionably legal eavesdropper.

David

[Richard675]

Being an Air band unit it will be AM

[GMB]

I can tell you that by end of 60's sets like this were pretty standard in light aircraft. I used them all the time.

Also, in the multi-seat aircraft I flew the set didn't really have a microphone of its own as it also provided intercom services. The audio sockets were separate from the set itself and were used with various headsets or sometimes loudspeaker and microphone. The PTT was duplicated on the control column.

The connections to the VOR display also include a squelch flag to indicate that the signal is bad. The selectivity of these sets was not so good in that you could receive the VOR signal while tuned to the adjacent channel so you had to check carefully that it was tuned correctly.

[electronicskip]

Very interesting all around chaps, thank you.
I certainly wont be powering it up, but will go in my Transceiver collection.
It,s typical of the sort of stuff that turns up at Beaulieu.
I also picked up a Midland unit which I thought was another CB radio which turns out not to be, so will open a new thread for it.

[Radio Wrangler]

There is a steady flow of period radio gear from aircraft. From time to time new standards are issued.... more and narrower channels fitted into the band, better selectivity, better rejection of strong broadcast band signals nearby etc. On each of these changes, a date is set and you either replace your radios with something to the new standard or you stop flying. Simple as that. There is no market for keeping using equipment to older radio standards, so the old gear turns into scrap on the magic date.

So while there is a ready supply of historic equipment, it will never be allowed to be used again.

You could use it as a ground receiver for curiosity, but as a lot of radio traffic will be on channels it doesn't have the selectivity to be able to select, nor can it tune to the centre of, it's going to be rather limited. I'm afraid it's really a museum piece and other than curiosity, there isn't much reason for getting it working.

Our firm made a range of modern, certified radios, some to fit the centre panel avionics stack you'll find in Pipers, Cessnas etc, and others designed to work with a tiny control head that fits in a spare instrument sized hole in a panel. These are the sorts of things flying in the holes left behind by the old equipment. The instrument hole ones are popular with people owning vintage warbirds. The RAF Battle of Britain Memorial Flight and other similar groups use them. Becker in Germany make similar radios. There are some from American firms (but are badged engineered ones of ours).

America has just done a major refit of all aircraft transponders. An order was published several years ahead of the magic date. After that date, everything allowed to fly had to have a transponder transmitting position etc data sourced from a certified ($$$$) GPS receiver. There was a significant amount of friction, but it happened. If you consider the number of aircraft in the US, the cost of the new gear plus the installation charges from certified avionics technicians required to certify the installation, you'll arrive at an estimated number telling you how much of a big matter it was.

So the avionics world is very different to other radio services. There is quite a culture shock if you get involved.

David

[electronicskip]

What sort of voltage would it run at?
Ive blown the advert up as it does say but its rather low res and i cant work out if it says 20volts or 28? it might be neither .

[G6Tanuki]

28 v was a standard aircraft power supply. Bigger things like radar tended to use 400 hz three phase AC.

[AC/HL]

Light aircraft are usually 12v, or they were when I was an avionics engineer. There is a manual available here: https://www.ebay.co.uk/itm/123681795354. Only a fiver, but the postage is a killer.

[Walterh]

Hi

As i have a KY95 of the same eara, i scanned the specs, specially concerning supply voltage....

Kind regards, Walter

[buggies]

A few Cessna C172s have a 24 volt battery system.
(Only one out of the four or five I have flown).

[Radio Wrangler]

A lot of the C172s flew with the Bendix King KT76 transponder, a 12v unit. In the 24v planes a 10 Ohm series dropper resistor was fitted somewhere in the power feed to the set. Being a transponder and transmitting <1% of the time in very short bursts, the power consumption was almost fixed (dominated by the thermionic transmitter's heater) so the dropper was fine.

Nowadays, SMPS take care of things by spanning both 12 and 24v ranges. You have to be able to work down to around 9v and to around 40v with surges to 60v and 80v to get certified. But it's not too difficult for receivers and transponders. COM radios have appreciable transmitter power; AM >4W or >16W carrier power so getting on for 16W or 64W PEP. and this means appreciable current from a 12v system at its minimum voltage.

So the higher power radios tend to be 24v and the lower power ones 12-24v

4W is intended to give 100nm range, 16W 200nm. Receiver threshold levels are defined unless you press the squelch open button.

24v planes give you the option of choosing some more serious avionics, retractable gear etc. Quite often 24v planes have a voltage converter to allow the option of some 12v things.

David