Admirable AVO

[marconi]

When a relative’s husband died and she cleared out her loft she found an old AVO in a leather box. I don’t know how old it is but know it has not been used since her husband left the RAF In the 1950’s. ( I think it may actually belong to them!) It needed a good home so I was given it. I have not got round to cleaning it up and sorting out the missing batteries and it has just sat on the corner of my bench. Yesterday I needed an old fashioned moving coil meter to observe a voltage variation. I compared its output against my trusty skytronics DVM and to my pleasant surprise observed what I recorded in the attachment. Please excuse some of the camerawork. I guess it must be 60 to 70 years old.

ps: My first meter bought as a Christmas present in 1971 which my father was told was the Japanese equivalent of an AVO. It certainly gave sterling service until the rotary switch wore out.

Analog Multimeter TMK-500 Equipment TMK, Tachikawa Radio - https://www.radiomuseum.org/r/tmk_analog_multimeter_tmk_500.html

 

[Lucien Nunes]

pickled in brine

Formaldehyde, probably. Or stuffed. One hunched over a hole in the skirting stripping VIR singles, another with a wooden-handled screwdriver wiring a pendant with maroon twisted twin. Display titled 'Fitting the Electric Light c.1930'

 

[telectrix]

Formaldehyde, probably. Or stuffed. One hunched over a hole in the skirting stripping VIR singles, another with a wooden-handled screwdriver wiring a pendant with maroon twisted twin. Display titled 'Fitting the Electric Light c.1930'

can tell who's who from that. I can't get on my bad knees and pete can't climb. means we need to pay 2 apprentices out of pensions (that's if there's a bit left over from the beer kitty).

 

[pc1966]

Testing audio valves on the dining room table, a while back:

KT66 or KT88?

 

[Lucien Nunes]

Mostly KT66, although it looks like there are a few KT88s at the back (with the metal bases). I can see also a bunch of 5U4s, 6SN7s and various odds. The VCM is now in the museum workshop area and I am supposed to be testing some 1930s US audio triodes for someone, but it's proving an uphill struggle to get me, the valves and the tester together for long enough.

For the younger readers, valves are what we used before transistors as the main active component of all electronics. They were generally quite reliable and rarely needed replacing in ordinary applications; many valve radios for example are still working with all their original valves despite having needed most of their capacitors changed. But valves can and do fail especially if there are faulty capacitors in their surrounding circuitry that drive the valves into overload, and eventually wear out if used heavily. Valve behaviour is quite complex and there are many different kinds with vastly different specs, hence the rather elaborate machine needed to test them properly.

 

[pc1966]

They were generally quite reliable and rarely needed replacing in ordinary applications; many valve radios for example are still working with all their original valves despite having needed most of their capacitors changed.

The two Voyager craft use valves for the transmitters (X-band TWTs) and they are both still working after 43 years of continuous use under "interesting" conditions!

 

[telectrix]

The two Voyager craft use valves for the transmitters (X-band TWTs) and they are both still working after 43 years of continuous use under "interesting" conditions!

so you watched Star Trek The Movie as well?

 

[DPG]

Believe it or not, even into the 2000s many of the police radio transmitter sites were still using an RF transmitter with a valve as the final amplifier. Didn't look very 'valvey' though as it was sleeved with a metal heatsink. Can't remember the type.

This was prior to the Airwave digital system being installed.

 

[Lucien Nunes]

Nothing wrong with valves, still a popular technology; you've got one in your kitchen.

I have a couple of big'uns that you might have had some use out of without knowing it. Prior to the digital switchover in 2012, if you watched BBC1 on analogue in London / South East the signal was coming from a pair of 40kW Harris Sigma transmitters. It was the control unit for those that we saw Mark Thompson switch off ceremonially to mark the end of 75 years of analogue TV in London.

You might be able to guess where one of the transmitters ended up. They didn't let me take the mast, apparently that's still in use.

London analogue TV signal switched off

Analogue television is switched off in London, 75 years after it was first invented.

www.bbc.co.uk

 

[Zerax]

We're not married, but in any case this pic is an old one, taken before we met.

Managed to find a pic of the same dining room shortly after they met...

 

[telectrix]

Managed to find a pic of the same dining room shortly after they met...

that's nothing. my missus insists on placing a vase of flowers or some other tat directly in front of the TV's remote sensor, so you need to be a contortionist with the hand unit. then says it's my fault she can't switch from Emmeroids to Eastidiots, to Constipation Street.

 

[Lister1987]

no bloody chance. he'd have us pickled in brine and put on display in his museum.

Surely your brain already pickled Tel?

 

[telectrix]

Surely your brain already pickled Tel?

brain was pickled in 1975 ( i got wedded to the Poison Dwarf). OK now she's long since gone. brain back to normal state of useless.

 

[Lister1987]

brain was pickled in 1975 ( i got wedded to the Poison Dwarf). OK now she's long since gone. brain back to normal state of useless.

I wouldn't say that Tel, "I'm not completely useless, I serve as a shining beacon in how NOT to do things"
?

 

[Mike Johnson]

We're not married, but in any case this pic is an old one, taken before we met.

I don't think any self respecting woman would have put those curtain up. ?

 

[telectrix]

maybe it was a condition of sale thea the buyer took them off of the vendor's hands.