AVO All Frequency Oscillator

[JonSnell]

I purchased two of these Oscillators from a workshop clearance sale, not working.
After a bit of time, they arrived. I removed the two fixing screws, (front panel screws) and one had no valves in it, the other only one.
Sourcing VR-67 valves was easier than anticipated. There are many equivalents; L63, VT154 and CV1067 to name only a few.
I checked the resistor values and to my amazement, they were all still within tolerance! No spares needed there then.
The turret switch assemblies were still sealed from the factory and as the HF range relies on harmonics of lower frequencies, the tuning within the turret case is critical.
.
Powering up the All Wave Oscillators, checking the HT and any smoothing components for ageing, the oscillators burst into life.
Result.
I attach a few photos for your interest.

[JonSnell]

Both All Frequency Oscillators have now gone to collectors.
A few more photos.
Thanks for looking.

[barrymagrec]

Back in 1975 I replaced the smoothing caps on my Dad`s All Wave Oscillator which he acquired in the early forties- checking the calibration on an HP counter the error was less than you could see on the knife edge pointer.

I stlll have it, I think it is still working though not used for some time.

[Al (astral highway)]

Originally Posted by JonSnell

Powering up the All Wave Oscillators, checking the HT and any smoothing components for ageing, the oscillators burst into life.
Result.

Hi there, welcome to the forum.

So did you leave all the OG capacitors in place? It's not clear from your post what restoration or fixes you completed.

I've had a couple of these on the bench in the past. I'm surprised you managed to get all the tuning ranges up to spec as I only found a couple of the lower frequency ones anywhere close to the mark.

[David Simpson]

Good on you Jon, for reminding Forum folk that the AVO AWO is a jolly reliable piece of kit for any vintage enthusiast's workshop. I've had three over the years, and after refurbishment I flogged two to satisfied recipients & have kept one for bench use. Ideal for LW & MW testing & a source of 455/465KHz etc. IF's. Surprisingly stable for their age. I fitted BNC sockets to them, and mine has a BNC Tee which feeds a wee cheapo(Dong Kwang) digital counter & my homebrew RC probe. They will sing away, spot-on 465KHz, for a day without drifting, once warmed up.

Regards, David

[JonSnell]

Originally Posted by astral highway

Hi there, welcome to the forum.

So did you leave all the OG capacitors in place? It's not clear from your post what restoration or fixes you completed.

I've had a couple of these on the bench in the past. I'm surprised you managed to get all the tuning ranges up to spec as I only found a couple of the lower frequency ones anywhere close to the mark.

Thank you
Apart from valves, they are all original. Beeswax 'condensers' in my experience, are very reliable as the wax used does not allow the ingress of moisture. The last faulty wax component was changes for a more modern one and I still use it to remove brass and non ferrous screws from the deep holes in some radio sets. Place a bit of wax on the screwdriver blade, it then sticks to the screw head. Nothing goes to waste in my workshop.

[JonSnell]

Originally Posted by David Simpson

Good on you Jon, for reminding Forum folk that the AVO AWO is a jolly reliable piece of kit for any vintage enthusiast's workshop. I've had three over the years, and after refurbishment I flogged two to satisfied recipients & have kept one for bench use. Ideal for LW & MW testing & a source of 455/465KHz etc. IF's. Surprisingly stable for their age. I fitted BNC sockets to them, and mine has a BNC Tee which feeds a wee cheapo(Dong Kwang) digital counter & my homebrew RC probe. They will sing away, spot-on 465KHz, for a day without drifting, once warmed up.

Regards, David

I was surprised how good it they performed and as you say, set the required frequency and that is it. None of this modern closed lock loop nonsense, no need when a design is perfected.

[Cobaltblue]

I must admit that's at odds with my experience of Wax capacitors.

I don't replace on sight since a small amount of leakage in some locations (such as decoupling) does little harm (except on AVC line)and I am not doing a paid repair/restore.

In some locations they are a real menace such as grid coupling capacitors.

I am generally amazed if a waxy isn't leaking.

Cheers

Mike T

[John M0GLN]

Bought mine about 25 years ago and took it into work to make a calibration chart against their digital frequency counter as I didn't have then, worked through all the ranges firstly by setting the AVO to a frequency counter reading and seeing what the AVO read and then setting the AVO to a scale reading and seeing what the counter read, checked at various setting across all the ranges to give a complete picture, I looked through the results I had written down and then threw them in the bin, they were all so close, like David Simpson I have also fitted a BNC connector.
John

[TowerRadio]

Leaky wax caps(not Hunts) made my AVO test bridge unuseable. I guess in some locations leakage is not so critical.Les