I've just finished recapping an AWA 467. Testing of the 6BV7 showed so many different shorts, about four in all, that I didn't bother trying it in the radio and scrounged around my spares finding two. One tested extremely good but turned out to have a very intermittent plate short that drew an alarming amount of current, the other had very weak diodes. Although the detector diode worked okay in the radio the AGC diode didn't work at all well.

No problem I thought, I've got a couple of AWA 449's on the shelf awaiting recapping. No good here either, both of these valves have various issues.

To me at least 6BV7's seem to be an incredibly unreliable valve or prone to wear and possibly the reason a lot of these old radios were put out to pasture in the first place. Has anyone else struck problems with these?

I'm also on the lookout for a couple of 6BV7's, considering recent experience, NOS is probably a good idea

Warren

Yes, I've found them to be incredibly unreliable too. I was lucky to find a good one when I recently restored a 467MA for a mate.

Does any one know if you could replace a 6BV7 with a 6BQ5 and a couple of germanium signal diodes? Of course I understand you would have to re-wire the socket.
I've looked at the valve specs and the 6BQ5 looks fairly close to the pentode section of a 6BV7.

If you are considering rewire & diodes 6M5 was fairly popular and is the pentode in a few other valves. You would need to change the cathode resistor.

There is a horizontal op valve that you can sub for a 6M5 but you must wire pin 6 to the cathode as the suppressor is not internally connected on the TV tube.

Dear Scraps.

Are the 6BV7's you are having difficulty with, of the construction of looking as though the valve itself was placed onto a "pre-made base assembly" (base/pins)?

The base of the valve was quite square and not rounded like any other nine pin noval base.

Valves of this construction, (very common in Astor radios) were prone to a phenomenon known as metal migration. The potential difference, (voltage), between the pins would cause traces of metal to migrate between pins (outside the envelope) causing partial shorts to appear whenever in operation.

Perhaps you are correct in questioning its reliability?

The preferred valves to follow it were the 6M5, then when TV appeared, the 6GV8 became popular.
The 6GV8 was meant to be used as a general purpose valve.
Mostly used as a vertical/oscillator/output amplifier, It became almost universally the audio amplifier/ output valve of choice. Later, the 6GW8 was designed as a, "purpose made valve" for audio stages.

I hope this is of help.

Wayne Penrith

The 6BV7 was developed and made here by AWV. They were rebranded and sold here & world wide by various valve outfits. AWV advertising material hails it as a innovative Australian design, yet in actual fact it is a direct rip-off of a European EBL1, EBL21, etc. And I agree with Scraps that it is a very unreliable valve. I think the AWV engineers had tried to stuff too much valve in a too small packet - a bit like the 6AQ5. 6BV7's were never made in a 9 pin "Innoval" package as only Philips ever made "Innoval" valves and Philips never made the 6BV7. Philips did sell rebranded AWV 6BV7's as Miniwatts though.