Fuling said:
And your point is?
most valves are indirectly heated nowadays
a "dirctly heated rectifier" is one that uses the fillaments as
the cathode , not one that has a cathode conected to a fiilament,
this is called indirect because there is a fillament and a cathode
and not a filament used as a cathode
hope this clears things up for you.
The point is that a GZ34 inevitably connects its heater to the HT supply, or, to put it another way, if you don't realise that's going to happen, you can end up short-circuiting the HT supply. the fact that Mullard call it an indirectly heated valve is something of a misnomer because it has to be treated as if it was directly heated.
Slow start DH rectifier with slow start ?
GZ34 do it naturally but you could make a directly heated DH rectifier such as the 5U4G present a slow start if you like . I have achieved considerably better than the 2 seconds it usually takes to warm up a 5U4G by using series resistors and a 16V supply . Filament resistance cold is low so it works similarly to how a CR filter works , trouble is adjusting to provide the exact 5V required . Current sinks with DC can also achieve this easily but possibly a little over the top for rectifiers . Saying that I did use current sourced LM317 filaments for a PL504 amp I built a few years ago , waiting for it to warm up was rather boring
Very inefficient but the series resistor scheme works superbly with PY500A . Slow start with an even slower start
316a
Jax said:We could call GZ34 a direct heated rectifier with slow start and be done with it
GZ34 do it naturally but you could make a directly heated DH rectifier such as the 5U4G present a slow start if you like . I have achieved considerably better than the 2 seconds it usually takes to warm up a 5U4G by using series resistors and a 16V supply . Filament resistance cold is low so it works similarly to how a CR filter works , trouble is adjusting to provide the exact 5V required . Current sinks with DC can also achieve this easily but possibly a little over the top for rectifiers . Saying that I did use current sourced LM317 filaments for a PL504 amp I built a few years ago , waiting for it to warm up was rather boring
Very inefficient but the series resistor scheme works superbly with PY500A . Slow start with an even slower start 316a
EC8010 said:
All Gz34 maunfacturers not just mullard list this valve as "indirecly
heated because it is.
reason: A fillament is used to heat the cathode ,the fact that is shares a common connection with one side of the cathode
in no way makes it directly heated the ht current still flows through the heated cathode and NOT the fillament as in a "directly heated valve" now if all you guys can do is argue about
fact then i wont be on this forum long.
Jax said:We could call GZ34 a direct heated rectifier with slow start and be done with it
"we"(i take it you mean the people on this forum) do "we" have
the right to change facts.
Well since 1950s or so
I do agree with you though, the GZ34 has a heater that is separate from the cathode. Therefore the cathode is indirectly heated. The fact that it is wired to the filament in the base is of no consequence in the naming. It is handy that you can just plug the thing in to any amp...
Just scored myself a free mullard metal base GZ34 the other day, great valve!
Jax said:Stormy,
Most people here know that the GZ34 is indirectly heated. The humour in my line obviously flew right over your head.
You seem to be new on the forums, please chill down a bit, lean back with a good pint and learn to know the people here
Cheers
Sorry I have been wound up a bit on forums recently I must apolagise for being ratty
ShiFtY said:
Well since 1950s or so
I do agree with you though, the GZ34 has a heater that is separate from the cathode. Therefore the cathode is indirectly heated. The fact that it is wired to the filament in the base is of no consequence in the naming. It is handy that you can just plug the thing in to any amp...
Just scored myself a free mullard metal base GZ34 the other day, great valve!
oops I nearly gave away my age away there then
I was bidding on 2 mullard GZ34 on ebay but thay went to a
silly price as usual.
I use the GZ34 in my 2 1960 ac30's
Stormy
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