Recent content by adolph

OK, sorry to ask so many questions but my confusion arises from your original description "beam Pentode", you did not say if it had beam plates or a suppressor grid so I was not sure if it was a beam Tetrode or a Pentode. Your last post tells me it's a beam Tetrode but not a classic beam Tetrode...

OK so let me get this straight:- A beam valve is not the same thing as a Tetrode and does not exhibit it's characteristic "kink" despite having the same number of elements? And the ECL82 you dissected was a beam valve and exhibited the same characteristic as a Pentode? RGDS Adolph

Whoop's typo, Pentode should have read Tetrode, however it do not change the fact that Tetrodes were not popular. But going down to your main point of strange arrangement, what other Tetrodes are you comparing it with? And what was the diff. I am first to admit little knowledge of Tetrodes as in...

Sorry to come in late, have just read the thread (bin away). r.e. Picture size. Here is a site that has a great app called pics resizer, works well easy to use and free. However only sizes down, for up you need PhotoShop. http://bluefive.pair.com/pixresizer.htm Hope this is a help, really want...

A second reason for the odd winding is that the Pentode valve characteristic, at certain points a rise in the anode voltage will cause a fall in the anode current, this is caused by secondary emission. When electrons strike a surface at high velocity they tend to knock other electrons off these...

The screen grid in the Tetrode valve was to reduce the large electrostatic capacitance between grid and anode of the Triode valve which tended to limit it's high frequency performance, if held at a fixed potential the the screen grid acts as an electrostatic screen and isolates the input circuit...

Burosch electronic Stuttgart make an audio test CD with 96 tracks on it. Track 73 & 74 are 3k & 3.15k at 0dB. Described as "Reference frequency to test the speed and  flutter of tape recorder" Google it there might be a local rep.

Very interesting, but I don't think I have seen a commercial device that uses this as a safeguard and one thing for sure you can't "rejuvenate" a striped cathode. Maybe they want you to wear them out?

For sure, in my later 5/10s I used an ECF82 with the triode as a "concertina" worked well and made it more commercial as it saved both space and cost. The downside being that you can't use it in the 10/20 as it wont drive EL34s. I will also be interested to see if 12W comes out of the kit, with...

During the manufacture process the barium coated cathode has to be activated by heating to convert the coating to oxide form. This gives off a lot of gas, the getter is a small pan made of barium or sometimes magnesium which is fired by induction heating and then remains highly reactive and...

I have read with interest all of this thread and would like to offer a few answers. The Getter has one powder charge it fires once and is then disconnected. The correct way of limiting current in a valve heater to use a Varistor or VDR. Cathode Ray Tubes do suffer from cathode poisoning, I...

I worked my way through college building Mullard 5/10s, I think the best design they did, if you bought the best transformers it really sounded  great. By the way the Mullard designated name for the phase splitter was "Concertina". Regards Bob

Here are TS parameters for Infinity Dynamic 8i yellow woven kevlar driver. Be warned though, I have designed many speakers and can't remember getting one right first time. Regards Bob