300B ili 400B ?!?!?!

[deki64]

Jedna zanimljiva prica o EI cijevima.

Imao sam srecu da dodjem do kutije od 50 komada cudnih cijevi koje je EI pravio po narudzbi Americkanaca
kao indirektno grejani klon 300B cijevi,nazalost ot toga nista nije ispalo osim par stotina koje su zavrsile
u Americi i poneka kod mene ,ja sam ih poslao u Holandsku firmu Pink Faun gde su napravili prototip pojacala.
Inace karakteristike su jako slicne 300B i hteli su je zvati 400B,evo sta su Amerikanci hteli:
> I tried to interest the engineer at Ei to build
> > an indirectly heated triode about like the
> > 300B, but packaged like the KT90, as a drop
> > in replacement for existing amps say with
> > EL34, and the guy said he was working on
> > what they said was a 400B prototype,
> > but nothing has come of any of this afaik.
I jos par rijeci:
It was planned to make a plug and play 300B for KT88/6550 (not EL34!!!) Applications.

The heater was made with ! 6,3V/1,6A, Pa=45Watts – the result was planned as indirect heated (because making less problems).

first samples had direct heating.
I think it was discontinued because there came no order with acceptable quantities for winning zone for Ei.

Mozda vas interesuju slike,evo kako su izgledale,u velicini KT90 triodni sistem sa velikim krilima za hladjenje.
Pored slika tu su i krive koje su Holandjani napravili na uzorcima koje sam im poslao i uporedna tabela karakteristika sa 300B

[deki64]

Inace prvi prototip sa tim cijevima kod firme u Nizozemskoj su opisani ovako:

Yes! i have built a single ended with them (together with my colleague/friend Miquel who also works here).
We ran into the tubes needing very large swing (380V p-p) for about 6W output.....

Because that would make the amp quite complex (or an expensive IT was needed) we decided to just use an EC86 and then go into the 400B (!)
this gives approx 3,5 watts, but i do not think anyone will hear the difference between 3,5 and 6W.

The amp has separate supplies for power stage and pre-stage, no feedback ofcourse....
i am using normal resistors for anode load of the EC86, but i found very nice russian military carbon composite resistors of 10W(!)
They are quite big.....10cm,x2cm for a 10W resistor(!)
these sound very very good!

I will send you some pictures in a few days!
(it is still on a wooden board, we finished the pcb for the power supply but we have to buy quite some stuff, so have to save a little money....)

[davorin]

Jesu li dobavljive i po kakvoj cijeni, ako jesu?

[deki64]

Vise ih nemam osim par za kolekciju,oko 40 sam prodao u Nizozemsku po 10 eura komad pre par godina.
Cuo sam da ih ima jos nekoliko jedan iz BG i da je trazio 25 eura ali nisam ga kontaktirao,samo sam cuo od drugih.

[deleted user]

Ne bi me cudilo da je u pitanju g, Nikolic...

[deki64]

Haha kako se na hrvatskom kaze vidovit?

[deleted user]

Haha kako se na hrvatskom kaze vidovit?

Isto tako, iako za doci do zakljucka o kome je rijec ne treba se zvati Milan!