You are so kind. Thank you very much.
My tubes look exactly like 4B/551B(D). I will measure the dimensions to be
sure as soon as I can.
It looks convenient that the filament voltage is the usual 6.3 volts.
Interesting is that they count with anode voltage as much as 10 or even 14
Thanks again for your effort.
73, Petr, OK1FIG
From: Marco IK1ODO -2
Sent: Tuesday, July 08, 2014 2:50 PM
To: [email protected]
Subject: Re: Fw: LF: Pure off-topic: old tubes
15 years ago I was used to buy truckloads of test and communication
equipment from Johns Radio in Bradford (now he is in Batley).
He had a lot of equipment from the closure of STC R&D labs. I
acquired many valve handbooks: AEI, GEC, STC, RCA, about 20 books.
I dug and found some data on a similar tetrode, possibly a newer
version of 4B/55. I have 4B/550E, 4B/551B, 4B/551BD. It is in Volume
2B, Components, of S.T.C.
Please find the scan in www.spinelectronics.eu/ftp/STC_tetrodes.pdf
Petr, do they look similar?
73 - Marco IK1ODO