The AM Forum

Just found a bunch of new RS1003 tubes. Seem nice candidates for a few experiments, so I ordered sockets. Anyone ever used this tube?

Here is a data sheet....auf Deutch!

They are good up to 100 MHz, and the tube audio people like them.  Apparently, good performance as a triode connect SE audio amp.

http://www.r-type.org/pdfs/rs1003.pdf

Interesting tube. Here's another datasheet... in English.

http://www.mif.pg.gda.pl/homepages/frank/short/054/4/436.pdf

Not too many tubes that I know of at this power level that use such a low plate voltage. Reminds me of a 4D32, in that way.

I was a little concerned about input/output shielding on this single-ended tube. Then I saw this socket.

The feedback should be low, the pin-out is quite clever. The grid and the two anode pins are shielded by two G2 pins, the filament pins and two cathode pins and are at the opposite side of the base. For HF it does not worry me. . I suppose that the shielded base will be fine for 50MHz up

From what I've read, these tubes were commonly used for low power VHF FM broadcast stations in Europe. That's probably where the shielded socket was used. It looks like they went to considerable effort to make such a socket. I assume it was necessary to do so.

Using it at HF would require a physically larger tank circuit and with the single-ended tube design it can complicate the layout of components. I'd still keep good I/O isolation in mind. But, maybe I worry too much. ;)

For sure I will keep it in mind. When I have the parts together and a chassis, I will make a 2 stage cathode modulated transmitter, A driver tube driven from a Chinese DDS vfo that I also use for my Philips transmitter and two RS1003 tubes in parallel, PI filter output.  The PI filter above the chassis, all driver electronics below.  I will make the transmitter for 40 meters.
I will keep you informed and will measure I/O isolation.

Cathode modulation is something I haven't studied much. It should be interesting to follow along. :)