The company IPRS ('Întreprinderea de piese radio și semiconductori' which translates as 'enterprise radio parts and semiconductors') located in Băneasa borough of Bucharest in Romania, founded in 1962, produced electronic components and electrical and electronic equipment including germanium transistors. These sometimes bear their logo of a Greek 'beta' symbol, but are often unbranded.
I am grateful to a correspondent, Raul Neagu, who has sent me information from a Romanian electronics book: 'Agenda radioelectronistului' by Nicolae George Drăgulănescu. This provides data for the following IPRS germanium transistor types:
- PNP types AC180, AC180K, AC184, AC188, AC188K
- PNP types EFT38S, EFT301, EFT302, EFT303, EFT311, EFT312, EFT313, EFT321, EFT322, EFT323, EFT341, EFT342, EFT343, EFT367
- NPN types AC181, AC181K, AC183, AC185, AC187, AC187K
- NPN types EFT373, EFT377
The AC types use TO-1A cans; those with the suffix K have the same block heatsink that is found on Telefunken types. The EFT types, also in TO-1A cans, appear to be a second-source equivalent to devices in the SFT series originated by the French company CSF. The early semiconductor industry in France is obscure in its own right, so how a Romanian company established such a commercial arrangement is unclear to me.
I also possess an earlier Romanian data book: 'Catalog de Dispozitive Semiconductoare' by Veronica Vătăşescu and Şerban Epure, 1966, which you can download from the Web. It lists the following EFT types as equivalent to SFT series with the same numbers:
- low-power PNP types EFT124, EFT125, EFT130, EFT131
- low-power PNP types EFT306, EFT307, EFT308, EFT317, EFT319, EFT320, EFT321, EFT322, EFT323, EFT351, EFT352, EFT353
- high-power PNP types EFT212, EFT213, EFT214, EFT238, EFT239, EFT240, EFT250
Here is an AC180K. It uses the TO-1A can inside a metal block heatsink. It is a germanium PNP medium-power audio-frequency amplifier. You can see the printed 'beta' β of IPRS.
I believe this transistor type EFT83B was made by IPRS although it does not have a 'beta' on it. It is a PNP germanium alloy transistor but am unsure whether it is for AF, IF or even RF applications. It is commonly available on eBay, but it does not seem to have an SFT original and I can find no technical data for it.
If you can clarify this, please
Here are three transistors: types EFT321, EFT322 and EFT352. Unlike my EFT83B transistors, these are painted black. I bought them from someone who said that they were made by CSF, however I no longer think that likely. They are all germanium PNP alloy-junction low-power types.
Here is an EFT213 power transistor. Radiomuseum describes it as a PNP germanium alloy transistor intended as AF power amplifier. Rather oddly, they describe the original SFT213 as intended as power switch.
If you can have original data sheets for either, please
I have nothing more to show in the way of Romanian semiconductors. Please help fill this gap if you can!