Newly Acquired Telefunken Concertino 5384W - Questions

[firedome]

Early stereo before mpx

used both the AM and FM bands to carry signal for L + R channels, so maybe that's why 2 x EM84, but not sure how SABAs were configured. We had a few of the German jobs over the years but they often use odd tubes and are difficult to work on because hard to get parts for, plus tended to be very low power. Many used oval speakers similar to car radios. The muting issue sounds like it could be the switch itself, try a shot of DeOxit 5.

BTW I never saw a German radio of that era that DIDN'T have a SW band!

 

[philr]

Roger, I also thought about stereo on two bands as a possible reason for two EM 84 tubes but the only radios I have seen with that were Japanese models. My Saba has a Multiplex adapter and two magic eyes.  

 

And I might be wrong but I thought the stereo was on both AM bands. Also, the reason why they went with multiplex stereo separation here in North America is because the US was concerned about not making the mono radios obsolete as they would get just a part of the diffusion if it was to be sent on two different channels. 

 

[tolivac]

Yes,in the days before Multiplex-stations had the option of using their AM to carry one channel,and the other channel on the FM-this had two big problems-the audio quality was mismatched,and radio station managers and owners didn't want to tie up their AM to carry essentually the same program as their FM.So called "AM stero" didn't last long-becuase of quality and the expense of the stereo encoder for the AM transmitter.And many older AM transmitters wouldn't work with these devices.So both the radios and encoders became collectors items-sometimes stations would give away their AM encoders to whoever wanted it!And the 4 diffrent formats for aM stereo made for another issue-radios had to be able to decode each of these formats.A selector switch was on the radio so the listener could select for the format the station was using.In one station I put in a transmitter for-new Continental Electronics 317-used a stereo encoder on loan from Continental-did work OK.But used it for only 2 weeks-the time of the loan of the encoder-returned it back to Continental.The station didn't want to go stereo.
At the workplace here-the transmitter site we also have a B&K 747-its cheap plastic case has fallen apart-you have to look around for its settings book-the sturdy wood cases of the Hickoks have stood up better-and the Hickock is better quality and more accurate.I reach for the Hickock whenever I have to match up 5879 or 6AK5 tubes for the GE transmitter low level modulator audio stages.You have to match tubes in these stages or the audio is distorted from the transmitter.I have had to do this with many other AM transmitter low level modulator audio stages.

 

[tolivac]

PhilR-looks like PE66 TT was commonly used-like how the tT accesries can be securely stored in the TT compartment-the clips that hold the 45 adaptor.NICE!Suppose the boxes hold spare cartridges and styli?And silly me-SW to overseas areas is like AM to folks in the US.

 

[davetranter]

Sound fades out

I had this problem once. Turned out to be the Cathode resistor in the audio power amplifier stage going high. They are usually run very hot (due to cost cutting), but perhaps not in a Telefunken???

All best

Dave T

 

[foraloysius]

AM Stereo AFAIK was also done by using two AM radio stations. By using AM for both channels there was less risk of mismatched signals.

AM on European radios was divided in S(hort)W(ave), M(edium)W(ave) and L(ong)W(ave). In Germany they were called Kurzwelle (KW), Mittelwelle (MW) and Langwelle (LW).

FM is also known as Ultrakurzwelle (UKW).

 

[firedome]

early stereo broadcasting

in the US was always AM + FM until the FCC approved the GE/Zenith sub-carrier addition/subtraction system, which was backwards compatible, in 1961. That's why tuners had 2 separate dials with 2 separate indicators rather than a selectable multi-band dial with a single indicator. The world's first stereo all-in-one receiver was the Harman-Kardon Stereo Festival TA-260 of 1958 and many copied the idea.

Most US made FM radios and receivers were manufactured with provision for adding multiplex either on the chassis or outboard during the period 1958-61. There days those add-on multiplex units can rival the tuners and receivers they were intended for in price!