Loewe Radio Kleinprufgerat Type 4121/2 Signal Generator Help

[bobskie]

Hi everyone this is my first post here. I just purchased this old signal generator. I have recently gained an interest in vintage radio restoration and read somewhere that these were used so since it was in my area I bought it. I then realised I really have no clue as to what is actually is/what it does. The text being in German is no help. I can't even work out what type of generator it is, audio?, RF?
If someone could help me understand how to use this and for what i would appreciate it Thanks everyone!

[karesz*]

Hello!

You have an interesting apparate; I would say its an oldy from 50`s or so, but the label says us, produced in 1982!?...

For me is a litle unclear the role of the socket group of 1--3; my speclation is:

I think these Generator has an internal Audio Oscillator too (N.F. Spannug) and there signal-output is on sockets 2,3, with it is a continuity test on sockets 1,2 makeable, than "Prüflampe" indicate us a good situation...

God luck with them, Karl
Ps,
I found it just yet by Radiomusem, it has an 50Hz internal modulations signal, and same will used for continuity checks too. Production year should be 1947! ...

[AC/HL]

Translated from the original German:

Simple test transmitter with seven fixed frequencies and a variable range from 430 to 490 kHz, with modulation (50 Hz), adjustable RF output voltage, additional AF output as signal follower, line tester via built-in signal lamp. Fixed frequencies: 134 kHz, 168 kHz, 213 kHz, 299 kHz, 606 kHz, 927 kHz, 1200 kHz.

[bobskie]

Originally Posted by karesz*

You have an interesting apparate; I would say its an oldy from 50`s or so, but the label says us, produced in 1982!?...

Thank you for your help and those links, I had a good search but couldn't find anything! Where are you seeing the label saying 1982? Also do you have any idea how to use it?
Thanks.

Originally Posted by AC/HL

Translated from the original German:

Hi may I ask where you found this information? Seems like I got a fairly good item if it works then. I really have no idea how these work, how would I go about transmitting a frequency?(what would need to plug in etc). Thanks for for your help.

[AC/HL]

The text was on the radiomuseum page Karl quoted, passed through Google translate.
It appears to be a spot frequency signal generator (not a transmitter as such) with an additional variable IF facility, designed for checking Medium Wave radios. It looks quite useful, but just for that one purpose. You shouldn't need to use a signal generator for most basic fault finding, something for future use perhaps?

[bobskie]

So does a spot frequency signal generator generate a solid tone that can be picked up by a radio? Also what is a variable IF facility. Would i need to plug in an antenna in order to use it? Sorry for the probably obvious questions but i really am almost entirely new to the world of radio equipment. Thanks.

[bobskie]

Well I just plugged it in and gave it a try, seems to work well generating fairly accurate tones on each frequency though I couldn't test them all as my radio does not go so low. The H.F Spannung dial appears to be some sort of fine tuning and slightly alters the frequency. The other dial when option 8 is selected allows selection of different frequencies in the range, though I couldn't test this because my radio doesn't have this option. Now all I need to know is what the different sockets are for, I'm assuming one is for an antenna but what about the rest? Also I'm still not sure what the pruflampe is for. Thanks

[paulsherwin]

It means test lamp or indicator lamp. I suspect it's just an on/off indicator. It it doesn't light up then the bulb may be blown.

[karesz*]

Hello Bobskie,
I translated the texts first and guees the functions, than sorry, only after that I wrote simple "Loewe Radio Kleinprufgerat Type 4121" in google...
You can see two times 1982;
1; on label "Eichtabelle", after "Werknummer 4121"=> 05.14.1982
2; on label "Löve Radio Opta" (above "Kleinprüfgerät") => Nr: 412105 _1482
For using it check please the link on my pdf attachment_in German, but has much pictures.

@ AC/HL, "...designed for checking Medium Wave radios."
Sorry, dont agree, than their 4 fix frequencies between 134-299KHz are designed for LW(Long Wave) band radio tests, in further it has 50Hz internal "signal" for injection as signal follower and continuity testings too!
Best regards, Karl

[bobskie]

Ok so would I just plug in a cable into the numbers 1 and 2 pins and then touch them together would the bulb light? Also if i plug into 2 and 3 and attach to a speaker would I hear an audio signal? If I am understanding this correctly what sort of voltage would be coming out of these plugs.

Best regards.

[karesz*]

yes, its so to make, you have here 50 Hz as "signal", but what kind of amplitude/current; I dont know yet_ be carful with a small loudspeaker as load...
Karl

[AC/HL]

Originally Posted by karesz*

@ AC/HL, "...designed for checking Medium Wave radios."
Sorry, dont agree, than their 4 fix frequencies between 134-299KHz are designed for LW(Long Wave) band radio tests

Quite right, I meant to say AM, but they clearly are LW not MW. Could it be designed for testing those radio via telephone wire receivers that have been mentioned here before?

[bobskie]

Originally Posted by karesz*

yes, its so to make, you have here 50 Hz as "signal", but what kind of amplitude/current; I dont know yet_ be carful with a small loudspeaker as load...

I will need to give that a try.

[bobskie]

Originally Posted by AC/HL

Could it be designed for testing those radio via telephone wire receivers that have been mentioned here before?

Could you explain what these radio via telephone line things are? I had a search but can't find anything.

[AC/HL]

Here: https://www.vintage-radio.net/forum/...ad.php?t=25712

[Chaparal]

This Loewe Kleinpruefgeraet 4121 is not from 1982.
It is build in 1947/48 version 5 (4121.05)
1482 is the serial number

The specs are:

For Aligment
3 fixed frequencies (LW) apprx. 160, 200, 300 kHz
3 fixed frequencies (MW) apprx. 600, 900, 1200 kHz

For IF-Alignment
1 fixed frequency apprx. 130 kHz
1 var. frequency apprx. 430 ...490 kHz

RF Signal output voltage: var, max. 1V
AF-Signal output voltage: apprx. 3.5-4.5V ~50Hz
Testsignal for cable testing etc. (Pin 2+3)

Modulation freq.: 50 Hz

Leitungspruefung (Pin 1+2) short or continuty Tester

[bobskie]

Thanks for the information, I don't quite understand what the difference between the test signal and the continuity tester is though?

[Chaparal]

The continuity Tester is only a
6.3V AC Voltage and a lamp
Pin 1+2 short - lamp on
Pin 1+2 open - lamp off
used for testing cable, coils, trafos etc.
The lightning of the bulb depends of the resistance from DUT.
The lamp is also used as a power on control indicator (short 1+2)

The AF output (50 Hz) Pin 2+3 can be used for signal injection
(Audio Amp, phono input) or AC cable testing (with headphone on the other end)

some more specs of 4121:
-----------------------------
Tube: EF 12 or 6J7 (russ)
Mains: 110 / 220 V~, approx. 6 VA

RF out high (PIN 4+6) max 1V
RF out low (PIN 4+5) with devider 1:10

Poti 'HF-Ausgangsspannung" (RF-Outputvoltage) in left position will stop oscillation.
Freq. Accuracy ±10%

For shortwave testing/alignments the harmonics of the 1200 kHz signal are used.
(6, 7.2, 8.4 MHz etc.)
Note: watch for mirror frequencies

------
Peter