SRA PR81 (RA 135) Swedish Military Radio
Ойын-сауық
This is a Swedish military radio, the export version of the SRA (Svenska Radioaktiebolaget) RA 135.
It is a very light radio, likely to be used by infantry troops on the field.
It operates from 42 to 43MHz and has 6 channels. The power output is about 0.7W FM
Power range is from 12 to 15V.
There are two volume levels for the squelch. The original handset had the volume control on it.
This radio came with no battery. I made one using 4 LiFeP04 cells and a S4 BMS. It ended up with 1300mAh, not bad.
The connector is similar to the one used by Racal radios, and the pinout for audio, mic and PPT is the same. I didn’t tried to power it from this connector.
Each channel has its own quartz, and the final frequency is given taking the 12Mhz from the FI out.
The antenna that came with it, is not a perfect match, it is tuned to 60Mhz, and with a counterpoise it goes down to 1.10 SWR on that frequency.
If you know what this BNC could be for please let me know on the comments. Maybe a signal injection to use it in other frequencies…
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Пікірлер: 27
Thanks for sharing the details of this little radio.
Exelente equipo! saludos de SA7CAU
Meilleur vœux 2024, very interesting this little transceiver 👍👍
Same compact radio design as in many other ones: use the modules to go into the vertical dimension. Otherwise, it would not be possible to fit so many discrete components. Shielding of the modules is another bonus specifically useful for radios.
Thanks for the video! Interesting device.👍🏻
@Radiogenes
7 ай бұрын
Yes! Not many information. That is why I wanted to make a video for preservation. Thank you for dropping by
saludos desde vk2! I enjoy your videos very much !
@Radiogenes
7 ай бұрын
Thanks!! Happy 2024!!
@aschlack8889
7 ай бұрын
Ya tengo el ru-20 gracias nuevamente por la inspiracion feliz 2024 !
@Radiogenes
7 ай бұрын
@@aschlack8889oh ! Otro RU-20 en el aire!! Felicidades
Very nice
@Radiogenes
7 ай бұрын
Thank you!
Interesting radio! I am surprised you did not print out a frame for the battery with contacts on the top. I like the flat pack design, easy to mount in a chest pouch.
@Radiogenes
7 ай бұрын
There was no room! Just the batteries and the bms… have a nice 2024!!
@Subgunman
Ай бұрын
Thanks! Is there anyone in Europe that can "cut"crystals to frequency in todays world?
When it transmits, does it use the same crystals to generate the carrier frequency as when receiving? I guess that would be possible if they mix, say 54 MHz crystal oscillator with 12MHz IF frequency oscillator to get 42MHz transmission frequency.
@Radiogenes
7 ай бұрын
That is a exactly what it does. Christals are on that 54MHz
Interesting, try checking if there is low frequency on this BNC - maybe it's for amplifier. In my life i seen military amplifier that demodulate FM and modulate it again with higher power (just as example of interesting design) - maybe that BNC is used for carrying signal without RF - for some external PA in vehicle. Did You 3D print in olive green!?
@Radiogenes
7 ай бұрын
Cool idea!! I will see! Yeah olive print!! Tricky one, it needs 240 degrees
@greenpedal370
7 ай бұрын
I agree, it's for an external PA
@Radiogenes
7 ай бұрын
@@greenpedal370 I have seen on other pictures on Internet that there is a cover with a written HÖRTEL
@greenpedal370
7 ай бұрын
@@Radiogenes Doesn't help. I translated that to "hearing"
@herrkulor3771
7 ай бұрын
@@RadiogenesIt is "Hörtelefon" . It can be used with monofon and hörtelefon. In the hörtelefon mode, the loudspeaker is turned off. Hörtelefon = earpiece in the english instructions. It looks like an in ear Headphone. It costs 20 SEK, about 2€