b91 SRA C400 and C502


SRA C502 (4m) on 10m

I didn't manage to convert it to 6m, but modified the receiver to 10m, and the
sensitivity was very good. Problem with those social democratic constructions,
+12V as ground reference, with negative voltage regulators makes service
complicated, but trade unions may celebrate - since you use very much time
for service. It is however, possible to modify this - in a civilized world, use the
receiver separated from the rest of equipment, with +12V supply voltage, and
+9V regulator

SRA C502 receiver conversion to 10m FM, overall circuit, note that operational
voltages refers to ground - not +12V as the socialist democrats prefers, or was it for the English trade union?



Converting SRA C502 to 10m



Fig 98-1 29MHz HF trinn for C502 (Amatørradio April 1993 side 102)





Fig 98-2 Tilkoplinger på C502 (Amatørradio April 1993, side 103)





Fig 106-1: SRA C502 (4m) kort brukt til 10m FM sender (AR Mai 1993, side 136)




Fig 106-2: TX mixer SRA C502 for 10m, til høyre sees tilkoplinger for spoler
(4m) kort brukt til 10m FM sender (AR Mai 1993, side 136)





Fig 107. 29MHz 0.1W 20dB gain forsterker med god selektivitet for bruk sammen med SRA C502 TX modul
(Tekniske refleksjoner, AR Juni 1993 side 172)





Fig 108. 29MHz 10W 20(24)dB gain forsterker for bruk sammen med SRA C502 TX modul
(Tekniske refleksjoner, AR Juni 1993 side 172)



SRA C400 "UHF rig"(FN205) .
it is some modifications in the power supply, and few in the receiver.
The receiver is astonishing good and sensitive - in spite of what it looks
like with those old Philips concentric trimmers
The advantage with this old rig is that it uses commonly
available components, or it is easy to find replacements
.


se forøvrig følgende artikler
SRA-C-400 70cm (base stn FN205) xtal info     LA8AK  AR  92-11-006
SRA C-400 (70cm) Ombygging basisstasjon              AR  89-01-021
SRA C-400 (70cm) LF linje-utgang for pakkeradio      QTC 89-04-171
SRA C-400 (70cm) Ombygging rettelse           LA8AK  AR  89-03-067 
SRA CN-505 70cm (synth.) xtal info            LA2EC  AR  92-11-006
SRA CN-605 70cm (synth) xtal info             LA2EC  AR  92-11-006
SRA CN-605 (UHF) MTD Ombyggnadsbeskr.  SM3OAU/SM3CER QTC 90-12-540



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