IDEAS PAGE .
This receiver was designed to replace the old 1030 mhz receivers.We tried to find an easy
,simple and relatively cheap solution.The receiver ir built to feed the 11ghz and 4ghz
rf heads via the coxial cable.
It is made of :
* preamplifier made of two mar6 Minicircuits mmics. It gives 15 db gain and about 3 db nf.
It is a simple strip line circuit,using smd condensators. It provides 14v to the rf heads with
a switch .The receiver can be used directly in 1420 mhz with a low noise preaplifier.
*a 1420 mhz converter from a tv (1255 mhz ) converter described in a RADIO-REF book in 1982 (old !!!) from
f1cwd and f1fuu . It is easy to build, simple . It uses only easy to find components .
We seriously modifed it for our use :changed the plastic variable condensers to Johanson , replaced
the 75mhz xtal with a 90.833 mhz,the if is set to 33 mhz (10 mhz bw) . We did not use the if
preamplifier ,there is enough gain in the if strip.
* the if strip uses three sl560 ic ,it gives 90db gain .
* the detection is the one published on our page from Mr Montignac.
The op27 amplifier is used with a gain of 1, no integration.
* the signal conditionning system is classical . It uses three op07 , the first for offsetting
(substract a precise dc voltage tothe receiver noise ), the second for gain (1/10 ,1, 10,100 ),
the third for integration (1 sec ,10 sec ) . All that is followed by the chart recorder.
We added a small audio amplifier with a lm386.
The receiver is constructed in modules built in tin boxes.There is a standart regulated power supply
(7812 and 7912 well decoupled ), a blower for the regulators . All that is in a standart 19 ' rack.
The receiver has a -90dbm sensitivity , and is very stable .