[Milsurplus] SCR-522 Alternate Uses

[B. Smith]

The SCR-522 has a rich history of alternate uses and modifications. You 
can even use  the set on on your local FM repeater. Connect a varicap 
from crystal socket to ground then inject audio via a external amplifier 
through an  RF choke to the crystal side of the diode. We used a small 
value varicap or you can even try a power supply diode.   On CR-18/AR 
crystala 1 to 2 Kcs  swing at the  fundamental freq  can be obtained but 
you want a smaller value of deviation near  250 cycles due  to the X18 
multiplication.
On the Receiver use slope detect.

The 522 was occasionally pressed into repeater service during the early 
days of 2 Meter FM as Motorola 80D's etc. could be expensive. Usually 
the frequency was 146.94 - Most large towns started off with a  .94 
repeater and you only needrd one set of crystals when mobile.  :-)   
There were also  experimental AM repeaters  which were interesting as 
the carrier stayed on continuously.

Due to the multiplication factor on receive you can use same receive 
crystal for  7 different receiver frequencies. For instance you can use 
a crystal and multiply by X12 to cover 108-116 and then use the same 
crystal in a different multiplier scheme such as X14 for 124-132 Mcs or 
X16 for the 2 meter band.   My favorite demo frequency was to channel up 
for the   ATIS at the nearby airport but you can also cruise the lower 
VHF frequencies for aircraft comm.

Remember that the receiver can go down  into the edge of the FM Radio 
band which has a top edge of 108 Mc and you can slope detect those stations.

k4che