A previous owner had installed a Collins mechanical filter in the 1st detector stage (normally a coil with crystal phasing). The Collins filter is part number 526-9395-00 and labelled 'F 455 Z 7' From google searches, it appears that this might be an SSB filter, but I. But, the Collins does improve the "sound" of the received and transmitted signals. And, under good signal conditions it's a matter of your personal taste. I hear the difference when I switch back and forth between the two filters, and I'm a died-in-the-wool fan of Collins Mechanical filters so it's worth it to me. MECHANICAL FILTER COLLINS COLLIN sas 9364 00. MECHANICAL 82 I o z E 00 0 o E o o o. O 2 0 08 O 8 o o o N011VnN3LIV N011VnN311V NOILVnNILIV NOILVnN311V 2 o z o O o 0 0 0 E. N011VnN21LV oz jih u- ga - NOILVnN3LLV N0i1vnN3LLv NOILVnN3LLV Jin NouvnN31Lv aa.

Collins Mechanical Filters For Sale By Owner

The Collins Radio Company was founded by Arthur Collins in Cedar Rapids in 1932. The company started business constructing transmitters and amateur radio equipment and got much experience producing aeronautical transceivers and transmitters during wartime. This experience was used in the production of amateur radio receivers (the famous 75-A series) after the war.
After 1949, Collins brought out communication receivers covering not only the ham bands but the complete shortwave spectrum. These sets startiung with the 51J / 51-J with linear analog dials covering the shortwave spectrum in 30 1-MHz-segments were very successful. The Collins 51J-3 (and it's military variant Collins R-388/URR) was equipped with coil filters, the Collins 51J-4 (military variant R-388A) was the first Collins set using their very famous mechanical filters, it appeared on the market in 1957.
It's military successor was the 1951 model Collins R-390/URR with it's mechanical digital frequency display (frequency readout on a kind of odometer), and the later Collins R-390A/URR, which gives nearly unsurpassed AM reception on the tropical bands with. You find the Collins mechanical filters 16/8/4/2/1/0,1 kHz only in this popular variant - it has been produced by a series of other companies under contract.
For civilian use, Collins had a range of smaller lightweight amateur band receivers, the legendary Collins 51S-1 covering the complete shortwave spectrum from 200 kHz - 30 MHz in 1 MHz segments offered a linear analog dial with a dial resolution of better than 500 Hz and was fully equipped with tubes.
Collins was taken over by Rockwell Intl. in 1974 and is since then still very active in the military and aeronautical communications segment.

Collins Mechanical