This radio is one of the most highly regarded vacuum tube-based receivers made by Collins. It features a double conversion superheterodyne circuit that is supplied by 22 tubes and it weighs a mere 35 pounds (its predecessor, the 75A-3, weighed 50 pounds). The original cost in the 1950’s ranged from $495-$695, a considerable sum at the time!
Our receiver is designated as a 75A-4A. Collins made the model 75A-4, not the 4A. The 4A is a regular Collins 75A-4 that has been modified by one of several private individuals. This unit was most likely given a professional modification by W2VCZ, Robert Stankus. The new nameplate is evidence of this.
This Collins will receive AM, CW, SSB (Single Sideband), and RTTY. At the time the receiver was made SSB was the new mode that everyone wanted to use. The 75A-4 was designed with SSB in mind and it is noted for its excellent SSB reception. To complement this receiver we also have a Collins 270G-3 permanent magnet (PM) speaker with brown flocked grill cloth. This unit works well; but, it is slated for an overhaul in the future. It makes up part of the 1950s section of our amateur radio station, N1EPJ, which is housed in the Massie Wireless Station.
References & Additional Resources:
Universal Radio specifications page dedicated to the 75A-4 Collins.
https://www.universal-radio.com/catalog/commrxvr/75a4.html
Recommended capacitor replacements for 75A-4A.
http://www.collinsradio.org/collins-75a-4-receiver-7-deadly-caps-ripple/
Comprehensive specifications information presented by Collins Collectors Association.
https://www.collinsradio.org/cca-collins-historical-archives/the-equipment-of-collins-radio/the-black-boxes/75a-4/
Shortwave Receivers Past & Present, 2nd Edition, by Fred Osterman, p. 52