This is the Realistic (Radio Shack) TRC-458, 40 channel SSB/AM base station. This was Radio Shack's next model down from their TRC-457 deluxe base station, and was offered from 1977 to about 1980 when it was replaced by an almost identical looking, but much less capable, TRC-490. The TRC-458 sported such standard features as Volume, Squelch, R.F. Gain, and a receive-only Clarifier. Separate switches selected noise limiting and noise blanker circuits as well as the P.A. function. The S/R.F. meter was large and easy to read. Like the Cobra 139 XLR, the TRC 458 (and 457) used the Uniden UPD 858 PLL chassis, which made this radio a very interesting platform for experimenting with different types of modifications. PLL mods could net over 200 channels, centered anywhere between 26.085 and 29.800+. The transmit strip could be wide banded by simple cuts and jumps, and a realignment. It was also fairly easy to unlock and expand the clarifier range to +/- 5 Khz. Transmit audio gain could be increased by changing the feedback resistor on the mic preamp I.C.. Audio bandpass filters could be changed to suit individual frequency response needs. It was also easy to implement controlled carrier schemes, thanks to the method of modulation and power regulation. Replacing the final transistor with a beefier one (Such as an MRF 477) would net over 25 watts of output power on SSB.
General operation yielded decent receiver performance, with decent adjacent channel rejection. The noise blanker operation was fair, but not as good as later chassis designs.
I picked up my '458 in the 1981 time frame as a dead unit for $15. The PC board was cracked, and after fabricating a few solder bridges and applying some epoxy, the radio was on the air. This radio served as my primary radio (I finally retired my Midland 13-885) for a number of years. My father-in-law also used it on the tech portion of 10 meters for a while as well. I finally sold the radio in the late 90's, to a ham who still uses it occasionally on 10 meters. On a scale of 1 to 10, I would rate this radio at about a 7 1/2, based on all of the capability that it had.
The sad part is that many of the parts for this chassis have been discontinued and are very hard to find. So if you have one that is in need of an audio power amp or a VCO I.C., good luck, unless you can fabricate a substitute. All the more reason to find a dead parts radio to keep the good unit alive.
A few people in our area ran TRC-458's, including Uncle Chucky, Midnight Cruiser, myself, and others.