I can answer this. I was still working for RS when this radio came out as the '52. It was a "wedge" radio in RS's product line. I need to explain that. Up to about late 1974, there was a $159 price point for a 23 channel radio that had a S meter,delta tune, ANL/PA switch. There were a scant few 23 channel radios that were no frills without a meter or any features, just the basic FCC requirements of a transmit/modulation indicator light that sold below this price. In '75 with the CB boom building, there were several price buster radios selling through department and auto stores that were breaking this price point around $130 such as Kraco, whatever K-mart's brand was, Spark-O-Matic and many others that were eating the full feature mobiles sold by the main manufactures lunch based on knobs and switches.
Radioshack's love affair with Hitachi was also straining at the time as they made relatively uncompromised designs, so RS started to court Uninden for cheaper radios. The TRC-52 had all the features of the TRC-24x which was the mobile full featured AM set that still sold for $159, but sold for about $30 less. That difference and cheaper build sold like hotcakes compared to the 24C and also looked much more high tech with the larger meter and departed from the old wood grain decor. The TRC-24 was a much better radio and the TRC-30x Navaho base was the same board inside.
In the lead up to the 40 channel expansion, nobody knew at the time until last minute what the bandplan was going to be. Several companies such as RS and Sharp were either saying outright or encouraged to hint that the new radios were going to be able to be upgraded to whatever the new bandplan was going to be. Lots of people were holding off on a purchase waiting for the new radios to come out and 23 channel radio sales dropped off to nothing. I was still working there when the came out with the TRC-57 base station that was pll based, but 23 channels. Nowhere did they say the radio was upgradable to whatever the new band plan was going to be, but we were told to push the hint that due to the radio having advance pll circuitry, it would be upgradable. After I left, the trc-152 came out. First one I seen was bought by another employee I used to work with. The 152 looked exactly the same with 23 channels, but instead was based on a pll synthesizer. They used the same chassis and metalwork, but the board was different. I don't know if upgrading was still part of the sales pitch that never happened and the FCC never permitted it, but the soon followed with another radio that looked just like the trc-52 and 152, but was 40 channels due to the PLL design naturally called the TRC-452 which was the same radio, but a 40 channel rotary switch. They followed this by another one that looked the same, but had a 2 digit LED display that I don't know if it was the same radio inside or not.
These were kind of strange times due to market forces and uncertainty what the FCC was going to do and accounts for some of these hybrid 23 channel radios that either were capable of expansion or immediately offered as a first-in-the-market, legal 40 channel radio with a non-digital rotary switch. The 52/152 was one of many such transition radio models that went from crystal synthesis to PLL in the same chassis.
Hope this answers your question
As a base station a Realistic TRC-52 with a 1/4 wave antenna. I found that the TRC-52 had a very robust sounding audio compared to later 23 channel radios.
A sidebar if I may.....The last listing for a TRC-52 in the Radio Shack catalogues IIRC was 1977. I keep finding references to a TRC-152 on the net that looks identical but cannot find it in the catalogues. Anyone know the history on this unit?