05-07-2006, 10:47 PM
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Join Date: Apr 2005
Location: Louisville, KY
448 came from an entirely different vendor (factory). Pretty sure their name was "NDI", for Nihon Dengyo Inc", or something like that. That's the reason you've never seen that oddball PLL chip in any other radio. NDI wasn't the biggest supplier to USA name brands, but RatShack sold this one, made with the "Realistic" label stuck on the front and back. Parts can be hard to track down. Not many junkers out there to rob for parts.
The '458 is a Uniden product, likewise a "private label" source for RatShack way back then. The same main circuit board appeared in a handful of other brands/models from 1978/79. Has the big, fat "uPD-858" Pll chip, which is not "locked", and can be modded for added frequency coverage. The rest of what's inside is completely different from any NDI radio, but similar to the TRC-457, original President Madison and Washington, the ones with the 4-pin mike socket. President (then called American Radio) also sold a mobile version. The model name? Can't remember. Robyn SB-520D, Cobra 139XLR base radios were also made by Uniden, and had the same main circuit board.
The one heartbreaking weak spot is the tiny Omron MX-3P relay it uses to transfer from receive mode to transmit. A high-mileage radio may have a worn-out relay. Can't get them any more. A sharp horse-trader will know this, and may "harvest" the good relay from a low-mileage radio, putting a worn-out one in before he sells the thing. Look to see if the wire retaining spring is still snapped over the relay. If not, someone could have changed the relay, or removed it to try cleaning the contact points. Seldom helps. Once the thin electroplated layer on those tiny points wears off, no amount of cleaning will make it work for more than a week at a time. A "lost" retaining spring at least tells you someone messed with the relay (for whatever reason), and lost the thing.
The noise blanker is pretty good in these, if it's adjusted right. Tends to bleed from strong nearby stations worse than the blanker found in newer Uniden radios that have the MB8734/8719 PLL chip. Still better than no blanker at all.
__________________ These are not the 'droids you've been looking for.