The Trak D300 is a Uniden Washington/Cobra 142GTL in a nicer cabinet, with larger channel digits. The D300 also has a channel-9 monitor board. Other than the name, and a pretty face, it's a bare-bones SSB CB base radio. Not a bad radio, but one that is over 25 years old, guaranteed.
About the Dak Mark X, where to begin? It's what I call a "Cha-Ching" radio. Guaranteed to cost a mint to fix when (not if) it breaks down. Here's a post I recycled from where I posted it on another forum on the subject.
Hmmmm..... So how much bad news can you stand at one time?
Important parts of the Dak ten were radically UNDER-designed. The skinny tube serves as the transmit driver, and the fat one is the final amplifier stage.
The AM transmit modulator is a solid-state circuit. Two small TO-220 audio transistors drive into a
transformer, which steps up the audio voltage to modulate the tube final. Trouble is, this modulator
stage AND the transistor that regulates the 13.5 Volt DC power supply section are ALL THREE bolted
to a tiny piece of half-inch aluminum angle bracket. This is a woefully tiny heat sink for all that power.
If you turn the AM modulation down to around 90% as directed in the manual, it will survive for
around a year before blowing out. Turn it up, and "POOF", the AM modulator and regulator transistor will repeatedly overheat and blow out.
Here is one solution to this problem. A large, metal power transistor gets mounted on a large heat
sink, and three wires are run to the circuit-board holes where the old regulator transistor was pulled
out. Another large heat sink with two oversize transistors serves to take the place of the original
plastic TO-220 modulator transistors. The original driver next to each of these also gets replaced,
each with one the size of the original modulator.
The pic above shows the old and new, side-by-side.
The rectifiers for the 13.5-Volt DC supply are also way too small. A generic 25-Amp bridge rectifier can
be bolted to the side rail of the chassis, alongside where the original rectifier diodes were removed.
Here's a view of the new heat sinks, one for the regulator on the right, and the modulators on the left mounted on the inside of the rear panel.
And this leaves only:
-> The channel selector,
-> Failure-prone channel digits,
-> Numerous electrolytic capacitors that fail,
-> And chronic solder-connection failures to fill in the rest of the picture, so to speak.
Oops. Gotta shrink that last image. Spills off the right side of the screen too far.
Any more rain I can dribble onto your parade?
It's not the years, it's the miles, too. If a radio has little or no wear and tear on it,
the price to put it back on the air will be lower.
A 1977 car won't be a reliable daily driver even if it's "Show Room Mint". Some things just don't last
that long. If the radio has had maintenance and upgrades already done to it, you probably won't
have to repair it more than once a year or so.
And if it's all still "original" on the inside, it'll be a lot more frequent than once a year.
73