This is not about a Ty Pennington one week build a new home as seen currently on Netflix. But this posting is about making over commercial radios where the by-product is an improvement over the original.
Inherent in such an undertaking is the ability to look at the commercial radio and spot the possibilities.
There are four commercial radios where I have done this and the results were indeed much better than when they came off the Factory Floor.
Heathkit HW-101 with a Digital Display and VFO Stabilizer
Ten Tec Triton IV Model 540 converted to a Model 544 (Digital Display)
Keypad Operation of a Ten Tec Model 150A
The FPM-300 was the last SSB Transceiver off of the Hallicrafters line. A Hybrid design, it was intended for Fixed, Portable and Mobile Operation (FPM) with a built-in power supply that would operate off of 115AC and 12VDC.
It was a piece of junk! The VFO drifted and it was unreliable. I purchased a stock unit cheap and after some months simply gave up trying to fix the many problems. I kept the main board which was all solid state and the S Meter, and the rest was sold as parts on eBay. It felt good as my net loss was only $20 but actually it only cost me $20 to have the basis of a really excellent transceiver.
Essentially, I took the main board which had the Crystal Filter Mic amp, VOX, Balanced Modulator/Product Detector and the IF stages and built the rest of the circuits around those elements.
My adds included the Band Pass and Low Pass Filter, Audio Amp, the Digital LO/BFO, the Driver Stage, the Receiver RF Amp Stage and the Final RF Amp.
Hallicrafters had a power supply board that had a whole series of weird low voltages for various parts of the radio -- that had to be duplicated as well.
The Band Switch in the lower right corner selects the bands and also at the same time selects the proper BPF and LPF for that band. That Band Switch Dial Plate was cut on my CNC -- a new learning experience for me to boot.
The hardest task was collecting information of what goes where on the 44 Pin Edge card connector that mates with the main board. The main board in the factory radio was vertical and plugged into a sub-chassis. In my build I elevate the 44 Pin Connector so that the main board would plug into the board horizontally.
A ham I know worked on the FPM300 line and after hearing my version said it was perhaps better than what they were churning out of the factory.
This build was as much Mechanical Design as it was the electronics.
The suggestion here is that some of the old boat anchors can be "made over" and used with confidence on today's ham bands. This radio has been used on FT-8 using my external digital adapter design.
WYKSYCDS!
73's
Pete N6QW