Here’s the 4th page of videos [Split into 3 sections] in the Command Technologies HF-2500 teardown and rebuild by Steve G0UIH – Vortex Antenna Systems/Q82.uk. Here in Part 4, we’ve plenty of images taken whilst stripping down the PSU and main QRO band switch.
We focus on taking out the old electrolytic capacitors which are obviously ‘well past their sell-by date‘ and replacing them with much higher spec modern alternatives.
The resistors in the front plate meter network are also faulty with a 1 meg 2w being open circuit, a 200ohm 10w also being open circuit and a wrong value 10k ohm [should have been 150k] fitted at the factory when new. I’ve replaced [ALL] the old 2w carbons in favour of more modern Ohmite MOX500 variants and have a new Vishay/Dale 200ohm 10watter installed to replace an ‘open circuit’ cracked original.
See the Video Part 4 – PSU Stripdown/Rebuild and Main Band Switch Repair
See the Video Part 4a – PSU Board Component Investigation + RX/TX Relay Location
See the Video Part 4b – PSU Board – Bad 200ohm 10w Resistor
Click on any of the images below for a larger hi-res version.
Our New Upgraded Version is 105 Degrees C, +25% More Ripple Handling and Low ESR
See Video Part 4b for a rundown of the problem
Schematic Shows 150k Ohm 2 Watts. The Fitted One was 10k Ohm [this was also replaced].
A modern [much better] alternative. 3 x 1Meg Ohm and 1 x 150k Ohm – Tnx Tom W8JI for the recommendation
Check out Tom’s site at CTR Engineering in the USA
