Figure 1: The “caulk tube fix” can be seen behind the transformer.
My Trusty Ten Tec 260 power supply is a nice hefty one: – it’s capable of delivering 28 amps, and that’s enough to power any of my radios with ease. Unfortunately, the supply developed the “old power supply” malady of producing slightly less-than-well-filtered DC power. The first thought for me was that the problem was in the electrolytic capacitors. I checked the caps with my brand new ESR meter and a capacitor checker. Oddly, the caps all seemed to check out OK.
Still, it seemed to me that the main filter capacitor was the culprit, because the poor filtering was a problem dependent on load. I grabbed my keyboard. Soon I was clicking my way through Mouser Corporation’s online menu until I landed on a page that detailed a capacitor with similar specs to the original one. I was surprised that the 24,000 uF Mouser number 598-DCMC50V263 / Mfg number DCMC263U050AC2B was only a $26 dollar item. I was expecting to pay about twice that amount. The only problem was that the physical dimensions of the new cap were correct so far as height was concerned, but it was smaller relative to the original part’s diameter. What to do?
Grab an old used-up tube of caulk, of course! I cut a four inch length of the old tube (making sure there was no residue left inside of it) – and grabbed an oversize rubber grommet from the junk drawer. Voila – the capacitor could fit inside of the tube and grommet, which itself could be secured by the original clamp on the bottom of the chassis. The grommet is a super tight fit, so the capacitor is solidly held in place.
The next thing to do was to power up the supply and see if the filtering was any better. When I did this, the supply voltage went up a little compared to what it had been with the old cap sitting in the chassis. I tweaked the voltage downwards to 13.8 VDC by adjusting R12 on the control board.
Figure 2 : Another shot of the cap fix
The power supply proved to be back to its scrubbed up old self, producing once again that nice clean DC power with which to make my Omni, Triton, and Corsair radios sing out the good notes.
In retrospect, the original Mallory capacitor would have been easier to install, but AFAIK – it’s not made any more. Maybe Mouser has another product with dimensions closer to the orignal, but I didn’t look that hard to find it. I was impressed by the price of the one that I did find. There are NOS (new old stock) Mallory parts to be found on Ebay – but old caps might bring back the same “old” problem, pun intended. LOL –
Figure 3: I suppose I could have painted the tube to make it less obvious that it’s from my paint bin!
Note / Disclaimer: The author does not provide any of the foregoing as advice. This page has been presented as the work of a hobbyist, and is not meant to be advice or design matter for others to duplicate. Readers should look elsewhere for design advice and info. This is just a journal for what I do with my hobby.
WB8LZR 