The AM Forum

Hello: Dose anyone know where I can order an assortment of pearl tube coolers all sizes but the small tube size is what I need now.

John W9BFO

http://www.partsconnexion.com/tube_cool_pearl.html

A fan probably would be just, if not more, as effective. Tubes are supposed to get hot.

Thanks pete those 6GW8 tubes run very hot on transmit I have used the coolers in the past and they save tubes. 

John W9BFO

Hmmm...  they sell the PCF-250 for 813s.  The temperature reduction curves look like it actually works. Interesting.

I'll bet one of the smaller ones wud fit a 4D32, one of my favorites.  

Didn't see any for a 4-1000A.... ;D

Yes, a fan would probably be better since the radiation cooling wouldn't be blocked by the fins.  Still, I wonder if adding fins to an existing fan-cooled tube would make it cooler?  (A tube without a chimney, of course)

T

You could get them direct from Bill Pearl too, I expect.
He's online afaik, has web presence.

Knowing him, he may be willing to do custom sizes...

                 _-_-

Yep, they do get hot, but the 6GW8 tubes are very robust. I've never lost one due to heat exhaustion in rigs or in Hi-Fi amplifiers. As I said somewhere, a suck-out fan sitting on the top of the rig, will pull the heat out and also provide some air circulation.  Also, as I said somewhere, in the case of the HA-410 or 460, the underside of the chassis gets very hot too due to several high wattage resistors. The HA-410 and 460 cabinets use dimples as feet on the bottom. The bottom of the cabinet has vent holes but the dimples don't really raise the cabinet up enough to vent the heat. On both my HA-410 and 460, I installed some big boy feet to raise the cabinets up.

Some mobile? VHF gear used coolers. I think I cannibalized a Motorola chassis and found one over a fat RF tube, arranged so that the cooler transferred heat from the envelope directly to a big block of metal having a cylindrical hole. The cooler was not the finned kind like the pearl but made of a tube of slightly springy expanded metal and fit snug between the tube envelope and the heat sink so as to conduct heat. Some lab gear uses coolers, and coolers are used on 6080's in lots of gear, especially when there is but one smallish fan. I believe in coolers where they can be useful.

Beware of marketing fluff though. Pearl used the term "skyrocketed" to describe tremendous life time gains (12K hours on a 6005) in their marketing document "Complete Overview of Tube Coolers - PDF", but the test was with only 6 individual tubes and the temperature gradient graph for this test didn't show actual envelope temperatures, while other graphs did show them. Another benefit is "Greater transparency and an increase in the air and space around and between performers, produced a noticeable increase in presence. At the same time, a further improvement in low level dynamics made instruments more vibrant and real." The increase in air space between performers might be very useful for DX.