Boys and girls... I've got a new pcb that takes care of this problem. Here's how it works
While the circuit has been designed to use either the 6 or 12 v ac filament, When you first turn your radio on, any of the Drake TR series or R series, the fan will come on to high speed. High speed fan is controlled by trimmer R11. The fan will run in high speed for about three seconds and then drop to low speed. That is adjusted by R12. you can set either the high speed or the low speed independently so you have enough voltage to get the fan running, then you slow it down as slow as you want it with just an adjustment of a trimmer. When you transmit, the external key line is pulled to ground and that forces the fan into high speed. This greatly increases the cooling of the PA tubes during tune up and long winded QSOs. When you go back to receive, the fan slows back down to the low setting. The entire pcb about 2 in square is mounted on a side of the pa compartment. There are no wires to cut or holes to drill. installation is completely reversible and operation completely transparent. Mike WB8VGE On Jan 8, 2012, at 10:11 PM, K9sqg wrote: > Another approach I've found to work well is to use a 220 v fan that will > start reliably and run consistently. Super quiet! > > 73, > > Evan, K9SQG > > -----Original Message----- > From: Michael Kelly <mkell...@gmail.com> > To: drakelist <drakelist@zerobeat.net> > Sent: Sun, Jan 8, 2012 4:57 pm > Subject: [Drakelist] Fans > > Okay here's another way to go at the fan plan question .... I wire two 110 > vac > fans in series so they run half speed. I can't hear them at all yet they move > a > good deal of air. > > The one above the finals on my TR4Cw is blowing straight up and the one in > the > front top in the middle is blowing in. I get a "circular" air flow pattern > and > the entire transceiver never even approaches warm. Just to make sure, (and > for > fun) I have a thermometer on top of the fan which sets on top of the one on > the > finals and the temperature hardly changes at all. > > To keep the fans stationary I use 4 pieces of coax seal rolled in a ball > about > half the size of a pea to serve as "feet" on each corner of the fan. It won't > stick permanently but it will keep the quite stationary. > > So for me the question of blow out or in is answered by doing both .... > > As for providing power I have both the AC-4 and these series wired fans in a > 3 > way plug which is in turn plugged into a soft start circuit. Turn on the slow > start switch turns on both the AC-4 and the fans. > > Try the two fan approach ... No need to modify anything in the transceiver. > Cooler is better, eh? > > Happy New Year everyone. > > Michael n4mak > > Sent from my iPhone > //////////////////////////////////////////////////////////// > ////////////////////////////////////////////////////////////// > > > > At 07:45 PM 1/8/2012, Steve Wedge wrote: > >> I've done all which-ways. > >> > >> I once used a 120V fan and used a big, honkin' wire-wound resistor to slow > >> it down. > >> I currently use a 12V fan with a thermistor over my finals, running off a > >> 12V wall wart. the fan runs really slow until the temp gets to the point > >> where the thermistor lets it go for full-speed. This fan cost me $5 at a > >> hamfest. > >> I've worked on a couple of R-4B's where the previous owner tapped off the > >> filament supply with a diode and cap (half-wave rectifier). The fans he > >> used are a little louder than my Xmitter fan. > >> If you opt for using on-board power, you can tap off the filament supply > >> for 12V and feed it to an RCA jack in the SPARE location, or just feed > >> wires through that hole. I like just setting the fan on top, using rubber > >> feet. No holes get drilled that way... > >> > >> YMMV, > >> > >> Steve Wedge, W1ES/4 > >> > >> Live free or die: Death is not the worst of evils. > >> John Stark. > >> > >> All my computers have my signature with various pearls of wisdom appended > >> thereto. > >> > >> From: <mailto:mtruss8...@comcast.net>Michael & Sue Trussell > >> Sent: Saturday, January 07, 2012 5:33 PM > >> To: <mailto:drakelist@zerobeat.net>drakelist@zerobeat.net > >> Subject: [Drakelist] Need a fan for my T-4XC Transmitter? > >> > >> I need to replace my old 30 year old 110 volt fan on my transmitter. I > >> know a few of you have used the twelve 12 volt fans and some have used the > >> 110 volt version. What I would like to know where I can get power so I > >> don't have to plug the fan in every time I turn the rig on. I would like > >> the fan to come on when I turn on the power to the transmitter, any > >> suggestions? > >> > >> Thank you in advance > >> > >> Michael J Trussell KA8ASN > >> > >> > >> ---------- > >> _______________________________________________ > >> Drakelist mailing list > >> Drakelist@zerobeat.net > >> http://mailman.zerobeat.net/mailman/listinfo/drakelist > >> _______________________________________________ > >> Drakelist mailing list > >> Drakelist@zerobeat.net > >> http://mailman.zerobeat.net/mailman/listinfo/drakelist > > > > ///////////////////////////////////////////////////////////////////////////////////////////////////////////////////////// > > _______________________________________________ > Drakelist mailing list > Drakelist@zerobeat.net > http://mailman.zerobeat.net/mailman/listinfo/drakelist > _______________________________________________ > Drakelist mailing list > Drakelist@zerobeat.net > http://mailman.zerobeat.net/mailman/listinfo/drakelist
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