"Dennis Monticelli" <[EMAIL PROTECTED]> made an utterance to the drakelist gang ---------------------------------------------------------------------- Just a moderate amount of air assist makes a big difference in terms of reducing peak component temp, reducing temp gradients, and minimizing temp change between TX and RX modes.
As for the Drakes being built to run at that elevated temp and performing worse if run cooler, I find that very hard to believe. The only scientific basis I can find for it (and a weak argument at that) is non-linear temp correction was used in the design. In other words, parabolic parameter change with temp for certain temp compensation components was established at a given elevated temp. But this degree of sophistication of temp correction was probably beyond the bag of tricks at the disposal of the Drake designers at the time. And it does not explain that temp reduction properly done will also reduce temp change and that helps out any circuit, however the temp compensation is performed. Bottom line, cool the sucker. It will live long and prosper. Dennis AE6C On Dec 24, 2007 9:11 PM, Garey Barrell <[EMAIL PROTECTED]> wrote: > > Garey Barrell <[EMAIL PROTECTED]> made an utterance to the drakelist gang > ---------------------------------------------------------------------- > Peter - > > I haven't, but I can tell you that the cabinet top of the T-4X(any) can > be too hot to comfortably hold you hand on it after extended > transmission, especially on high duty cycle modes such as RTTY and AM. > Even on CW or SSB this area can get quite warm. Of course this is even > more evident with the TR-3/4 series with 50% more dissipation in only a > slightly larger cage. > > On the other hand, with a small, silent fan exhausting air out the back > of the PA cage the cabinet top is only slightly warmer than the rest of > the cabinet, even after long transmissions. The fan really makes a big > difference in that area, and in the rest of the cabinet as well. > > 73, Garey - K4OAH > St Charles, IL > > > Peter Bent wrote: > > "Peter Bent" <[EMAIL PROTECTED]> made an utterance to the drakelist gang > > ---------------------------------------------------------------------- > > Just curious, has anyone actually measured the temps in the cages-- before > > and after? > > > > -----Original Message----- > > From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On > > Behalf Of Ron Wagner > > Sent: Monday, December 24, 2007 8:18 PM > > To: [EMAIL PROTECTED] > > Subject: Re: [drakelist] Cooling Fan on finals > > > > > > Ron Wagner <[EMAIL PROTECTED]> made an utterance to the drakelist gang > > ---------------------------------------------------------------------- > > The way I went about his was a half wave (single diode) and filter cap > > from the 12VAC filament line. I drive a 24 volt fan drawing air out of > > the final cage. Turns the fan on as I turn on the rig, shuts down when > > turned off. Runs slow and quit, but really makes a difference on the > > temp of the final cage. I attach the fan to the rear of the cage (so the > > cabinet comes off without problems) with grommets and black nylon wire > > ties. This arrangement does not seem to damage the cabinet, and does a > > nice job cooling. > > > > As far as stability, as long as you do not blow the warm air in, it should > > make the rig more stable. The cabinet and associated circuits should > > stay much more constant in temperature. In a good oscillator design, > > which Drake has, it is typically temperature change that causes the drift. > > > > 73, > > Ron WD8SBB > > > > > > ---------------------------------------------------------------------- > Submissions: [EMAIL PROTECTED] > Unsubscribe: [EMAIL PROTECTED] - unsubscribe drakelist in body > Hopelessly Lost: [EMAIL PROTECTED] - help in body of message > Zerobeat Web Page: www.zerobeat.net - sponsored by www.tlchost.net > ---------------------------------------------------------------------- > ---------------------------------------------------------------------- Submissions: [EMAIL PROTECTED] Unsubscribe: [EMAIL PROTECTED] - unsubscribe drakelist in body Hopelessly Lost: [EMAIL PROTECTED] - help in body of message Zerobeat Web Page: www.zerobeat.net - sponsored by www.tlchost.net ----------------------------------------------------------------------
