Re: [drakelist] Cooling Fan on finals
Howard Traxler [EMAIL PROTECTED] made an utterance to the drakelist gang -- Well yes, I'm sure it will live longer; not sure about prosper. A friend gave me that thought in 1969; just a something to think about. He's dead now. Thought I'd throw it out for comments and I got some, thanks. I think I'll look for a couple little fans. WA9RYF - Original Message - From: Dennis Monticelli [EMAIL PROTECTED] To: [EMAIL PROTECTED] Sent: Tuesday, December 25, 2007 12:01 AM Subject: Re: [drakelist] Cooling Fan on finals : : 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
[drakelist] Cooling Fan on finals
Howard Traxler [EMAIL PROTECTED] made an utterance to the drakelist gang -- A-way back in the day, when my first Drake twins were new to me--that would be the late 60's--I was told that the xmtr was designed to run at that temperature and that I'd have drift problems if I ran it cooler. I never did any hard core testing to find out. WA9RYF - Original Message - From: [EMAIL PROTECTED] To: [EMAIL PROTECTED] Sent: Monday, December 24, 2007 1:18 PM Subject: Re: [drakelist] Confessions of an Appliance Operator : [EMAIL PROTECTED] made an utterance to the drakelist gang -- : I use specially selected 220v fans that start and run reliably at 110 v. : Can't hear them and they are the ones I use on L4B/L7 power supply : upgrades/rebuilds. : : Merry Christmas from a politically incorrect Drake enthusiast! : **See AOL's top rated recipes : (http://food.aol.com/top-rated-recipes?NCID=aoltop000304)-- 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 -- No virus found in this incoming message. Checked by AVG Free Edition. Version: 7.5.516 / Virus Database: 269.17.8/1195 - Release Date: 12/24/2007 11:19 AM -- 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 --
Re: [drakelist] Cooling Fan on finals
Jim Shorney [EMAIL PROTECTED] made an utterance to the drakelist gang -- On Mon, 24 Dec 2007 15:27:52 -0600, Howard Traxler wrote: I was told that the xmtr was designed to run at that temperature and that I'd have drift problems if I ran it cooler. Aside from Evan's comments, that doesn't seem to follow intuitively. I would think that sucking hot air out of the back of the radio would crete a more stable temperature environment inside the radio across the changes in heat generated from RX to TX. With (theoretically) the most stable temps being the farthest away from the final cage. What's in the opposite corner of the transmitter from the final cage? The PTO! Seems to me that cooling the radio would reduce drift. Aside from that, it's a scientific fact that ANY electronic component (not just toobs) will last longer when run cooler. I would prefer to err on the side of component life. 73 -Jim -- Ham Radio NU0C TR7/RV7, TR6/RV6, T4XC/R4C, L4B, NCL2000, SB104A, R390A, GT550A/RV550A, HyGain 3750, IBM PS/2 - all vintage, all the time! HyGain 3750 User's Group - http://groups.yahoo.com/group/HyGain_3750/ -- 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 --
Re: [drakelist] Cooling Fan on finals
Garey Barrell [EMAIL PROTECTED] made an utterance to the drakelist gang -- Amazing how much mis-information flows over the internet!! Temperature stability is a function of temperature CHANGE, not absolute temperature. The reason a temperature controlled oscillator is NOT because it is heated, but because the heat is held constant by an internal, tightly temperature controlled heater. Adding a fan to any electronic equipment, especially tube based equipment, will increase the life of the tubes and components, AND will also keep the temperature constant because of the constant flow of air. Again, the object is to stabilize the temperature, not raise or lower it, to maintain frequency stability. A T-4X(any) will change cabinet temperature considerably from receive to transmit when there is no fan cooling. This is minimized by the addition of a fan, blowing air __OUT__. The object is to assist the normal convection cooling, (hot air rises,) by forcing air AWAY from the transmitter final compartment, AND the rest of the transmitter. Blowing air IN forces heated air throughout the chassis, including the PTO, causing the temperature to VARY, not stabilize. Blowing air into the transmitter reduces the heat in the final compartment, but INCREASES the heat everywhere else, varying the temperature of the PTO as well. The TR-7 is DESIGNED to have air drawn out of the chassis, for the same reasons, and the heatsink is DESIGNED to have air drawn past it as well. The cooling SYSTEM is designed to transfer heat from the final transistors to the heatsink to air being blown AWAY from the area. You can hold a small source of smoke, (candle, incense stick, etc.,) near any of the cabinet slots and smoke will be drawn INTO them when the fan is installed as designed, blowing OUT. Merry Christmas!! 73, Garey - K4OAH St Charles, IL Drake 2-B, 4-B C-Line Service Supplement CDs www.k4oah.com [EMAIL PROTECTED] wrote: [EMAIL PROTECTED] made an utterance to the drakelist gang -- Not sure I understand that comment about the drift, hi hi. The drift is a function of the thermal environment with respect to the PTO components, including any negative temperature compensating capacitors. While the transmitter will work, it will have a warm up period, and then cycles up and down as a function of the transmit duty cycle. Compensating for the former is enough of an engineering challenge, but the latter, for tube gear of the 60s, well, it is harder to address although there were some good designs out there. From a theoretical perspective, I'm not sure why the rig would run better when it is hot. A temperature compensated crystal oven obviously works better at higher stabilized temperature (above room ambient) but conventional circuits, well I'm not sure. Drift aside, the tubes will last longer with improved cooling though. -- 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 --
RE: [drakelist] Cooling Fan on finals
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 --
