[Drakelist] cooling fans
Sent this earlier but it bounced as a fwd. Yes..one of the better reasons for having the fan on the back is so it WILL stay cool under a shelf. Fans are excellent idea...even on the rx. They dont have to be on top to work well. m mounted on the rear of the finals cage pulling air out works just as well. Its not really like forced air cooling, all you are doing is removing the warm stagnant air from the cage reducing the temp of the ambient air around the tube envelopes. This allows the tube to shed heat as it was designed to do more effectively. My R4x fan install is in the space between the bandpass box and the transformer and uses a small cardstock duct to pull air from the audio amp area out past the transformer. all runs cool to touch now. t4x top over the finals cage is also always cool. I use the silenx fans..exteremely quiet. See install pics here: https://picasaweb.google.com/captcurt08/DrakeFanInstall Cheers, Curt KU8L ___ Drakelist mailing list Drakelist@zerobeat.net http://mailman.zerobeat.net/mailman/listinfo/drakelist
[Drakelist] Cooling Fans
In the for what it's worth department - I used to hold a muffin fan ATOP my SB-220 and SB-200, with a pair of toothpicks. It made NO permanent holes, held the fan where it did some good, AND I had it sucking out, as opposed to blowing in. Any physics or fluid-mechanics guy will tell you that when you compress a fluid (like air), it heats up (albiet, in this case - very slightly), a negative pressure [sic] tends to lower the temp - whatever works for you, but my fans PULL - they don't PUSH. Tom - W0EAJ ___ Drakelist mailing list Drakelist@zerobeat.net http://mailman.zerobeat.net/mailman/listinfo/drakelist
Re: [Drakelist] Cooling Fans
- Original Message - From: TC Dailey daileyservi...@qwest.net To: drakelist@zerobeat.net Sent: Tuesday, August 23, 2011 11:38 AM Subject: [Drakelist] Cooling Fans In the for what it's worth department - I used to hold a muffin fan ATOP my SB-220 and SB-200, with a pair of toothpicks. It made NO permanent holes, held the fan where it did some good, AND I had it sucking out, as opposed to blowing in. Any physics or fluid-mechanics guy will tell you that when you compress a fluid (like air), it heats up (albiet, in this case - very slightly), a negative pressure [sic] tends to lower the temp - whatever works for you, but my fans PULL - they don't PUSH. Tom - W0EAJ Having a sucking fan on top takes advantage of the normal flow of the heated air due to convection. It also does not blow heated air over the rest of the chassis. Since the amount of air to be moved is not great a low speed fan works fine. Mounting on the back of the final cage works fine despite the theoretical advantage of top mounting (I've tried it). The size of the fan and design of the blades and its speed determine the volume of air it moves and also the amount of back pressure it can work against. Both are not critical at all here. However, the _noise_ a fan makes also depends on size, speed, and blade shape. For the same volume of air a small fan must run faster. Some miniature fans are nearly sirens, they are necessary for some applications but not for cooling fairly large vacuum tube gear so a much quieter fan can be used. I suppose one could devise a physics lab problem of determining both compressional heating and the heating due to frictional forces on the flowing air. That would require measuring a _lot_ of parameters. While this is silly here there are engineering applications where such things _do_ need to be calculated. -- Richard Knoppow Los Angeles WB6KBL dickb...@ix.netcom.com ___ Drakelist mailing list Drakelist@zerobeat.net http://mailman.zerobeat.net/mailman/listinfo/drakelist
[Drakelist] Cooling fans
Wow, the score is about 15 to 0 in favor of cooling fans. I guess the guys that gave me the negatives a number of years ago when I owned a T-4XB aren't a part of this list!! Thanks for all the comments, and yes, I have a cooling fan and will be installing it on my newly purchased T-4XC. Hank___ Drakelist mailing list Drakelist@zerobeat.net http://mailman.zerobeat.net/mailman/listinfo/drakelist
Re: [Drakelist] Cooling Fans
Hi Richard: It is nice now that a lot of the gamers and power PC users want to run silent cooling systems in their machines. Many of the PC fan mfgs rate airflow as well as noise in dB. Silenx utilizes the same blade modeling algorithms previously used for SSBN Boomer propellors. Quietest fans I've ever seen. Curt Richard Knoppow wrote: - Original Message - From: TC Dailey daileyservi...@qwest.net To: drakelist@zerobeat.net Sent: Tuesday, August 23, 2011 11:38 AM Subject: [Drakelist] Cooling Fans In the for what it's worth department - I used to hold a muffin fan ATOP my SB-220 and SB-200, with a pair of toothpicks. It made NO permanent holes, held the fan where it did some good, AND I had it sucking out, as opposed to blowing in. Any physics or fluid-mechanics guy will tell you that when you compress a fluid (like air), it heats up (albiet, in this case - very slightly), a negative pressure [sic] tends to lower the temp - whatever works for you, but my fans PULL - they don't PUSH. Tom - W0EAJ Having a sucking fan on top takes advantage of the normal flow of the heated air due to convection. It also does not blow heated air over the rest of the chassis. Since the amount of air to be moved is not great a low speed fan works fine. Mounting on the back of the final cage works fine despite the theoretical advantage of top mounting (I've tried it). The size of the fan and design of the blades and its speed determine the volume of air it moves and also the amount of back pressure it can work against. Both are not critical at all here. However, the _noise_ a fan makes also depends on size, speed, and blade shape. For the same volume of air a small fan must run faster. Some miniature fans are nearly sirens, they are necessary for some applications but not for cooling fairly large vacuum tube gear so a much quieter fan can be used. I suppose one could devise a physics lab problem of determining both compressional heating and the heating due to frictional forces on the flowing air. That would require measuring a _lot_ of parameters. While this is silly here there are engineering applications where such things _do_ need to be calculated. -- Richard Knoppow Los Angeles WB6KBL dickb...@ix.netcom.com ___ 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
Re: [Drakelist] Cooling fans
I really can't think of a single negative to a cooling fan other than the noise from whatever fan you use. I suppose some could say they are needed since these rigs lasted dozens of years without them, but heat is the enemy of tubes and all the rest of the works. Really quiet, inexpensive low voltage fans were not as readily available in the 60's and 70's as they are today. FWIW Curt KU8L Henry Foglesong wrote: Wow, the score is about 15 to 0 in favor of cooling fans. I guess the guys that gave me the negatives a number of years ago when I owned a T-4XB aren't a part of this list!! Thanks for all the comments, and yes, I have a cooling fan and will be installing it on my newly purchased T-4XC. Hank ___ 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
