I mount heavy stuff at the bottom of the rack, lighter stuff working upwards. Heat rise is incidental to my overall systems, those components are designed to take it. Yes, fans move the ambient temperature around. In the grand scheme of things, it has never been an issue for me. VHF duplexers and cavities are rarely mounted in the same rack as the transmitters due to size alone.
Barry C' wrote: > In my industry we also use rack mounting which is quite the reverse , with > fan forced air flow to move the heat so in my experience I stick by the > comments .Frankly having just installed a 3000 va ups here recently I prefer > it being off the floor anyway . > > To: Repeater-Builder@yahoogroups.com > From: [EMAIL PROTECTED] > Date: Sat, 24 Nov 2007 16:14:59 -0800 > Subject: RE: [Repeater-Builder] 19" rack positioning question > > > > > > > > > > > > > > > > > > > > > Barry, > > > > With all due respect, I think the appropriate response to your statement is: > > "Not necessarily." > > > > The typical Motorola Micor 100 watt repeater station will have the duplexer > > at the very bottom of the cabinet, with the power supply just above it. > > Then follows the unified chassis, and finally the 100 watt PA at the top. > > > > While your desire for cooling fans is well-intended, I daresay that the vast > > majority of 100 watt Micor stations- many of which remain in service today- > > are cooled solely by convection, and they seem to survive without fans. > > > > Let us keep in mind that fans do not "cool" anything; they simply move air > > around. If the ambient temperature in an uncooled transmitter shack is 120 > > degrees Fahrenheit, the fan will simply raise the temperature inside the > > cabinet to 120 degrees F- which might be higher than the temperature inside > > the cabinet if no fans were used. > > > > 73, Eric Lemmon WB6FLY > > > > > > -----Original Message----- > > From: Repeater-Builder@yahoogroups.com > > [mailto:[EMAIL PROTECTED] On Behalf Of Barry C' > > Sent: Saturday, November 24, 2007 3:37 PM > > To: repeater-builder@yahoogroups.com > > Subject: RE: [Repeater-Builder] 19" rack positioning question > > > > Just remember heat rises so the hottest items usually go high in the stack , > > assuming you have a top mounted fan. > > > > ________________________________ > > > > To: Repeater-Builder@yahoogroups.com > > From: [EMAIL PROTECTED] > > Date: Sat, 24 Nov 2007 18:50:41 +0000 > > Subject: [Repeater-Builder] 19" rack positioning question > > > > > > In the sprit of the only stupid question is the one that goes un- > > asked. > > Here goes: > > I have a Micor UHF repeater mounted in a 46" x 19" cabinet. > > It is now a ham band repeater that I have added a new NHRC-5 > > controller and IRLP interface. The modules are mounted as follows: > > Top: Custom built 12V PA cooling fan rack controlled by the NHRC-5 > > aligned with the top door vents. > > 75W PA > > Transmitter/ Antenna Network > > Control module (mostly empty now replaced with NHRC-5 and mods from > > this site) > > Receiver module > > Massive TPN1110B power supply > > 4" space > > Bottom: WaCom duplexer cannisters (4) > > I would like to put the power supply on the bottom so that it aligns > > > > with the vents in the cabinet doors and I can add some fans to cool > > the transformer (you can cook a grilled cheeze sandwitch on it) An > > added plus is that it will make the cabinet more stable with the > > weight on the bottom. > > Is there any issues mounting the duplexers between the receiver and > > the power supply with the powersupply on the bottom. > > I hate to move things around and have problems. > > And yes I will get help to lower the power supply and save some > > digits. I know the best solution is to replace the powersupply with > > a > > more modern one. I plan to do this when funds are better. When this > > time comes who makes the best replacement powersupply unit? (ok two > > Questions) > > Thanks gang > > Bill N5ZTW > > > > > > > > > > > > ________________________________ > > > > Sell your car for just $30 at CarPoint.com.au. It's simple! > > <http://a.ninemsn.com.au/b.aspx?URL=http%3A%2F%2Fsecure%2Dau%2Eimrworldwide% > > 2Ecom%2Fcgi%2Dbin%2Fa%2Fci%5F450304%2Fet%5F2%2Fcg%5F801459%2Fpi%5F1004813%2F > > ai%5F859641&_t=762955845&_r=tig_OCT07&_m=EXT> > > > > > > > > > > > > > > > > > > > > > > > > > _________________________________________________________________ > New music from the Rogue Traders - listen now! > http://ninemsn.com.au/share/redir/adTrack.asp?mode=click&clientID=832&referral=hotmailtaglineOct07&URL=http://music.ninemsn.com.au/roguetraders
