Joe, Many thanks.
John -----Original Message----- From: Repeater-Builder@yahoogroups.com [mailto:[EMAIL PROTECTED] On Behalf Of Joe Sent: Saturday, April 26, 2008 8:33 PM To: Repeater-Builder@yahoogroups.com; [EMAIL PROTECTED] Subject: Re: [Repeater-Builder] Cooling fan Here is a circuit that I used on my old 220 repeater. This may be what you need, simple and effective. 73, Joe, K1ike Attachment sent direct to you. John Transue wrote: > > Thanks to all who responded to my request for help to control a > cooling fan. I now have several workable choices. > > John Transue > > > > -----Original Message----- > *From:* Repeater-Builder@ <mailto:Repeater-Builder%40yahoogroups.com> yahoogroups.com > [mailto:Repeater-Builder@ <mailto:Repeater-Builder%40yahoogroups.com> yahoogroups.com] *On Behalf Of *TGundo 2003 > *Sent:* Saturday, April 26, 2008 12:15 PM > *To:* Repeater-Builder@ <mailto:Repeater-Builder%40yahoogroups.com> yahoogroups.com > *Subject:* Re: [Repeater-Builder] Cooling fan > > > > > I use the System 3 fan kit from Active Thermal Management: > > http://www.activeth <http://www.activethermal.com/System_3.htm> ermal.com/System_3.htm > <http://www.activeth <http://www.activethermal.com/System_3.htm> ermal.com/System_3.htm> > > Power it with a separate power supply (the included wall wart, though > I will be changing that someday when I ) and have never had a problem. > I mount the 100 degree thermal switch to the heat sink of the PA and > call it a day. Using this arrangement on a UHF Mitrek mobile converted > repeater and on a CDM 1550 being used as a link radio. > > Tom > W9SRV > > --- On Sat, 4/26/08, [EMAIL PROTECTED] <mailto:no6b%40no6b.com> <mailto:no6b%40no6b.com> > <[EMAIL PROTECTED] <mailto:no6b%40no6b.com> <mailto:no6b%40no6b.com>> wrote: > > > From: [EMAIL PROTECTED] <mailto:no6b%40no6b.com> <mailto:no6b%40no6b.com> <[EMAIL PROTECTED] <mailto:no6b%40no6b.com> > <mailto:no6b%40no6b.com>> > > Subject: Re: [Repeater-Builder] Cooling fan > > To: Repeater-Builder@ <mailto:Repeater-Builder%40yahoogroups.com> yahoogroups.com > <mailto:Repeater-Builder%40yahoogroups.com> > > Date: Saturday, April 26, 2008, 10:49 AM > > At 4/26/2008 02:48, you wrote: > > > > >Hi, > > > > > >Have tried a few ex equipment and CPU cooler fans on a > > p/a heatsink > > >but all generate a noise (light buzz) on the > > transmitted signal. > > > > > >Can anyone suggest the correct choice of fan (or what I > > am missing) to > > >stop the buzz on the transmitted signal? > > > > > >RF choke? Tried cap up to 4700uf little change? > > > > I've started using PTT-switched CPU fans on G.E. MVPs > > for cooling. On the > > VHF MVP they are quite effective, allowing full power > > continuous duty > > operation. On UHF the thermal margins are a bit thin due > > to the lower > > efficiency of the UHF RFPA. I have noticed the same noise > > you > > observed. At first I keyed the fans off the PTT line, > > & I found that by > > providing a separate dedicated switched voltage the noise > > was greatly > > reduced. I suspect adding the L-C or R-C filtering to the > > supply side of > > the switch would probably knock out any remaining noise. > > > > Bob NO6B > > > > > > ------------------------------------ > > > > > > > > Yahoo! Groups Links > > > > > > > > __________________________________________________________ > Be a better friend, newshound, and > know-it-all with Yahoo! Mobile. Try it now. > http://mobile. <http://mobile.yahoo.com/;_ylt=Ahu06i62sR8HDtDypao8Wcj9tAcJ> yahoo.com/;_ylt=Ahu06i62sR8HDtDypao8Wcj9tAcJ > <http://mobile. <http://mobile.yahoo.com/;_ylt=Ahu06i62sR8HDtDypao8Wcj9tAcJ> yahoo.com/;_ylt=Ahu06i62sR8HDtDypao8Wcj9tAcJ> > > > __________ NOD32 2918 (20080303) Information __________ > > This message was checked by NOD32 antivirus system. > http://www.eset. <http://www.eset.com> com > > __________ NOD32 2918 (20080303) Information __________ This message was checked by NOD32 antivirus system. http://www.eset.com
