[Repeater-Builder] Cooling fan
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? Thank you, Doug - GM7SVK
Re: [Repeater-Builder] Cooling fan
We have found that 12v. fans do cause interference with our link transmitters for the NYC voting network. The solution we found is taking one of the 2 power supply chokes from an old Micor mobile radio and using it in series with the 12v. lead to the fan, add a cap. 2000 mfd or larger from fan to ground and the level of AC imposed on the power lead drops from nearly 4 VOLTS to less than 10 millivolts...Resulting in a totally clean carrier. lance N2HBA - Original Message - From: Doug Hutchison To: Repeater-Builder@yahoogroups.com Sent: Saturday, April 26, 2008 4:48 AM Subject: [Repeater-Builder] Cooling fan 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? Thank you, Doug - GM7SVK -- No virus found in this incoming message. Checked by AVG. Version: 7.5.524 / Virus Database: 269.23.4/1397 - Release Date: 4/25/2008 7:42 AM
Re: [Repeater-Builder] Cooling fan
I have found that adding a resistor in series with the fan and a capacitor across the fan will do the same job as an inductor and capacitor without taking up as much space. The value of resistor I use is just enough to drop the voltage by about 1/2 volt. For a fan drawing 0.5A, use a 1 ohm 1W resistor. For other current draws adjust accordingly. It is not critical. The fan speed will not change much - 12vdc fans will run as low as 6-7v normally. Burt VE2BMQ Captainlance wrote: *We have found that 12v. fans do cause interference with our link transmitters for the NYC voting network. The solution we found is taking one of the 2 power supply chokes from an old Micor mobile radio and using it in series with the 12v. lead to the fan, add a cap. 2000 mfd or larger from fan to ground and the level of AC imposed on the power lead drops from nearly 4 VOLTS to less than 10 millivolts...Resulting in a totally clean carrier. * *lance N2HBA* - Original Message - *From:* Doug Hutchison mailto:[EMAIL PROTECTED] *To:* Repeater-Builder@yahoogroups.com mailto:Repeater-Builder@yahoogroups.com *Sent:* Saturday, April 26, 2008 4:48 AM *Subject:* [Repeater-Builder] Cooling fan 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? Thank you, Doug - GM7SVK
Re: [Repeater-Builder] Cooling fan
Doug, I've experienced the same with 12 VDC fans. Don't have a solution. I use 120 VAC fans, but if you want battery backup might not be your solution. 73, ron, n9ee/r From: Doug Hutchison [EMAIL PROTECTED] Date: 2008/04/26 Sat AM 04:48:54 CDT To: Repeater-Builder@yahoogroups.com Subject: [Repeater-Builder] Cooling fan 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? Thank you, Doug - GM7SVK Ron Wright, N9EE 727-376-6575 MICRO COMPUTER CONCEPTS Owner 146.64 repeater Tampa Bay, FL No tone, all are welcome.
RE: [Repeater-Builder] Cooling fan
Doug, I suggest that you do one or both of the following: Buy a small cooling fan that is clearly marketed as one with low EMI, or buy s small fan that runs at the lowest speed possible. My UHF solar-powered repeater has a 45 watt Motorola R1225 transceiver that is cooled by a Panasonic low-EMI fan that runs around 1100 RPM when operated at its rated input voltage. It is controlled by a 120-degree thermal switch mounted on one of the radio's cooling fins. When the fan is running, there is zero noise modulation of the carrier. The solution is definitely NOT to run a 24 VDC fans at 12 volts, because that often makes the current pulse higher in amplitude. The key is to choose a fan that runs so slowly at its design voltage, that the commutation pulses fall below the audible range. If you can hear an audible whine from the fan in a quiet room, it's running too fast. When a low-EMI fan is chosen, those pulses will be at a very low amplitude. Finally, the circuit that powers the fan should be connected directly at the power source, rather than sharing the same power leads as the radio. 73, Eric Lemmon WB6FLY -Original Message- From: Repeater-Builder@yahoogroups.com [mailto:[EMAIL PROTECTED] On Behalf Of Doug Hutchison Sent: Saturday, April 26, 2008 2:49 AM To: Repeater-Builder@yahoogroups.com Subject: [Repeater-Builder] Cooling fan 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? Thank you, Doug - GM7SVK
Re: [Repeater-Builder] Cooling fan
I have been able to eliminate the noise by using a power supply that does not support the repeater. I have even used the cheap wall wart types to power the fans with no noise generated to the repeater. JIM KA2AJH - Original Message - From: Captainlance To: Repeater-Builder@yahoogroups.com Sent: Saturday, April 26, 2008 9:12 AM Subject: Re: [Repeater-Builder] Cooling fan We have found that 12v. fans do cause interference with our link transmitters for the NYC voting network. The solution we found is taking one of the 2 power supply chokes from an old Micor mobile radio and using it in series with the 12v. lead to the fan, add a cap. 2000 mfd or larger from fan to ground and the level of AC imposed on the power lead drops from nearly 4 VOLTS to less than 10 millivolts...Resulting in a totally clean carrier. lance N2HBA - Original Message - From: Doug Hutchison To: Repeater-Builder@yahoogroups.com Sent: Saturday, April 26, 2008 4:48 AM Subject: [Repeater-Builder] Cooling fan 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? Thank you, Doug - GM7SVK No virus found in this incoming message. Checked by AVG. Version: 7.5.524 / Virus Database: 269.23.4/1397 - Release Date: 4/25/2008 7:42 AM
Re: [Repeater-Builder] Cooling fan
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
Re: [Repeater-Builder] Cooling fan
I use the System 3 fan kit from Active Thermal Management: http://www.activethermal.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] [EMAIL PROTECTED] wrote: From: [EMAIL PROTECTED] [EMAIL PROTECTED] Subject: Re: [Repeater-Builder] Cooling fan To: Repeater-Builder@yahoogroups.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.yahoo.com/;_ylt=Ahu06i62sR8HDtDypao8Wcj9tAcJ
RE: [Repeater-Builder] Cooling fan
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@yahoogroups.com [mailto:[EMAIL PROTECTED] On Behalf Of TGundo 2003 Sent: Saturday, April 26, 2008 12:15 PM To: Repeater-Builder@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 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 [EMAIL PROTECTED] mailto:no6b%40no6b.com wrote: From: [EMAIL PROTECTED] mailto:no6b%40no6b.com [EMAIL PROTECTED] mailto:no6b%40no6b.com Subject: Re: [Repeater-Builder] Cooling fan To: Repeater-Builder@ mailto:Repeater-Builder%40yahoogroups.com yahoogroups.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 __ NOD32 2918 (20080303) Information __ This message was checked by NOD32 antivirus system. http://www.eset.com
RE: [Repeater-Builder] Cooling fan
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
Re: [Repeater-Builder] Cooling fan
Speaking of issues with fans, I recently had a GR-300 repeater that started emitting a howling sound when users transmitted. Thought it might be a temperature change issue until I got to the site and heard the same noise as soon as I opened the door. Turned out to be the fan in the rear housing somehow causing a microphonic condition in the transmit radio; I suspect a loose shield. The quick fix was to remove the fan from the radio housing and place it directly behind the housing. No more noise, still supplying air to cool the heat sink. Sometimes the little stuff can be very frustrating. Milt N3LTQ
Re: [Repeater-Builder] Cooling fan relay circuit?
The ELK-960 Delay Timer should fit rigth in, however no temperature sensing. http://www.elkproducts.com/products/elk-960.htm ---per LA9XKA At 05:05 17.05.2007, you wrote: My club has several ACC controllers and none have provided for cooling fan control. Does anyone have a simple circuit to turn on a fan with PTT and then keep it running for xx minutes after PTT is released? The repeater PTT line goes to ground on transmit. Most of the NE555 timer circuits that I have seen will not work in this configuration. Delay on drop out. DODO. Thanks de David K5RAV Yahoo! Groups Links
Re: [Repeater-Builder] Cooling fan relay circuit?
Hi Guys. I have used these in the past. This kit is from OZ but I am sure you must be able to get something similar over there. http://www.jaycarelectronics.com/productView.asp?ID=KC5381CATID=keywords=KC%25 Chow for now Brett Per Molund wrote: The ELK-960 Delay Timer should fit rigth in, however no temperature sensing. http://www.elkproducts.com/products/elk-960.htm http://www.elkproducts.com/products/elk-960.htm ---per LA9XKA At 05:05 17.05.2007, you wrote: My club has several ACC controllers and none have provided for cooling fan control. Does anyone have a simple circuit to turn on a fan with PTT and then keep it running for xx minutes after PTT is released? The repeater PTT line goes to ground on transmit. Most of the NE555 timer circuits that I have seen will not work in this configuration. Delay on drop out. DODO. Thanks de David K5RAV Yahoo! Groups Links
[Repeater-Builder] Cooling fan relay circuit?
My club has several ACC controllers and none have provided for cooling fan control. Does anyone have a simple circuit to turn on a fan with PTT and then keep it running for xx minutes after PTT is released? The repeater PTT line goes to ground on transmit. Most of the NE555 timer circuits that I have seen will not work in this configuration. Delay on drop out. DODO. Thanks de David K5RAV
RE: [Repeater-Builder] Cooling fan relay circuit?
David, It's not necessary to run the fan unless the radio gets hot. The most reliable and practical method of controlling a fan is also the simplest and cheapest: a snap-action thermo-switch mounted on a heatsink fin. I use a Cantherm switch from Digi-Key that starts the fan at about 120 degrees Fahrenheit. It's a good idea to select a DC-operated fan that is specified for low EMI, such as those made by Panasonic. Some DC fans generate a lot of conducted and radiated noise. 73, Eric Lemmon WB6FLY -Original Message- From: Repeater-Builder@yahoogroups.com [mailto:[EMAIL PROTECTED] On Behalf Of drwoolweaver Sent: Wednesday, May 16, 2007 8:05 PM To: Repeater-Builder@yahoogroups.com Subject: [Repeater-Builder] Cooling fan relay circuit? My club has several ACC controllers and none have provided for cooling fan control. Does anyone have a simple circuit to turn on a fan with PTT and then keep it running for xx minutes after PTT is released? The repeater PTT line goes to ground on transmit. Most of the NE555 timer circuits that I have seen will not work in this configuration. Delay on drop out. DODO. Thanks de David K5RAV
