1. You can now help support WorldwideDX when you shop on Amazon at no additional cost to you! Simply follow this Shop on Amazon link first and a portion of any purchase is sent to WorldwideDX to help with site costs.
    Dismiss Notice
Dismiss Notice
This forum does not allow a single user to have more than one username. If anyone wants to change their username contact an admin and it will be done. Multiple accounts belonging to the same member will be deleted without warning.

fan kit on magnum omegaforce s45hp

Discussion in 'Home Brew' started by Se7en, Jul 5, 2011.

  1. Se7en

    Se7en Well-Known Member

    Joined:
    Jun 27, 2010
    Messages:
    4,576
    Likes Received:
    210
    wheres a good place to hook up the fan? i dont want to tap it inline cause the power wire is a constant. i was thinking on the on off volume switch..... but that is hard to get to i think.... let me know? thanks.


     

  2. VA3ES

    VA3ES Old Buzzard

    Joined:
    Oct 30, 2010
    Messages:
    645
    Likes Received:
    77
    Interesting mod. I believe the radio uses a TX relay. I would wire it to that, so that the fan only comes on in transmit, and I would add some kind of time delay so the fan keeps going for about 30 seconds after you unkey.
     
  3. Wire Weasel

    Wire Weasel Senior Moment

    Joined:
    Dec 13, 2008
    Messages:
    2,779
    Likes Received:
    372
    Tap into the 12V line going to the radio. Add a switch in the line for on/off. Add a potentiometer in line to vary the speed. 100ohm if you can find one but a 250ohm is more common and will work. A 12V muffin fan running on 14/15 volts (running engine) will run very fast and make too much noise. Slow it down with the pot adjustment.
     
  4. Superidgit

    Superidgit Active Member

    Joined:
    May 24, 2011
    Messages:
    412
    Likes Received:
    5
    I dont know if this would be practical for your application but it may be worth a look 12Vdc Thermostat KIT, 5 to +30°C (MK138)
     
  5. you could also just power the fan off the vehicles fuse box so that its only on when the vehicles key is in and turned .
     
  6. Wire Weasel

    Wire Weasel Senior Moment

    Joined:
    Dec 13, 2008
    Messages:
    2,779
    Likes Received:
    372
    Additional cooling fans are a great idea and many times necessary on certain items. High power devices like Export radios and transistor amps may come with heat sinks but we see that they can still run uncomfortably hot and we want to protect the finals.

    Easy enough to add say a 4 inch muffin fan to the equation and I do this all the time and have such fans running on my gear now. Problem is that a 12V fan running on a hot power source like a home station power supply that the radio is running on (typically turned up somewhere between 13.8-15 volts) or a running vehicle engine (again operating between 14-15 volts) will make a 12V rated muffin fan run very fast and typically will be very noisy.

    Experience shows that you can slow down these simple shaded pole 12VDC fans to around 9.5-10.5 volts and they will run plenty fast enough to do the cooling job and be much quieter, even to making little to no noticeable noise. And the extra cooling is not needed all the time - only when doing extended transmitting.

    So it works out to make the fan operation switchable - turn on only when needed. And provide a way to slow the fan down for lower noise making.

    On my base I have an extra small-amperage variable power supply that I run the fans on. Simply dial the voltage down with the knob to achieve the desired fan running speed.

    Mobile I have added a small toggle switch and a 250ohm pot in line with the fan and turn it on when needed and have the pot set to my desired run speed and it needs no further adjustment. Turn the fan on/off as needed. I also added an LED in line to remind me that the fan was running so I would be sure to notice it and to turn the fan off when no longer needed or getting out of the vehicle.


    Good luck
     
  7. Se7en

    Se7en Well-Known Member

    Joined:
    Jun 27, 2010
    Messages:
    4,576
    Likes Received:
    210
    thanks guy. but (24Vdc/ac) is not going to work. im going to hook it to inside so it turns on when the radio comes on. my rfx gets warm even when not transmitting.
     
  8. TonyV225

    TonyV225 W9WDX Amateur Radio Club Member

    Joined:
    Apr 18, 2005
    Messages:
    5,824
    Likes Received:
    306
    Buy a small fan and a cig lighter adapter wire it up and when needed plug the adapter in simple and easily moved from one vehicle to another. I could get into hard wiring the fan to a specific radio but why not be simple cost efficiant and make reusable in the simple method I have stated ;)
     
  9. Superidgit

    Superidgit Active Member

    Joined:
    May 24, 2011
    Messages:
    412
    Likes Received:
    5
  10. Se7en

    Se7en Well-Known Member

    Joined:
    Jun 27, 2010
    Messages:
    4,576
    Likes Received:
    210
    thanks.

    yea this radio is base use not mobile. thanks (y)
     

Share This Page

  • About Us

    The WorldwideDX Radio Forum was originally established in 2001. We pride ourselves on welcoming Radio Hobby enthusiasts of all types, while offering unbiased, informative, and friendly discussion among the members. We are working every day to make sure our community is the best Radio Hobbyist's site.
  • Like us on Facebook

  • Premium VIP Member

    The management works very hard to make sure the community is running the best software, best designs, and all the other bells and whistles. Care to buy us a beer? We'd really appreciate it!

    Donate to us!