24V-12V Voltage Reducers and HAM Radios

[canucksafari]

Well, it is time to go out and buy a voltage reducer. My truck is 24V. Now if it was just for a CD player and other electrics, I wouldn't worry so much. However, from what I have heard, some voltage reducers can cause problems for HAM radios.
I am doing a HAM course right now and spoke with the instructor. He confirmed that certain reducers can have a square wave pattern on the out put which would affect the HAM radio.
Is this true? If so, which voltage reducer can people recommend. I am thinking one which can handle a constant 20 amps will be enough.

[FJ40_owner]

Originally Posted by canucksafari

Well, it is time to go out and buy a voltage reducer. My truck is 24V. Now if it was just for a CD player and other electrics, I wouldn't worry so much. However, from what I have heard, some voltage reducers can cause problems for HAM radios.
I am doing a HAM course right now and spoke with the instructor. He confirmed that certain reducers can have a square wave pattern on the out put which would affect the HAM radio.
Is this true? If so, which voltage reducer can people recommend. I am thinking one which can handle a constant 20 amps will be enough.

A good 24 to 12 converter will be pricey. I have one that retails for $700. I bought it used on ebay for 100 something.

Try these guys.

24 volt to 12 volt DC/DC converters (fully regulated) from 100 to 700 Watts non-isolated and isolated.

[Pin_Head]

Switching type power converters have a high enough frequency that the ripple in the output should not cause any noticable interference. The ripple in the ones in the link above are 50 mV @ 25 kHz. If this did cause a problem you could filter out this ripple with a 12V motorcycle battery. A battery would also let you get away with using a smaller power supply as most tranceivers only use the max power during the transmit cycle and use very little power in receive mode.

If you are running a typical 5W hand held transciever, the power use is insignificant for most converters as it would use about 0.5 amp @ 12V.

[canucksafari]

Thanks for the info guys. I will hopefully have a transmitter which will do a max 20 watt transmit. The third battery is a good idea. Now I just have to find a space to fit it.

As a side topic, has anyone seen these old military surplus reducers which are basically a long coil wrapped on a cermic insulator. The voltage is adjusted by moving the centre ring. This is what they use to use on the NATO spec trucks to run their 12 V tube radios. My neighbour had one he used on his 3B swapped tray-back to run his stereo and CB radio. They work fine as long as the load does not change. If you change the load then you have to adjust it again to get the correct voltage. Apparently they also get very hot.

[Flyingdog5000]

Originally Posted by canucksafari

Well, it is time to go out and buy a voltage reducer. My truck is 24V. Now if it was just for a CD player and other electrics, I wouldn't worry so much. However, from what I have heard, some voltage reducers can cause problems for HAM radios.
I am doing a HAM course right now and spoke with the instructor. He confirmed that certain reducers can have a square wave pattern on the out put which would affect the HAM radio.
Is this true? If so, which voltage reducer can people recommend. I am thinking one which can handle a constant 20 amps will be enough.

Does you truck use a single 24v battery, or do you have two 12v batteries running in series (connected end to end)? On the off chance that you do, so you can connect your power leads to the + and - poles of one battery and get 12 v without the use of a step down transformer.

Flyingdog (W8PM)

[canucksafari]

Originally Posted by Flyingdog5000

Does you truck use a single 24v battery, or do you have two 12v batteries running in series (connected end to end)? On the off chance that you do, so you can connect your power leads to the + and - poles of one battery and get 12 v without the use of a step down transformer.

Flyingdog (W8PM)

It is a dual 12V batteries in series producing 24V. You can not tap off one battery without a battery balancer, otherwise it will over charge and cook the battery which is not being tapped. I'll see what Greg at G&S Cruisers is selling their battery balance for. It would save me the cost of a third battery.