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Author Topic: QRP voltage booster  (Read 777 times)
AD5VM
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Posts: 26




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« on: June 22, 2013, 01:11:09 PM »

Elmers,
   It seems many QRP radios and kits, which are designed to be operated in spartan conditions and powered by a small battery, are still designed to operate at full power when the supply is 13.8V.

I have an MFJ-Super battery booster to use with my IC-7000 and it works great as long as you use the RF sense feature, but I was wondering about something much smaller. For $12 this can be purchased on amazon:

http://www.amazon.com/3-5-30V-4-0-30V-Booster-Converter-Regulator/dp/B008FLE7PA/ref=sr_1_1?ie=UTF8&qid=1371930970&sr=8-1&keywords=voltage+booster

It is good for 3 amps continuous or 5 amps for shorter duty cycles. Does anyone see a problem with using something like this for a five or ten watt radio?

Thank you very much,
-Larry
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W8JX
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Posts: 5904




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« Reply #1 on: June 22, 2013, 01:23:51 PM »

Bad idea, you will not see any measurable difference in down range signal and you will see a decrease in battery life due to higher drain to create a higher voltage and power lost in conversion.
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KG4RUL
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« Reply #2 on: June 22, 2013, 01:25:20 PM »

Also, there is a high potential for the device to generate noise.
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AF6WL
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Posts: 142




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« Reply #3 on: June 22, 2013, 02:24:44 PM »

Potentially noisy, but it could be useful it you are looking for extra headroom when charging an internal battery from an external 5V...12V source.
(e.g. the KX3 manual says >13.8V for charging the internal 9.6V pack.)
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W9IQ
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Posts: 102




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« Reply #4 on: June 23, 2013, 05:28:05 AM »

Larry,

I too would be concerned about switching noise from the device you referenced. But given the price, it may be an inexpensive experiment as long as you provide over voltage protection.

Generally, one spends more time receiving than transmitting. It would seem that this type of booster would waste a great deal of your battery power since the full 12-13 volts will not provide better receiver performance. In many radios, this goes up as heat.

I would check the schematic to see what happens in the power rail of the transceiver in both the transmit and receive modes.

- Glenn W9IQ
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K8AXW
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Posts: 3861




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« Reply #5 on: June 23, 2013, 07:06:15 AM »

I agree with IQ that this would be a cool experiment, especially since it costs only $12 + shipping.

However, the power output of your QRP transceiver could be measured at various voltage levels by simply lowering an AC powered supply to simulate lower battery voltages.  RX performance could also be evaluated at the same time. 

If it's then determined that a booster circuit would be beneficial then the module could be bought and evaluated for noise and performance.

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