Years ago - pre-POTA and pre-lithium - some intrepid QRPer (a W3-lander) decided to see how many states he could work with a single 9V alkaline battery during Sweepstakes. I don't remember his results but his radio was a new-at-the time Norcal 40A.
These days, any weekend POTA activation can serve as a test platform for this and other absurdities.
I decided to see if a 9V alkaline battery could power my TR-35 long enough to make the 10 contacts required for a valid POTA activation. The TR-35 draws 90-100 mA on receive. Transmit current (with 9V DC in) is 700mA and that results in an RF output of about 1 watt on 20m and 2.5 watts on 40m.
In all, I made 11 contacts and did a lot of CQing.This was on a Wednesday morning - more contacts and less CQing would be the likely result on a weekend.
The capacity of a Duracell 9V battery is a measly 300 mAH with a 50 mA load. The TR-35 draws twice this much current just on receive.
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| This cannot be correct |
No one mentioned any chirp on my signal but I'd be surprised if the radio was able to produce a steady tone.
Eleven contacts and about 40 minutes later, I QRT'ed and the battery's voltage popped back up to 8V. The meter also shows 13mAH used for the activation - this is not possible and shows that these meters don't accurately measure small amounts of current when toggled on and off briefly (ie, 22 wpm CW).
This was a fun experiment. I may repeat it sometime during a CW contest just to see how many QSO's can be squeezed out of a tiny battery.
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