FT817 - 5w with AA Battery Tray? - QRP Forum at eHam.net

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eHam.net Forum : QRP : FT817 - 5w with AA Battery Tray?

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FT817 - 5w with AA Battery Tray?	Reply
by K1WJ on October 17, 2009	Mail this to a friend!
Anyone run 5w with AA battery tray? I know radio defaults to 2.5W. Results on 5w with AA tray? 5w acheived? How long can Xmit before AA will not support 5w output? Thinking of buying a FT817ND. Thanks to all.....David K1WJ

RE: FT817 - 5w with AA Battery Tray?	Reply
by W3JJH on October 17, 2009	Mail this to a friend!
8 carbon-zinc batteries will deliver 12 V for a few minutes of 5 W operation. 8 alkaline or NiMH batteries will deliver 9.6 V for quite a bit longer, but won't provide enough potential for 5 W out. That's the reason for the automatic default away from the high power setting.

RE: FT817 - 5w with AA Battery Tray?	Reply
by K1WJ on October 18, 2009	Mail this to a friend!
W3JJH: Thanks, that is all I really need to know. 73 K!WJ Dave

RE: FT817 - 5w with AA Battery Tray?	Reply
by WB6BYU on October 18, 2009	Mail this to a friend!
You MIGHT be able to get 5W output if you used Lithium AA cells, which would provide full output voltage with lower internal resistance and higher capacity than alkaline cells. But given the short operating time of the AA cells, you're probably still better off running them at 2.5W.

RE: FT817 - 5w with AA Battery Tray?	Reply
by AA4PB on October 18, 2009	Mail this to a friend!
In addition to AH capacity, which determines how long the radio will run, you have to be concerned with peak current capacity. The AA batteries (depending on the type) may not be able to supply the peak current requirements at 5W output.

RE: FT817 - 5w with AA Battery Tray?	Reply
by K0RGR on November 11, 2009	Mail this to a friend!
I use a small external gel cell battery with my 817 for extended operation at 5 w.

RE: FT817 - 5w with AA Battery Tray?	Reply
by VE3WMB on November 12, 2009	Mail this to a friend!
Keep in mind that 2.5W is only a half S-unit down from 5W. If you really need to run 5W then use an external Gel cell rated at something like 3 to 5Ah. Unfortunately the Ft-817 is not optimized for power consumption and it is a bit of a hog as compared to other similar sized QRP rigs. AA cells are rated for maximum current draw and if you look closely most of the battery manufacturers do have the technical specs for their batteries available on the web. Drawing too much current even for a short time will kill most of the AA Alkalines quite quickly. NiMH and Lithium cells are better suited to deliver higher currents. I suggest reading KA7OEI's page on FT-817 power consumption : http://www.ka7oei.com/ft817_pwr.html Most noteworthy is using the front BNC connector rather than the rear SO-239 for your antenna when operating from battery ... this saves almost 30mA of drain on RX which is quite significant.

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