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Author Topic: FT818 max power on stock internal battery  (Read 409 times)

M6EES

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FT818 max power on stock internal battery
« on: April 30, 2022, 01:08:39 PM »

I've seen one or two youtube videos suggesting that with the pwr icon flashing on the FT818 you are actually getting the full 6 watts on internal battery (not 2.5 watts).

This seems different to what the (confusing) manual says.

Has anybody tested this on a power meter ?
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GRUMPY2021

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Re: FT818 max power on stock internal battery
« Reply #1 on: April 30, 2022, 04:57:18 PM »

On internal battery you'll get a L with 2 bars blinking and that's as high of power you can get which is 2.5 watts.   When you go an external battery the L is blank and that means its on high power of 6 watts.   

Page 25 of the manual explains it all but it's something you really have to think about.  I agree the manual is a mosh pit.   
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WB0FDJ

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Re: FT818 max power on stock internal battery
« Reply #2 on: May 01, 2022, 09:37:32 AM »

FWIW What you are describing from the YouTube video is how my FT-817ND works.

When operating on the internal battery the processor automatically defaults to 2.5 watts output and I see the L with 3 smalls bars. In the menu when PWR is selected each push of the button steps power down in increments so from the 2.5 watt setting you go to 1.0 watts (the L with 2 bars), 0.5 watts (the L with 1 bar) and then another push goes to 5 watts and you see the L with 3 bars flashing. I get 5 watts out in this setting but given the battery capacity I never use this. The FT-817 manual is much more clear on this than the FT-818 manual (which doesn't explain anything...)

WB0FDJ Doc 73
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M6EES

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Re: FT818 max power on stock internal battery
« Reply #3 on: May 02, 2022, 01:13:38 AM »

FWIW What you are describing from the YouTube video is how my FT-817ND works.

When operating on the internal battery the processor automatically defaults to 2.5 watts output and I see the L with 3 smalls bars. In the menu when PWR is selected each push of the button steps power down in increments so from the 2.5 watt setting you go to 1.0 watts (the L with 2 bars), 0.5 watts (the L with 1 bar) and then another push goes to 5 watts and you see the L with 3 bars flashing. I get 5 watts out in this setting but given the battery capacity I never use this. The FT-817 manual is much more clear on this than the FT-818 manual (which doesn't explain anything...)

WB0FDJ Doc 73

Good point - I just looked up that section in the FT817 manual online and it is much clearer. The FT818 manual seems completely different.

Would be good if an 818 owner could test 6 watts out on internal battery with a power meter.
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WA3SKN

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Re: FT818 max power on stock internal battery
« Reply #4 on: May 05, 2022, 02:25:27 PM »

More important... how long can you talk at 6 watts vs 2.5 watts with the internal battery?
And how much heat is generated?
Then start planning on a small external battery for longer operations!  How small?... whatever you are willing to carry!

-Mike.
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IW5CWC

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Re: FT818 max power on stock internal battery
« Reply #5 on: May 31, 2022, 02:13:10 AM »

I have a FT-818 too and would be glad to take the measurement.
But I miss a power meter... ???
Do you have a simple schematic or kit to suggest for QRP power measurement? It is something I already thought about, but not yet realized. This could be the right time to do.
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KG6BRG

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Re: FT818 max power on stock internal battery
« Reply #6 on: June 24, 2022, 12:19:13 PM »

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AE0Q

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Re: FT818 max power on stock internal battery
« Reply #7 on: June 27, 2022, 07:18:58 AM »

Do you have a simple schematic or kit to suggest for QRP power measurement? It is something I already thought about, but not yet realized. This could be the right time to do.

It is easy to build a circuit that lets you measure RF power with a DMM.  It is about half way down on this page:

https://www.ab4oj.com/test/pwrmeas.html

Glenn AE0Q
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KB1GMX

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Re: FT818 max power on stock internal battery
« Reply #8 on: June 29, 2022, 06:14:06 PM »

Its very similar to the FT817, at full power the internal battery
does not last long forcing lower power.  Its just not a big enough
battery to supply the demands for any reasonable time.  Why?  Its
what they had space for.

If you feel full power is desired get a Bioennio or other LIFePo4
at about 10ah and put it in your pocket (lighter and smaller then
gelled lead acid)and you will be able to run for many hours and
get full power.

The internal battery has limited lifetime even for RX only.  Any
TX even at 2W eats into that battery life greatly.

I own a Ft817 and got the chance to use the FT818.  basically
the same and 818 draws a tiny bit more power on TX.

Allison
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IW5CWC

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Re: FT818 max power on stock internal battery
« Reply #9 on: July 03, 2022, 09:01:34 AM »

I use my FT-818 either with internal battery or with 3S LiPO battery.
I noticed that the input voltage threshold under which low power is automatically selected is 11V.
However, one can still operate the pwr set button to restore whatever power he wants. After one year since I started operating the FT-818 (and no measurement so far, this is my fault!) I am not sure if it is possible to have the max power emitted even with input voltage lower than 11V (including internal battery) or not. In the former case the blinking low power icons should be intended just as a warning that your battery won't las for a long time...
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IW5CWC

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Re: FT818 max power on stock internal battery
« Reply #10 on: July 03, 2022, 09:51:18 AM »

I made some output measurements and posted them here.
https://forums.qrz.com/index.php?threads/power-measurements-on-a-yaesu-ft-818nd.817391/

Sorry I didn't check your measurement before writing my post just above.
You confirmed that at least in VHF it is possible to output 5W with internal battery while the low power LCD icon is blinking. Great! For my operations internal battery lasts around couple of hours in 5W power, which is often enough for a portable session.
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