Many thanks to Jens (DJ2GMS) who recently reached out to share results from some very simple tests he performed on the Icom IC-705 and Yaesu FT-818. Jens writes:
A comparison of the Yaesu FT-818 and the Icom IC-705 (no comments, just facts):
On ext. 10,1V the FT-818 only needs 32 mA more than the IC-705
IC-705 (342 mA):
FT-818 (374 mA):
Min ext. voltage for TX of the IC-705 is 10,1V (appr. 1,8 Watts)
With 10,1V the FT-818 delivers 5 Watts
Minimum ext. voltage for TX of the FT-818 is 8V (appr. 3,5 Watts)
Thanks for sharing this, Jens!
Interesting.
Which power-consuming options were enabled in the 705? Wifi? GPS? Bluetooth? Backlight at which percentage?
73
Ekki
Hi,
everything was switched off. No Auto adjustment for the bachlight but set fixed to 30%.
Interesting was the first word I thought, too!
Clean, simple, basic data, just the way I like it.
The most interesting was the 818’s transmit performance at 10.1 volts; a full 5 watts out is a nice feature for battery operation.
Thank you Jens, and Tom!
I’ve still have and use an older 817nd.
I bought it brand new when it first came out many years ago. It’s an excellent rig for its time and is still a very good portable radio. It’s never seen a repair shop in all the years I’ve had it.
The newer radios have a lot more features but for running a portable QRP setup they are very hard to beat…
In my humble opinion
73 Greg
The FT817 has a relay for selecting the front and rear antenna connectors.
When rear is selected the relay is energized drawing slightly more current. This is not a latching relay, but is energized at all times the rear connector is selected.
This would make the rig draw more current using rear antenna connector. How much more, I am not sure.
The IC705 current draw.
at 14.5V to 13.0V 10.8W out 1.9A, 11.0V 5.4W 1.5A
73, ron, n9ee
Hi,
of course the front connector was used during my tests ?
Jens
The 817/818 contains a pile of relays for band pass filters, etc. power consumption is all over the place for several reasons depending on what you’re doing, and even what band.
From an engineering standpoint this comparison is VERY interesting to me because they are so close: a 20+ year old radio design has nearly the same power req as a very modern SDR likely using parts fabbed on teen-nanometer processes and maybe even GaN or GaAs (III-V semi) in some RF stages.
The higher voltage for the final amp is practically-trademark Icom, who’s notorious for making radios that can’t handle low voltage. This is even funnier when you consider the internal digital circuits (probably some analog too) run at 3.3V like cell phones, maybe even lower still, unless they spec’d some really old parts.
A simple but useful check. I will operate my 818 mobile with a solar panel only (not any external batteries) and a variabile voltage regulator made with LM338K, I will keep the voltage at a good 11 – 12 volt, obtaining the max RF power, with a good IN-OUT differential for a good work of LM338K.
TNX for the article