True about 3 db but not really on battery life. Power usage is not linear in that the efficiency drops as you reduce power on a 100 watt rig so savings are not as big as you think. Also a 100 watt rig at 5 watts out draws a lot more power than a true QRP rig. So if you want minimal weight to carry and good battery life a rig like a KX3 makes a lot of sense. Better rig than 817.
FWIW, here's some data from an FT897D I had several years ago. For a given band (20 meters shown), current draw vs power is nonlinear as you say. Additionally, the current draw at max power is not the same on all bands.
Just a note to say I worked the 857 /p for the first time last night and honestly don't know how I would improve it. Rugged build, pulls the signals in, easy to pack up and carry etc. Runs just dandy off 12v also. Sure it's no big rig and the DSP filtering is basic but for what it's designed to do it does perfectly. Wouldn't dare take say a 991 properly /p, maybe run it from the back of a car but wouldn't want to take it up hill and down dale-looks too fragile for that. No such worries with the 857.
As a keen hiker and nature lover I have accumulated quite a few radios suitable for portable use over the years. These include radios like the Icom IC-706 and IC-7000 series, Yaesu FT-817, 857, 850 and 897, Elecraft KX3 and a few smaller rigs. The KX3 is a great radio, but it is quite expensive by the time you have added a few options. The deal breaker for me on the KX3 is the sound, I am sorry many won't agree but after a few hours of listening the "white noise" coming from that radio I get really tired and operating is no longer a pleasure. The 857/897 sounds better, but their RX's are not as good (selectivity/dynamic range) as the KX3, but that would only matter if you work CW and want to do some CW contesting. Operating from a remote lodge with the FT-897, digital modes as well. And the great little FT-857D, even after being on the market for so long in a class of it's own. I love the 817, but it is limited to 5W unless you add an external amp. For true portable/backpack work in the wild it is still my weapon of choice. Portable with the 817 in the forest. The Icoms are not so great, noisy receivers, bad receivers (I am primary a CW operator) and quite power hungry. But there is a new player in town, and by far my favorite at the moment, the FT-991, a great RX, great sound, good price if you consider you get all bands, 100w and tuner included. It is slightly smaller than a 897 with FC-30 tuner. It is quiet happy with voltages as low as 11.6V (The lowest I have tested). It might look fragile but the construction is solid and I have no problem taking it to the bush. Comparing the FT-991 to the FT-897. But any radio is better than no radio! 73, Rudi de ZS6DX/V51VE
I have used a FT991 some and I was NOT impressed with receiver audio at all. Sounded pretty flat and boring and it was not rig settings either.
Strange, every owner I have spoken too loves the audio........ And if you only used it "some" you have used it a lot less than me! It is a complex radio, lots that can be adjusted and MISS adjusted
I am not technically challenged when it comes to radios and I played 991 side by side with other rigs and it stands out lacking a lot in sound and selectivity on HF. Never tried it on 2m or 440 so cannot comment there. If you have nothing to compare it with you might like it but I was very disappointed with it. I was not alone in my evaluation that day either.
Having owned a K3, you are correct on long term exposure to the receive audio. One reason many as well as myself, with other reasons) I moved it to a back up radio position, and then completely out of the shack. An expensive "back up" radio. Having played for some time with the 991, at a far lower price, I found myself really enjoying it. Don't own it yet, but may in the near future. I think for the $$, it would be a great portable radio as would the IC-7200 (if you have a resonant antenna and don't need/want 2 meters and up).
12 volt battery power is a bit of a misnomer. Automobile electric circuits are commonly referred to as 12 volt circuits when they can vary in voltage from 11.8 to 14.1 volts and still be in spec. Radios that are designed for mobile use will work in that range. For the money, I think a used FT-897D is the bee's knees. There's one in my shack. I keep an ancient FT-100D for HF work in the truck, aside from finals that are difficult to find replacements for if damaged the FT-100D is also a good rig. But I must admit a bias towards Yaesu.
