That is exactly my very same conclusion after having tried a few activations with a MTR-2B.
I prefer million, gazillion times my trusty FT-817ND with all bands and modes in a compact package.
The MTR is fine for the minimalists, but I’m definitely not one.
73,
Guru
Hi Simon,
There is an FT817 group at Groups.io, in fact some of the folk here are not only members but are moderators and an owner.
That info would probably be of great interest to some of the folk over there.
If you aren’t already a member I suggest joining up and posting that info.
Some time back one of the members there analysed the current consumption of the 817, even to the extent of saying that using the rear antenna connector costs more in current due to the relay that is pulled in when using that connector. Only 20ma or so, but still,…
I think you are right about the heat sink, it is most likely only the area around the final stage that is providing that function. The rest does provide anti-twisting stability so it protects the PCBs from damage.
Ditching the NiMH in favour of Lithium based cells is a great idea. In fact operating the whole rig from solar cells embedded in your shirt and backpack would remove the need for any battery. the 817 requires 400ma+ on rx alone so that is some way off yet. 
73 Andrew VK1DA/VK2UH
I can’t follow that reasonng. The chassis is good at conducting heat, the area around the final stage will be warm because the heat is being conducted away to the rest of the chassis. Remove all the metal except for the warm area of the chassis and that warm area would become hot, perhaps dangerously so for the components.
I find the ft817 very light. my first HF sota i carried a TS-480 and a 12AH lead battery! so a life-po4 battery and a ft817 is very light i find 
Not really. The lithium batteries are 3.7 V instead of 1.25 V, so compare Watt-hours instead of mA-hours. That makes it 12.2 Wh vs 3.2 Wh.
If you aren’t recharging them, the non-rechargeable lithium AA batteries are half the weight of NiMH batteries and 1.5 V at 3000 mAh (4.5 Wh).
wunder
I walked the Cape Wrath trail a couple of times over the past decade. Since it requires carrying up to a week of rations for the first half, my daily ration was a defeated meal for dinner, pepparami for lunch, and most of the rest of the calories each day from a large pack of shortbread (the fat content means this has a greater calorie to weight ratio than chocolate). I was a little unwell after I finished, which I attributed to the poor diet, I no longer find shortbread appetising.
Since then, I still use dehydrated food for dinner, and I quite like them, but I supplement with dried fruit, nuts and other stuff.
Long distance walks in the north of England are much more pleasurable than north Scotland as you can be guaranteed if a pub meal at least every couple of days. Also the midges in Scotland mean that cooking a good meal outside your tent is a chore.
About a year ago I bought a job lot of around 40 packs of adventure foods “pasta a la funghi” dehydrated food. That too was a mistake…I am now utterly sick of that variety.
I gave weights for the whole pack, not 1 cell. Since the radio is basically constant-current, it is mAh that counts not Wh. 3xLiIon has the same EOL voltage as NiMHs. More voltage really doesn’t help much. Unless you put in an SMPS. If you run the rx 6V off an smps, you could almost double the rx time from Li batts. It would be a big improvement, as the rx current is a real issue on a long trip e.g 16 days=8-16hrs rx time.
Good idea. I had overlooked L91s. Maybe the best choice for special trip use like this. 120g pack weight, 9.6V EOL. >11V over most of the discharge. And they fit in the battery hole. I can actually get them before I go. And no BMS or charging. ($1.2/Wh)
BTW, Another option to increase capacity with rechargeables is to float from a LiSOCL primary cell with a tiny boost convertor. A D size is 0.7Wh/g ($0.46/Wh) vs 0.28 for L91s. The catch: this is at 20mA. Note that D alkalines are not too shabby at 25mA: 0.17Wh/g $0.2/Wh
more than happy to relieve you of any (less than a decade old 
) shortbread.
True 
Variety is the spice of life. I did 2 submarine patrols where the spuds (several tons) went off:
Yes the reasoning is faulty. I should have put it that even with reduced heat sinking of a slimmer chassis, there is probably enough remaining to do the job several times over.
The real question is what is the thermal resistance of the standard frame/chassis and how much would its heatsinking be compromised if some mass was taken away from the other end of the chassis? The answer to that is probably that it is the surface area of the frame that contributes the thermal resistance. So avoid reducing the surface area, which you would anyway as you don’t want the rig to break apart when you tune the dial or change bands.
And how much heat actually needs to be dissipated? The worst case is FM where the input power to the final amp is in the region of 10 watts and output is 5 when on the highest power setting, leaving ~5 watts to be dissipated. (The power dissipation of the tx cycle is highest on FM so don’t use FM if you want long life from your battery charge. Running lower power levels would reduce battery consumption very slightly. It doesn’t halve when you run half power, but at 0.5w the battery life does improve. )
Average power in ssb without compression is in the low 20-30% area, so overall the power to be dissipated is about 1 watt for SSB added to the base power requirement due to the class B bias current. Say 2 watts. I think that one half of that chassis can dissipate much more than 2 watts. A small heatsink about 2cm x 2cm can do that, with fins. So from the back of my envelope, I think the heat sink requirements would be adequately met by half the chassis.
But wait - that only considers the final amplifier stage. The regulators and the audio output stage also generate heat, and every component on the board contributes a bit. As mentioned a few days ago, the rig does run fairly hot.
Most of us just change the batteries, use different modes, or QRT when we have 4 contacts. Reengineering the radio to make it lighter is an interesting experiment but not many of us would ever consider it.
Andrew VK1DA/VK2UH
Carbon fiber covers won’t provide any RF shielding. That is unlikely to be a problem on a summit, but might be noisy in town. A layer of foil would probably fix that. Also, you could decide no to care about it.
wunder
It wouldn’t surprise me to find that modern dehydrated food is a lot better than the stuff that was available forty-odd years ago!
I like the solid feel of the 818…it gives me confidence in the radio as being suitable for field use. And by field use I mean field use…not under a marquee at a club field day.
The small screen, annoying menu system, and cramped front panel all suggest that focus is on field operations, with everything else a compromise.
Cutting off parts of the radio, or replacing the covers with plastic just seems to go against the whole ethos of the 818.
Having said that, I totally understand the ultralight philosophy, but I prefer saving weight by using a coke can as a meths stove, so that the 818 can remain intact.
I would say though, it was surprised to find it weighs a kilo. Given the weight it is a shame Yaesu couldn’t upgrade it to 10 to 20W when they changed the model number from 817 to 818.
Foil is an obvious part of the layup, and since you are vacuum bagging into an external mould, the foil is a glue stop layer.
The 817 has quite a bit of spurii if you put the antenna wire right close to the case, so I will be trying to shield it against what is leaking out, not leaking in.
50um AL foil is only 1 skin depth at 3MHz. There is also nickel shielding spray, or copper shielding tape. Guess we will find out if foil is sufficient.
So my FT817 with batts, and without microphone is now 710g.
Covers 70g, probably 40g if made properly from carbon. made from fglass cast (broken arms) + some carbon as it was what I had on hand.
One thing I noticed is that the finals heatsink pedestal is not machined, and is not very flat, leading to a thick layer of grease. Not very good.
Well spotted Andrew
Although I inherited the group after I migrated it from yahoo groups to groups.io so don’t know if there has been a weight breakdown of the FT-817 in the past I don’t ever recall seeing one so you are spot on there Andrew.
Mark.
First, as many have said before on this reflector, there is no perfect rig and we all have differing needs, so I agree with most of what’s been said so far [esp. Brian’s @G8ADD comment about taking the radio that gives you pleasure].
Those who build miniature radios in tobacco tins are having fun with a technical challenge, no doubt, but as an argument for portable-ops weight/volume reduction it’s a red herring - the Law of Diminishing Returns.
And while I agree that losing my excess body fat would mean, in principle, that I could carry extra kilos in equipment, it’s a young man’s argument. At my age [nearly 70], no matter how fit you are, it’s sensible to carry the lightest pack practical for the sake of one’s arthritic [or soon-to-be arthritic] joints.
I am lucky enough to have a number of portable rigs which I mix and match to suit different activations. Unless I want to do VHF SSB [sadly a minority sport nowadays] I prefer to take my Yaesu FT1D and KX2 rather than my trusty 19-year-old FT817, a configuration that gives me redundancy as well as better performance & functionality for about the same weight and volume.
The new case was worth the trouble, but milling and fettling the chassis really wasn’t.
I removed the weight in the microphone, and replaced the curly cord with a 0.5m flat ethernet cable (cut down from the router at home). 170g->107g.
Until you pass an activator coming down the hill and see they are 10 years older than you, carrying half as much weight and having way more fun.
My entire SOTA rig comes in at 812g. I use a small bottle of water as a throw weight and it goes down the hatch after serving it’s purpose so I don’t count it in the total weight.
My back and knees could definitely tell a different once I learned CW and picked up an MTR3b and built an EFHW. I tried taking the FT818 up to a summit with a picnic table to play SSB a few months ago and there was a marked difference in the way my pack felt!
If you want the FT817/818 to feel featherlight, pack a 30KG-ish Rucksack then strap a PRC-320 under the top flap and cram a couple of spare clansman batteries (about 3.5kg each iirc) into the pack, then pick up a rifle and you’re ready to go hiking 
Do a couple of summits like that and every one afterwards will feel effortless 
