Ham Radio - Cooling the Yaesu FT-817 for digital modes

A simple trick to keeping the FT-817 cool while running 100% duty cycle modes like JT65, PSK31 etc. You can get away with 5 Watts safely. The finals should be ok with the duration. They are 2SK2975 MOSFETs. From the spec sheet, they are rated at 10W dissipation when mounted to a heat sink.
Obviously you still need to be careful. Back to back digital QSO's in a contest could still heat it up over time. If you burn it for an hour straight and blow your finals, don't complain to me! (wink).

[@tanglewoood]

Thanks for the inspiration to cool my FT818 during FT8 transmissions. I went a different route by rigging a 12 VDC 3" (80mm) muffin fan on a wooden stand. The fan is aimed directly at the back of the radio. The fan is powered by the same PS as my radio. Good so far.

[@bill-2018]

I did a similar thing earlier this year. I have the FT817ND which I bought about two years ago and on F.M. noticed the heat sink got pretty warm on a long transmission. I'm a believer in keeping transistors as cool as possible so I cut a heat sink down and filed one corner to fit over the GND raised lettering and fixed it to the rig using the ground lug screw and used heat sink compound. This puts it closer to the transistors. Bill, G4GHB.

[@VA3OSO]

Good topic! The FT817 does get hot when transmitting on digital modes. I found a trick where if I used 10-11v power (3s lithium) even running JT65, the temperatures were much less and there was still the same amount of output power.

[@loughkb]

Yep, I remember reading about that a few years ago. Less power has to be 'eaten' by the finals at the lower supply voltage. Even then, and at 2.5 watts, it gets pretty warm back there. I've always been of the mind set that the cooler you keep components, the longer they'll last. I run most of my digital stuff at 2.5 watts, and with the added heat sink it hardly gets warm enough to feel now.

[@kevinj8258]

La Madriguera there is a kit that regulates power to the 817 to below 10v as any higher voltage is converted to heat. Placed an order for the kit but have not seen it yet. Not sure the guy making this is still in business.

[@WI9LL]

Great idea. I could picture one made specifically for this unit permanently installed with thermal grease and the works.

[@placeholder-065]

Hello Kevin, today got my cooling element delivered and tried it out on my 818ND. I ran 6 consecutive minutes in FT8 every 15" and 4 consecutive minutes in CW (CQ) at 22 WPM every 30" both modes at 5W out, the result is amazing ! The 818ND feels but a little - I repeat a little - warmer than it was when I switched it on. The solution is simple and very effective. Great idea, thank you. 73, good DX Gust ON6KE

[@richardnday]

Great idea. You could also take one of the old computer fans to cool your heat sink. Then, 5 watts without a wait.

[@loughkb]

+Richard Day it stays plenty cool with just the heat sink. Doesn't get warm to the touch.

[@dalemyers5096]

if it works ride with it. but id make mine more permanent. a small scew holding it to the radio, would fill that bill. for storage in travel unscrew it, packing it away in a thick felt bag with draw strings. to not damage the fins when in storage get that dense foam packing board, like that ships with heavy electronics. stuffing it onto the heat sink. if your using styrofoam. spray lightly some weak solvent and dab the foam to it. letting the heat sink, sink into the foam. but not to the land at the botom of the fins. this will eleminate or greatly reduce breakage or binding of the fins. to clean off residual gunk from the heat sink. spray carb cleaner on the heat sink. it will wash it off cleanly. you could even add a mini solar panel and a mini mufin fan, for force air flow. to mount mufin fans on heat sinks i use small dryway anchors they fill the space between fins and affix fans snug enough to work well.

[@MoTown44240]

Great tip.

[@sparky42]

Thanks , good idea . aesthetically a bit clumsy looking BUT better than blown finals for sure . I also have a nice small little 12 volt whisper fan I pulled from an old computer sitting right on top of my 817ND ( one of my 817 ND 'S , I love these little rigs ) it is sitting right over my finals and the fan alone really helps .. Best 73 de ka3fad

[@loughkb]

The finals in the 817 are actually rated for 10 watts dissipation when properly heat sinked. That little fin on the back is just not quite enough.

[@kg7wbw359]

Do you have a picture of the 817ND with this fan that you can link?

[@Relayer1974]

Super cool solution! Stay frosty. Puns intended. 73

[@branhamj368]

Neat solution. I had no idea you could dissipate heat that easily. I like the idea of the FT-817. I do not have one (yet) but like the compact size and ability to take it anywhere. As for other topics for videos, I would like to see some on getting up and running on some of the digital modes. Thanks.

[@loughkb]

I've thought about doing a vid on digital modes. My computers all run linux, so it would be specific to linux and not windows.

[@branhamj368]

Kevin Loughin that would be great! I am not a Windows guy but rather a Mac guy. It always bugs me that everything is for Windows.

[@loughkb]

You're running a version of unix, did you know? Apples OS is built on FreeBSD unix. At my last job, I built, maintained, and supported over 650 Mac workstations. All our servers were linux. A good investment would be a program called DiskWarrior. Apples file system is kind of broken. About 80 percent of the issues I dealt with at work were related to file system errors and corrupted files. Every mac user should get disk warrior and do a rebuild on their file system once a month as maintenance. It really keeps them running fast and reliable.

[@branhamj368]

Kevin Loughin yes I was aware of that. And I do have DiskWarrior! Very good advice. When I got started in computers I was completely a PC guy (no such thing as Windows at the time). I switched to Mac in about '99 and have never looked back. However it has made it more difficult now that I have got into ham radios as everything is Windows-based.

[@loughkb]

VirtualBox will let you simulate a whole PC and install windows. You can run windows like an application and get access to some things that way. On Linux, there's a neat program called WINE. It's a Windows API emulator that lets windows applications run natively under linux. I run Echolink using wine and it works fine.

[@alvarogaitan2529]

terrific tips thanks 73 from kb2uew

[@kg7wbw359]

This is a good idea. Without proper cooling, the finals will absolutely be ruined on full duty cycle digital modes. Yaesu recommends no more than 2.5 watts if operating digital modes like PSK31 or FT8.

[@loughkb]

The actual devices are rated at 10 watts continuous dissipation if properly heat sinked. I feel completely safe running the full 5 for reasonable transmissions at high duty cycle with the added sink.

[@frankmckinley1254]

Have you used heat transfer paste between the two flat surfaces? It should improve your heat transfer.

[@loughkb]

You can, but there's not really that much heat production. The mated metal surfaces seem to pull the heat away just fine. So, I didn't want to gunk up the outside of the radio.

[@normk7nwf323]

Has Yaesu made any improvements with the FT-818ND to address digital mode heating issues ?

[@ph4z_]

@@thorhilda Not sure I agree, the FT-81X is definitely built for digital modes, it has RTTY, PSK31, and USER digital modes. The reason not to include every digital mode under the Sun as a radio mode, is because the computer and software do the magic, the radio configuration is the same across. I agree there isn't an "issue" in the design to begin with. The user has the freedom to either add cooling, lower the output power, or accept the risks if operating at high duty cycles. Imagine the outrage if digital modes were limited at 2.5 W.

[@theodoresears4679]

I would added thermal paste to the heat sink.

[@loughkb]

The surfaces are flat and smooth enough that plenty of heat is transferred. The back of the radio hardly gets warm at all now.

[@ouijim]

Small Computer "Chipset" heatsink with fan may improve this idea? Thank You. . .

[@gertkok2113]

I was given a FT1802 2m VHF Yeasu, the guy wanted to toss it. It receives 100%, its just on outbound where its very soft Nice for just monitoring as I was also given a Vertex Standard VX2100 2m which does both ways 100% fine, its just that its a chanelised radio, and the FT1802 has a normal vfo. Any ideas buddy?

[@nontimebomala2267]

Thanks!

[@theodoresears4679]

does a dummy load act as Rx antenna. I had a dummy load to transmit up to a mile away.

[@loughkb]

No dummy load is perfect, they all leak a little RF.

[@jimbrownza]

Just wondering, seeing as you use that huge clamp, if a car battery copper jumper lead clamp just by itself and with the rubber grips off, would do the trick. 73 de Jim ZS6JMB ps and off topic.... how do you pronounce your surname? I'm wondering if it's Loffin or Lown or Loon?

[@loughkb]

Hi Jim, The clamp is plastic, so it wouldn't dissipate any heat. The first of your guesses is correct.

[@jimbrownza]

Ah no I didn't mean *your* clamp Kevin: I was wondering how a copper one off a battery jumper cable would do? But it also occurs to me they have quite ragged teeth and might not make good contact for heat.

[@kevinj8258]

Jim Brown I drilled a hole through the back right fin of the radio and through a heat sink. Just used a bolt and wing nut to tie it down. Works great.

[@jeromegrzelak8236]

Will a small fan work

[@theodoresears4679]

it would be nice modification if you had made permanent connected​ on that little rig.

[@loughkb]

No, I want to be able to remove it for stransporting in a small case or backpack. Things sticking out like that can be broken too easily.

[@jeromegrzelak8236]

Have u did the mic mod yet