Ft817 or ft818

What about installing a Laserbeam filter? Won’t some of the (somewhat essential) aftermarket mods void the warranty anyway?

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FT818 is the future. For FT817 the support will end soon.

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I ended up with a FT818ND found a few 817 but either too far away or sold very quickly so i saw a 817 in a shop and a good price , i went down today and was sold today so i ended up buying a 818 instead of a wasted journey . acording to ML&S yaesu will surport parts for the 817ND for 10 years

Matt 2E0FGX

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I’m working on an amp for hf/V/UHF. External liPoFe of course but will not be biased on until TX…

For mobile ( and base too ) and a few SOTA or POTA . I’m using a MiniPA100w with a lowpass filer , all automatic control based on band data from radio …

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By adding 1W, 818 ceased to be QRP … By the way, in 817 you can easily set up and 10W in a minute.
vy 73 de Mariusz sp9amh always QRP with 817 (5W max)

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Czesc Mariusz,
Easy? Are you sure? That’s not what I’ve read about that.
Can you explain the easy method you seem to know, please?
Thanks.
73,

Guru

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Please take care, Guru. 3db or 1/2 S is not a big step. A clear, bright modulation by a voice compressor brings significantly more.

73 Chris

Thanks Chris,
In the mean time, I’ve googled for this and found this other method by MM0BFF and it seems simpler than the one you posted.
FT-817 Increased Power Ouput - Radioaficion

I don’t think I’ll attempt to increase power output to any of my 2 currently owned FT-817s.
Only asked that question because the method I recalled having read long time ago seemed quite complicated and risky to me. This new method by MM0BFF seems far easier and less risky.

73,

Guru

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Hi Guru and Mariusz,

I have several comments on this. First, the original version of the final amplifier for the 817 was more sensitive than the 817ND to mismatches and many failures occurred, the early rig gaining a reputation for failures caused by high SWR. So I would not recommend increasing the output power setting to the extent suggested in the article. The 817ND final stage is more robust so a higher power level may be more tolerable by that model and the 818.

Having said that, the fact is that a doubling of output power creates only 3db more signal, tripling the output power is only 4.7 db. Will you make more contacts with such a small relative increase in power? Only in the worst conditions. Arguably we have had bad conditions in the last two years but things are improving. For ssb an external speech compressor can create the audible signal level increase of at least 4.7 db, without modifying the radio at all.

The next matter is that the article does not contain the essential advice to record the existing settings of all those parameters. You will need those at some time in the future, otherwise the radio has to be reset to standard power levels by someone else, using power meter etc. These settings are not identical for each radio, due to the variation in stage gains with specific devices. Record each setting before changing any,

It is possible to make the 817 sound pretty bad and generate a wider signal if the IF gain is set too high as it causes excessive ALC action. In addition, running the final amp at higher power means the peak RF current and voltage is increased. This means it is even more sensitive to mismatched loads, ie. high swr. You need to take care of this situation by monitoring swr very carefully, otherwise you will be buying a new final amp module soon.

Minor quibbles: The article suggests that the power lead should be increased in size, really? The current drawn by the power supply is only doubling.

Heat dissipation. The rig has a thermal design that uses the (very) heavy chassis to dissipate heat, as discussed recently by ZL1THH. Doubling the power level will double the heat to be dissipated. The radio will run hotter.

The article does state that if you make the changes suggested, you are responsible for any failures that result. This is a risk that owners of radios under warranty may consider too high.

73 Andrew VK1DA/VK2UH

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Thanks Andrew for you comments and insights.

73 de Geoff vk3sq

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I ask myself if Yaesu simply realised that they could squeeze an extra watt out of the 817 finals without changing any components at all. 1 watt is a such a miniscule increase, I would be very interested to know exactly which component had to be swapped out to allow it. Would I go for the full 10w increase? Definitely not. If that were possible without either exceeding the tolerances of some downstream components, or changing the emissions profile, then Yaesu would surely be doing it already. Maybe 7W…
Some measurements with a spectrum analyser would make a good YouTube video.
73 de OE6FEG
Matt

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Last year my 19-year-old FT817 would occasionally power off [always mid QSO, mid activation]. I thought perhaps it was TX RF upsetting my external Tracer LiPo’s current-overload sensor but subsequently found that the FT817’s 12V DC socket was a bit loose / intermittent. I fitted a Powerpole adapter / cable [from SOTAbeams - other solutions are available] and have never had the problem since.

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Hi All!
The relevant values can be changed in the service menu. But it is risky, and I did not it it at home. What a difference of 5 or 10W 3dB !! Half S. Risk too high. Especially when we use not fully tuned antennas. Not all specimens have an adequate supply of control, so it will not always be successful.I only calibrated the supply voltage (V) indications in this menu.
Before someone dares to rummage in this menu, he should rewrite all the settings on a piece of paper so that you can come back and not make the radio a brick …
Sometimes it will be only the 6W as in 818. I think that Yaesu has not changed anything there, only the settings themselves because many people take advantage of these 0.8dB profit on power … just like women on the prices of $ 1.99 (for me it is 2 and for my XYL 1 … hi)
Mariusz QRP-man

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No component changes would be necessary, it would all be done by simply setting the IF gain to a slightly higher value and adjusting the power limiting setting to one that allows 6w instead of 5.

73 Andrew VK1DA/VK2UH

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As an aside, I measured the voltage drop on my 817 cable with in-line fuse as supplied. Running 5w of fm from a 12v supply, the cable dropped 1v. If you were to double the current draw, then the drop would be 2v, which might mean that you couldn’t use the full capacity of your external battery.
I have no intention of modifying my 817, but a thicker cable is perhaps the more sensible suggestion!

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Or don’t run FM…

But seriously, the supply voltage is only used for the final amplifier, which has sufficient gain to produce 5w on any voltage higher than 9.6v because that’s the voltage the internal NiCd or NiMH battery produces (8 x 1.2v).

The rest of the radio is run off a subregulator that drops the incoming voltage to an internal voltage less than 9.6v. The voltage difference between that an the incoming voltage just turns into heat in the regulator. So that current may as well heat up the power cable.

One of my 817s has the LIPO installed, which starts at 12.4 on full charge, drops down below 12v fairly soon, spends a lot of time showing 11.x and 10.x volts, finally when it gets below 10v I stop using it and plug in an external battery. I just did 3 activations with the 817 and it is still not below 11v. But then, I don’t use it on FM.

73 Andrew VK1DA/VK2UH

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I shortened my cable from about 2m to 1ft. (Gotta love mixing units). OK, 30cm. I was more concerned at the weight of the extra cable and as it was always coiled up, snipping it much shorter made sense.

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Context: I’ve just bought a replacement LiFePo 4S2P battery - the old one lasted about six years, and one cell has just given up and swollen.
I wanted to check the voltmeter calibration on the 817, which involved determining the drop in the cable.
As Andrew says, it all works out quite nicely in practice. The battery can be run down to 2.5v per cell minimum (assuming perfect cell balance, I would actually allow a margin of safety). If there is one volt drop in the cable, that still delivers 9V to the radio.
The 817 voltmeter actually reads low, so that gives me the margin of safety!

I took the measurement on FM because my AVO 8 MkIII doesn’t have a peak hold function, but I assume the SSB peak current will be simillar. I do have a DVM with peak hold, but hey, I haven’t worn out the AVO yet :roll_eyes:

The drop in the cable might be more significant to someone using an external 3 cell LiPo…

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The one item missing from this discussion is the rx performance. I run an 857 at 50 w of SSB or cw HF and 25w of FM on VHF. The downside of the radio is the rx intermod performance, when the"zoo" is more than 5, calling simultaneously.

At home the rx in my Orion is so much better in this regard. Hence the KX3 or 818 should not be discounted. Remember the 817/857 design is now 20 years old. Progress has been made.

Regards
David

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I agree that the intermod performance is not up to the standard of more recent rigs, but where else can you get an all mode rig covering Top Band to 70cms that is no bigger than a box of chocolates? When this progress results in a complete competitor to the 817/818 then I will transfer my affections, but it hasn’t happened yet!

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