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So a low battery voltage could blow the finals?

Yes. The problem principally affects the original, pre-2004 or so, FT-817, not FT-817ND which uses a revised PA with different output transistors.

Any idea of the voltage? Is it less than the official minimum operating voltage of 8v?

The Death Hoot is a spurious oscillation. As the voltage drops, so the PA transistors' internal junction capacitances change, which can enable a (spurious) oscillator circuit. It is not a readily quantifiable circumstance, except to say that it has happened to quite a few PAs. The new design PA has far more robust output transistors, and can be fitted in place of the original design.

At what voltage does the 817 power down?

My recollection—but others must provide a definitive reference—is that auto-power-off is at around 7.8?V. [Presumably under processor control.]

In theory 8v is the voltage that the 9.6v battery pack falls to when the batteries are almost flat...but this assumes all the cells are balanced and deplete at the same rate.

With the original (or replacement!) battery pack, the PA, which is permanently connected to the power rail, will drain the battery in about 6 months or so. The current drain from the PA is not specified, and the design assumes that the battery will be regularly recharged. If this is not the case, then a flat battery will result. If it's left then a dead battery pack is the outcome, since there is no auto-disconnect of the permanently powered circuitry.

IIRC, the FT-817 was designed for the JA equivalent of the UK novice licence, and assumed frequent use.

HTH, 73, Stay Safe,

Robin, G8DQX

Swap the right hand ends of the two switches in the diagram

On 2022.04.30 2232, Ken N2VIP wrote:

One of the great frustration many US FT-817/818 owners have is that the
receiver can not pick up the US National Weather Service VHF broadcasts,
it is a hard limitation of the FT-817/818, the reason for which I can
only speculate on.

Ken, N2VIP

On Apr 30, 2022, at 23:20, g8tzl2004 via groups.io
<g8tzl2004@...> wrote:

?Any reason why the 817 only covers up to 154 MHz rather than 175 MHz?

All my other Yaesu VHF radios have 136 - 175 MHz RX ?

I guess there must have been a technical issue in going beyond 154 MHz RX?

Has anybody modded an 817 to provide RX up to 175 MHz?

Sure,

Environment Canada also has Weather Radio Canada in that range. It's also the Shore Transmit range for Marine VHF and near to North American rail frequencies. None of these mean there'd be any need to include them in a ham rig.

So, Why: it's 1. a ham rig, 2. designed to replace the FT-690, FT-290, FT-790 -- no need to include anything other than ham radio coverage., and lastly, designed in a country, for a world, that has no NOAA/Wx Rdo Can (other CANUS.)

If you need/want it on/with one radio, try a converter. There used to be the MFJ-313 VHF Converter. The schematic for the MFJ one is in the Files area for this list. There are other possibilities to acquiring one, having one made, making it oneself.

73, John VA7OTC

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One of the great frustration many US FT-817/818 owners have is that the receiver can not pick up the US National Weather Service VHF broadcasts, it is a hard limitation of the FT-817/818, the reason for which I can only speculate on.

Track cuts? Please elaborate.?

-n7hex

Is that a common mod?

I guess my fingers are too big!!

Any reason why the 817 only covers up to 154 MHz rather than 175 MHz?

All my other Yaesu VHF radios have 136 - 175 MHz RX ?

I guess there must have been a technical issue in going beyond 154 MHz RX?

Has anybody modded an 817 to provide RX up to 175 MHz?

Two track cuts and two lengths of wire, and it'll be just how you like it.

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I guess the great FT-817 was not made with you in mind. ?I find no issue with it.

I find it difficult to press the Function key given its location next to the tuning knob.

The Function key should have been located where the Lock key is positioned?

Any views?

But the official 1400mAH NiMH pack is being charged at around C/5 so its not being "trickle" charged.

Any views on using a fused AA battery box when using 2600mAH LSD Eneloops.

Can thin round fuses be purchased that will slot between AA batteries ie same diameter as an AA battery? I guess one could be made with some stiff thin plastic and thin copper tape?

Any views on charging Eneloops inside vs outside the 817?

So a low battery voltage could blow the finals?

Any idea of the voltage? Is it less than the official minimum operating voltage of 8v?

At what voltage does the 817 power down?

In theory 8v is the voltage that the 9.6v battery pack falls to when the batteries are almost flat...but this assumes all the cells are balanced and deplete at the same rate.

Sounds like it, then.? I'll be working on the? house and will leave it in time -- 80 will be more than I can do more than than I can sell it.

?

Cortland

Hello,?
Yes the 817 wild rain the battery over a piriod of time. The main problem is not the batteries but the Finals. When the voltage and current lowers to a point it will cause problems and could blow the finals.?
This has been noted for years. You will find many posts on the subject in the files area.
I have purchased a replacement WINDCAMP battery door that has a switch built in that completely disconnects the batteries for any storage time.
You will find them listed on Ebay. Also listed is the WINDCAMP lithium 3000 mah batteries designed for the 817 & 818.
I have been using one for over 3 years in mine.?
Clyde Lambert KC7BJE?

NiMH and NiCd can both generally take C/10 overcharge indefinitely (well for many hours). So timed charge is fine, even if they are half charged when you start. (my '817 is 260mA)
Originally NiMH calls had substantial leakage current, and self discharged in perhaps 6 months without use.
Nowadays, you should be sure to only buy LSD (low self discharge) also sold as "precharged" NiMH. e.g black eneloop pros.

They also have limited life,?Energiser say: "However, battery life is limited to 5 years or less." and "Typical expectancy?life?is 2 to 5 years."

They will heat up during the overcharge phase, which makes dTemp an excellent end of charge indicator.
-dV is commonly used to automatically end charge, but it also works because the battery is heating up i.e. dV/dTemp is -ve

The original FNB-72 battery pack is NiCd.? That charges perfectly fine with a constant current charge.? The timer allows you to select a shorter time depending on what you determine to be the state of charge on your pack.? With constant current charging, once the battery is at full charge, the extra current generates heat.? So yes it is possible for the battery to get warm during charge.? I would not recommend that you charge a battery that is already warm, charge while the radio is in the sun or with the radio enclosed (in a box or a go-to carrier).

--
Al Skierkiewicz
WB9UVJ

On Sat, Apr 30, 2022 at 03:14 PM, g8tzl2004 wrote:

I guess Yaesu must make a significant profit on selling new battery packs to replace all the killed packs...otherwise I can see no other reason for not having an "intelligent" battery charging system!!

I don't think many FT-81x owners buy Yaesu replacement battery packs. When I was active in the 817 owners community, the norm was to either put high capacity NiMH AA cells into the dry battery tray, or to purchase external battery packs if you wanted longer running times. Also don't forget that the design of the 81x has changed very little since the original release - and that came with NICADs - no need for intelligent charging there...

Martin (G8FXC)

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Hi

I think the thing that kills the batteries is the fact that people turn them off and leave them set

to allow the battery discharge to past the charge that will make it short. Then the self oscillation

in the rig kills the battery and maybe the finals also.

My FT-817 was made in 2001 and still has the same finals. I have always removed the batteries

when it was to set on the table for a while. Now I leave it plugged into a power supply and use it

that way as portable operations are not available to me at this time.

Marty kd8bj

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Same boat here, my original pack lasted 4 years and about 200 charge cycles. ?I thought it a bargain, and 3 sets of Eneloops handled the last 15 years.