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  1. FT-857
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857D problem

 

I have had an 857D for quite a while which i have used mobile. At some point, I noticed some erratic behavior like screen flashing and someone reported my signal had a chirp and wasn't frequency stable.

So, I adjusted the menu so I could see the voltage reported by the radio. In RX, it looked ok; something like 13.5 or so. But when I keyed down in CW at 100 watts, the voltage reported by the radio display went down to 10.8. I tried making the wires feeding the radio larger, etc. with no change. I also tried it indoors on an Astron RS-50M power supply and note the same huge voltage drop. Power output is about 80 watts. Any ideas of what I should check? This couldn't be normal??
Kofi
 

Check your fuse holder. They can develop high resistance.

I wouldn't put much faith in the meter. I don't think it is particularly accurate when transmitting. Both my 857 would go around 10.8 when transmitting and they had no issues.

Leonard K. Pennock
AD7AS

Those who walk bravely through life, unafraid of loss or failure,
find that they very rarely lose or fail.

On 9/28/20 2:56 AM, Kofi & Mimi in Ghana via groups.io wrote:
I have had an 857D for quite a while which i have used mobile. At some point, I noticed some erratic behavior like screen flashing and someone reported my signal had a chirp and wasn't frequency stable.
So, I adjusted the menu so I could see the voltage reported by the radio. In RX, it looked ok; something like 13.5 or so. But when I keyed down in CW at 100 watts, the voltage reported by the radio display went down to 10.8. I tried making the wires feeding the radio larger, etc. with no change. I also tried it indoors on an Astron RS-50M power supply and note the same huge voltage drop. Power output is about 80 watts. Any ideas of what I should check? This couldn't be normal??
Kofi
pete
 

On Mon, 28 Sep 2020 02:56:10 -0700
"Kofi & Mimi in Ghana via groups.io" <kofigbleze@...> wrote:

I have had an 857D for quite a while which i have used mobile. At some point,
I noticed some erratic behavior like screen flashing and someone reported my
signal had a chirp and wasn't frequency stable.

So, I adjusted the menu so I could see the voltage reported by the radio. In
RX, it looked ok; something like 13.5 or so. But when I keyed down in CW at
100 watts, the voltage reported by the radio display went down to 10.8. I
tried making the wires feeding the radio larger, etc. with no change. I also
tried it indoors on an Astron RS-50M power supply and note the same huge
voltage drop. Power output is about 80 watts. Any ideas of what I should
check? This couldn't be normal?? Kofi




I am going to say exactly the same as Leonard

Fuse holder do away with the fuse in the negative line not needed as for the
meter reading not very accurate just an indication really check see if
there is a voltage drop across the standard Yaesu connector it does happen


Does not solve my button problem thou

Pete .
 

Kofi,

Check the wire entering the fuse holders,? I recently found mine were discolored from heat caused by a bad connection. I replaced the fuse holders just to make sure I fixed the problem.? My FT857 had large round fuses, I replaced them with the spade type used in cars today.? One way to check to see if that is where the voltage drop is measure the voltage across the fuse holder while transmitting.? I be that is where you are losing the almost 3 volts.


Good Luck & 73,

Wes
WA5TKU
 

On Tue, Sep 29, 2020 at 12:31 AM, pete wrote:
do away with the fuse in the negative line not needed
It kind of is.

In an automotive situation if the battery negative to chassis connection fails it's possible a *lot* of current will try and find its way home via the radio. It's not a likely situation but is possible. Having said that I only use one fuse on mobile rigs and no fuses at all on my bush radio but simply a 1m lead to a battery.
 

Rather than hook the ground to the battery, hook it to the same point the battery connects to the chassis and the issue cannot occur.

Leonard K. Pennock
AD7AS

Those who walk bravely through life, unafraid of loss or failure,
find that they very rarely lose or fail.

On 9/29/20 2:20 PM, James Clark wrote:
On Tue, Sep 29, 2020 at 12:31 AM, pete wrote:
do away with the fuse in the negative line not needed
It kind of is.
In an automotive situation if the battery negative to chassis connection fails it's possible a *lot* of current will try and find its way home via the radio. It's not a likely situation but is possible. Having said that I only use one fuse on mobile rigs and no fuses at all on my bush radio but simply a 1m lead to a battery.
 

I have hooked the ground to the same point the battery connects to the chassis and the problem is resolved now.
Kofi

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