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FT8 Operation
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Jack Sheehy
Hi Folks,
I wondering about others' experience using the FT-857D on the FT8 mode.? I am currently running FT8, successfully, using an SCU-17 and making contacts on 80 thru 10 running 40 watts.? Because of the compact size of the radio, I am concerned about overheating (BTW, the fan has been operating fine).? What have others experienced?? Any suggestions are welcome. Thanks, Jack W1JS NH?? |
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I ran my ft-857 at 50 watts on 6m (FT8) non-stop outside in 90+ degree weather in the Dry Tortugas a few years ago without any problems. I will say it wouldn't push much more power than that and I didn't want to push it beyond that but it did fine. Ryan WG4I On Wed, Nov 4, 2020 at 11:29 AM Jack Sheehy via <j_sheehy=[email protected]> wrote: Hi Folks, |
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Theo Marinos
I've made plenty of JT65 and FT8 contacts with my 857D whilst installed under the passenger seat of my car and haven't had an issue. Obviously I wouldn't do it at full power but I'd estimate I'd be running it at around 75 watts or so. Regards Theo VK5IR On Thu, Nov 5, 2020 at 2:59 AM Jack Sheehy via <j_sheehy=[email protected]> wrote: Hi Folks, |
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On 04.11.2020 17:29, Jack Sheehy via groups.io wrote:
I wondering about others' experience using the FT-857D on the FT8 mode. I am currently running FT8, successfully, using an SCU-17 and making contacts on 80 thru 10 running 40 watts.? Because of the compact size of the radio, I am concerned about overheating (BTW, the fan has been operating fine).? What have others experienced?? Any suggestions are welcome.Just keep power down to not higher than 25W (5W would be even better) and it will be ok. -- 73, Pedja YT9TP Checkout: |
¿ªÔÆÌåÓýHi Jack, I am using dairy my almost 10 years FT-857D
on FT8 mode, full power (~110w) using an Rigblaster advantage
and an delta loop antenna which is perfectly to very good tuned
on 40,20,15 and 12m. For 80, 30 and 17m, I use an LDG AT-200Pro
II tuner. That's said, during last summer because each year it
is hotter on my area (living N.E. France in countryside) I
bought an Noctua NF-A15 HS-PWM Fan. I put the fan over my rig,
about 1/4 is over the heat sink of the rig, the rest is over the
rig. As it is a big fan, a very good part of the rig is cooling
very good. Anyway for other mode where duration is longer I will
use and used less power. 73 de Thierry, F4GVO Le 04/11/2020 ¨¤ 17:29, Jack Sheehy via groups.io a ¨¦crit?:
Hi Folks, |
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Group, I have been using the FT-857 on FT-8 and JT-65 from home and DX expeditions mainly on 50 MHz. Usually I run full power. I have not seen thermal issues, but mostly I am on top of mountains. There seems to be one fundamental issue with the 857 in its SSB modulation circuit. We have analyzed multiple?857 and looked in deep into the circuit and probed every stage on the modulation path.? The 857 has rather strong distortions in its SSB modulation path. For example, if you drive it with 600Hz, you will see, rather strong 1200 and 1800 Hz. This is not a function of the power level. This is caused in the modulation circuit. The reason is the modulator IC selected. It is driven beyond specification on the audio port, thus, it distorts. Other rigs, like my Kenwood 480 are much better in this regard. This problem normally unnoticed, some people think that the SSB audio sounds somewhat not really clean. But in FT-8 this grows to a serious issue. For example, if you transmit at 50.3135 MHz (so 500 Hz audio) you will also transmit at 50.314, the second harmonic of the audio. The harmonic signal is like 40 or 60dB down, but if somebody else uses that frequency you will block it if the stations are close to each other, or if you are on an excellent location on a mountain. People will start to complain about your signal having spurious. In FT-8 this matters, as teh actual used bandwidth is just 60 Hz.? After analysing this issue on multiple 857 and understanding the circuit from probing I stopped using the 857 for FT-8. 73? ? ? ? David? ?OE6NZM / AD0PY / DL7ZM? now in Graz, Austria On Thu, Nov 5, 2020 at 8:06 AM YT9TP - Pedja via <yt9tp=[email protected]> wrote:
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YT9TP - Pedja
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