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Drifting FT-857


#1

Hi,
My Yaesu FT-857 seems to be drifting off frequency.
This is especially noticeable when using 2m ssb rather than FM.
Any ideas?


#2

In reply to G1STQ:

Is this in the shack or on the hillside?
How fast does it drift?
Does the drift occur only when first switched on or after the 857 has been on for a long time?
Does it drift one direction on receive and then change direction after a long over transmitting?

Andy
MM0FMF


#3

In reply to G1STQ:

Just a thought, I know its improbable, but if you have left a small offset on the clarifier - you go over, find the other guy is off frequency and tune him in, then he finds you now off and retunes you, and you chase each other slowly up or down the band?

73

Brian G8ADD


#4

On 2m SSB at my FT-857 I often have to set a QRG that seems to be fixed 100 Hz to low. Until today I never noticed that it is drifting.

I saw this also in a video from Ed ON4EDM with his FT-897

73 Jörg DL1DLF


#5

In reply to DL1DLF:

Hi Joerg,

I get the same with my FT-857, -typically to receive
a station on 144.300 I would tune 144.299.92, but my
transmit/receive frequencies appear to be matched ok.
The FT-857 seems to be spot on frequency on HF.

Kind regards

Dave G0ELJ


#6

Hi,

The FT-857D (EU version) usually has a high stability TCXO fitted that was an added option on the FT-857.

The frequency stability of the TCXO is quoted as ± 0.5ppm (parts per million).

This equates to ± 72.5Hz at 145MHz, or a total possible error range of 145Hz.

As for an original FT-857 without the TCXO fitted, it would be considerably worse.

10GHz SSB operation can be fun when even ±0.5ppm is ±10kHz!

Cheers.

Ian.


#7

In reply to GW8OGI:

10GHz SSB operation can be fun when even ±0.5ppm is ±10kHz!

Ian,

You hit the nail on the head! Even in the 1296 MHz band too I regularly notice 1-2 kHz deviance of the conterpart’s frequency (having arranged a sked during a QSO established at 432 MHz) compared to my display! Of course 10368 MHz is 10x as difficult… Please note that in the microwave bands we commonly use 144 or 432 MHz basic RIG plus a converter, so the frequency drift and offset depends on more than a single factor!
Skilled microwave operators, in order to be more effectice and successful, maintain records on frequency deviation of different stations noticed during previous contacts! Based on this information they can start searching XX0XXX at -23.4 kHz while YY0YYY at +23.4 kHz! :slight_smile: In case of new initials you don’t have any clue where to start searching. :frowning:

73: Jóska, HA5CW


#8

In reply to G1STQ:
So it appears that I am not alone…
The radio can slowly drift up from, say 144.300.00 to 144.300.20
Seems not to do it on hf though, although I tend to keep this radio mainly for vhf and uhf.
Appently tx and rx drift together…


#9

In reply to G1STQ:

All I can say is that my FT-857D does not do it, mine is as steady as a rock on all bands.

Does your rig have the high stability TCXO? If not, it can be purchased for after-market installation.

73

Brian G8ADD


#10

In reply to G8ADD:
Hi Brian,
Yes, it’s the 857D so it should have the better TXCO (I think!)…
I am just trying to save what will end up being quite a few beer tokens if I book it into Radioworld for them to have a look.
At the moment, I can cope with it’s unusual character and hopefully keep £100+ for more essential items, such as a 2m beam!


#11

The FT-857, FT-857D and FT-897 comes without the TCXO, but can be build in as accessories. Only the FT-897D comes with the TCXO integrated from factory.

73 Joerg