[Yaesu] Re: Yaesu digest, Vol 1 #707 - 5 msgs

Thu, 12 Feb 2004 10:38:45 +0000

on 12/2/04 9:07 am, [email protected] at
[email protected] wrote:

> Message: 5
> From: "John Nelson" <[email protected]>
> To: <[email protected]>
> Date: Wed, 11 Feb 2004 21:24:04 -0000
> Subject: [Yaesu] FT-1000D auto ATU question
> 
> Folks:
> 
> Something a little strange seems to be happening with a colleague's FT-1000D
> that I've just been fettling for him. If you reset all memories and then
> 'train' the auto ATU at four or five spot frequencies in each HF band, it
> seems reasonable to expect it to deliver the set power at any frequency in
> the band. However, this one doesn't produce full power on some particular
> frequency unless you press the 'start' button before transmitting. If you
> don't it delivers about 80-90W until you do. However if you switch the tuner
> out (whether into a dummy load or an antenna which presents a good match) it
> delivers full power.
> 
> Is this behaviour normal for the FT-1KD? If not, any suggestions as to where
> to look to fix it? My FT-990 doesn't display this phenomenon.
> 
> 73 John

Hi John,

This would not seem to be that strange.

It could be effected by any number of factors, slight difference
in design in the atus between the 990 and the 1000 etc.

However I suspect the main reason is due to the difference in power output.
If memory serves me correctly the 1000D is rated at 200w while the 990 is
100w.

If the match the transmitter is look at is not 1 to 1, and it probably
isn't, the the increase in power from the 1000 would also see an
increase in the reflected current.

One of the drawbacks of trying to use wide-band, multiband antennas I'm
afraid.

Very common when using some sort of linear amp. If you set-up the tuner
using just the drive from the rig and then switch in the linear invariably
you will see an increase in the SWR and therefore need to retune.

It's nothing to worry about and just something to live with unless you have
the perfect antenna system which will produce a 50ohm load on every single
frequency on every single band.

If you ever do find such a thing do let the rest of us know, I've been
looking for one of those for years:)

Hope this helps,

Kind regards,

Sean.