[Yaesu] FT-990 phase noise
Thu, 3 Jul 1997 21:33:26 +0000
All modern HF radios do this. Most are spec'd at having this noise
60db below peak power. 60db below 100 watts is still quite a bit
of signal. It is one disadvantage of using a broad-band PA instead
of a tuned network. Older tube PA's had a PI network that would
not pass this. Try placing a good antenna tuner between the radio
and antenna, even if the antenna is a 50 ohm match. It may provide
enough rejection to clean things up. Don't forget good grounding.
Good luck. Dave WA0ZZG
> Date: Thu, 3 Jul 1997 11:16:11 -0500 (CDT)
> From: Bill Morris Denton <firstname.lastname@example.org>
> To: email@example.com
> Subject: [Yaesu] FT-990 phase noise
> This past fiel day we used my 9 month old FT-990 on the phone station.
> time we keyed up it wiped out the cw station that was 300ft or so away. We
> had to go to the old reliable TS-830 that was our back up radio.
> When ever the 990 was keyed in the ssb mode it produced white noise (for
> the lack of a better term) even without speaking into the mic. It was so
> bad that the cw guys raised cain and we had to take it off line. All this
> happened with both rigs on 20 meters.
> After I got home I did the same comparison. With the 990 tuned to the
> uppper end of 20 meter phone section and the 830 down in the cw portion
> and with no mic on the 990, I had a S9 noise signal out of the 990 on
> the 830. It sounded like open squelch on a 2 meter rig. USB and LSB
> had same noise. To confuse the issue I heard the same out of the 830 on
> the 990. Yet the cw guys didn't hear the noise on the 830. Of coarse
> the proxmity of the two rigs at home could account for some of it.
> Late Saturday after noon we moved the phone tower about a 100ft or so
> further away from the cw tower. We went back to the 990 later on but the
> noise was still a problem for the cwer's, but not a complete wipe out as
> it was before.
> I guess my question is has anyone experienced this problem with the 990
> or other rigs. I have heard of this happening some in multi-xmtr contest
> situations. In our situation the two transmitters and antennas had 300
> ft seperation from each other.
> We managed 2000 Q's from those two rigs but it was a struggle.
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