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[SPAM] Re: [Yaesu] FT-1000D Audio Distortion

To: <yaesu@contesting.com>
Subject: [SPAM] Re: [Yaesu] FT-1000D Audio Distortion
From: "Dick Zseltvay" <dickzs@comcast.net>
Date: Sun, 23 Mar 2008 19:27:42 -0500
List-post: <yaesu@contesting.com">mailto:yaesu@contesting.com>
David, I would suggest checking several settings before you try modifications 
on the receiver itself. The symptom that you're describing could come from too 
much RF amplification.

A number of selections on the FT-1000 effect RF levels. Audio distortion is a 
hallmark of over driving the RF amplifier. The following controls all interact 
with one another so any one or a combination of several could be the source of 
the audio distortion from too much RF amplification. 

The two noise blankers (NF, and NBW), the Front END control, the AGC control. 
And of course, the RF gain control. Keywords: that you mentioned include 
"strong signals". Given conditions such as this one should be using they some 
level of attenuation. The NOR position adds further RF amplification to a 
signal (RF preamplifier is switched in). With the switch in the IPO position, 
the signal bypasses the radio's preamplifier and it is injected directly into 
the first mixer. As mentioned earlier, one of the positions for attenuation 
should be selected. 

The AGC control also affects RF amplification as well as possibly adding 
interference to the audio signal. Under the conditions you described, the AGC 
control should be set to on. The AGC control in tandem with the RF Gain control 
can add interference in both the RF and IF (amplifier) stages. The following 
settings guarantee audio distortion: the AGC control set to OFF, the RF gain 
control set to a high level (turned clockwise).

With a single side band mode selected the AGC control should be set to the 
medium or slow position. When the mode is set to CW the AGC control should be 
OFF or set to the fast position.

The above gives the idea: too much RF amplification gives audio distortion. 

Dick Zseltvay, KC4COP
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