[1000mp] IF Gain Menu Setting -typo

[Tod -MN]

My apologies -- there is a typo in the next to last paragraph. Here is the
correct text:
 
Again, one would use their ear to make the 'signal to noise ratio' decision.
On the other hand, you could connect a multimeter, set to measure  AC
voltage, to the speaker output. Adjust the RF gain to get a very small,
non-zero reading with no external signal. Then inject the external signal
and measure the speaker output voltage. The IF setting that produced
greatest difference would be the largest signal to noise choice.
 
Tod, K0TO
 


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From: 1000mp-bounces at mailman.qth.net [mailto:1000mp-bounces at mailman.qth.net]
On Behalf Of Tod -MN
Sent: Sunday, February 08, 2009 11:33 AM
To: 'All about Yaesu 1000mp'
Subject: Re: [1000mp] IF Gain Menu Setting


This sounds like a good way to do things -- especially if one has little or
no test equipment [most folks fit in this category].
 
I wonder if it might be possible to modify the procedure slightly to be able
to 'read a meter' and still get the correct spot. It is probably not really
necessary since one is most likely only selecting between three different
gain values.
 
The ",, very weak birdie that's just barely detectable in the noise (or
generate such a signal) on the 12 or 10 Meter band." sounds like one is
trying to get to the place where the AGC of the radio is not influencing the
outcome. I would suspect that one could do that same thing by turning off
the AGC using the front panel switch. Then  one might inject a signal that
is just above the noise level using a signal generator connected to the
FT1000X or another transmitter connected to a dummy load that can be heard
by the FT1000X. If you are injecting the signal as mentioned above instead
of picking it up from an 'antenna', it probably would be a good idea to
connect a 50 ohm dummy load to the antenna input so that the front end has
the impedance it was designed for. A 1/4 watt 51 ohm or 47 ohm resistor, if
it is non-inductive, would certainly be adequate
 
 
Again, one would use their ear to make the 'signal to noise ratio' decision.
On the other hand, you could connect a multimeter, set to measure  AC
voltage, to the speaker output. Adjust the RF gain to get a very small,
non-zero reading with no  and then measure the output with no external
signal. Then inject the external signal and measure the speaker output
voltage. The IF setting that produced greatest difference would be the
largest signal to noise choice.
 
 
I would like to say again that I suspect doing it with meters is overkill;
using "ear" method is most likely entirely satisfactory. Switching off the
AGC in either case would assure that the result will not be influenced by
AGC action.
 
Tod, K0TO
 
 
 
 


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From: 1000mp-bounces at mailman.qth.net [mailto:1000mp-bounces at mailman.qth.net]
On Behalf Of wjs073 at bellsouth.net
Sent: Sunday, February 08, 2009 9:05 AM
To: 1000mp at mailman.qth.net
Subject: [1000mp] IF Gain Menu Setting


The gain setting is adjustable to take unit-to-unit variations into account.
There is no single setting that is proper for every radio. The procedure I
read, which made a lot of sense to me, was as follows. Find a very weak
birdie that's just barely detectable in the noise (or generate such a
signal)
on the 12 or 10 Meter band. Now adjust the IF gain setting to maximize 
the signal to noise. Too low a setting causes both the signal and the noise
to drop. Too high a setting causes them both to increase. But there is a 
point, which may be over a range of two or three numbers (i.e., 12 to 14),
where the signal stands out a little better against the noise. Close your
eyes and listen very closely while changing the setting up and down.
You should be able to find this "sweet spot."
 
DE K3AN
 

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