FT-857 Internal Meter

Yaesu FT-897: Interpreting Meter Readings (PWR, SWR, ALC)
– from the Yahoo group .. https://groups.yahoo.com/neo/groups/FT897/conversations/topics/34348

Power Ticks
5W 2.5
7W  3
10W 3.5
15W 4
19W 4.5
23W 5
27W 5.5
32W 6
36W 6.5
41W  7
44W 7.5
49W 8 (max. for psk-31 mode for 100 W transmitter)
56W 8.5
65W 9
84W  11.5 (9+2.5)
100W 14 (9+5) (this is full scale).

SWR SCALE CALIBRATION:
“tick scale” is 14 units

The “SWR” scale reads the ratio of V-reflected/V-forward. If we define
k = V-reflected/V-forward k ranges from 0-1 (i.e. what the 0-1 ma
analog meter would read) or 0-14 ticks on the FT-897 LCD scale.

SWR = (1+k)/(1-k) where k=0-1 = “ticks”/14

Using “t=ticks” directly, SWR=(14+t)/(14-t) with t=0-14

Note that SWR = 1 (1:1) when “t=0”.

using a 0-1 ma meter. The meter set to 1 ma on “forward” and then the reading
taken on the “reflected” setting. Old SWR meters are calibrated to show SWR=3 at mid scale (i.e. where k=0.5) since:  SWR=(1+0.5)/(1-0.5)=3

SWR Ticks  SWR=(14+t)/(14-t)
0 0
1 1.15
2 1.33
3 1.55 (Power starts to fold back here)
4 1.8
5 2.11
6 2.5
7 3 (here the high SWR “HSWR” starts to flash)

SWR indication is sensitive to the power setting. That is the SWR can go
up as power is increased if you do not have a perfect SWR=1:1.

THE “ALC” METER SCALE:
For psk-31 I adjust the sound card volume so that there is no ALC
indication. I adjust the volume into the rig until the “PWR” “tick
scale” shows a maximum of 8 (49 W) when the rig is set for 100 W (menu
075). There should be no ALC indication.


 
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