[Icom] Power meter on my 706 MKII

[Ray, W2EC]

In very basic terms, the MKII meter default setting is to read PEAK 
power so that people feel they are getting full power since they see the 
meter go full scale. The SX200 is reading AVERAGE power so it is reading 
a lot lower than PEAK power. If you replaced your SX200 with an power 
meter that could switch between PEAK and AVERAGE, you would see roughly 
40 watts out in the AVERAGE position and 100 watts out in the PEAK 
position. You could also go into the MKII menu settings and turn PEAK 
HOLD OFF (PEAK HOLD ON is the default).

It has to do with the characteristics of SSB. Since there is no carrier 
most of the time, and voice peaks (max power) are infrequent, the 
AVERAGE power displayed is considerably lower than the maximum PEAK 
power out. A mechanical meter returns to ZERO quickly and without 
special circuitry cannot respond to show the PEAK power. Meters with the 
PEAK circuitry slow down (dampen) the return rate of the meter so that 
more of the power is displayed on the meter before the meter needle 
begins returning to zero. Therefore it is capable of displaying the 
highest wattage encountered. CW and RTTY are full carrier so both meters 
will display the PEAK power because PEAK and AVERAGE are the same for 
CW/RTTY.

I guess the PEAK default is set to ON because if it were OFF then the 
MKII meter would only display AVERAGE power and people would be 
questioning why they weren't getting full power out when they 
transmitted in SSB.

73, Ray  W2EC

sasi nayar wrote:

> Hello Icomites,
> 
> I have a MKII that I use as a base. While making some
> measurements a few days ago, I realised that the power
> meter on my MKII was way off on SSB compared to what
> is registered on my Diamond SX 200 power/SWR meter.
> Everything else works fine..its just the power meter.
> SWR indicator is close to what is registered on the
> SX200.
> 
> When I key down on RTTY and CW, both mode registers
> close to 100W. I go on SSB, the meter on the radio
> indicates full power while, the actual power output as
> seen on my SX200 is only 50W. There is no RF loss as
> the SX 200 is in line with the radio and the antenna
> tuner. The SX 200 is connected to the radio with a
> short stretch of coax (about 30cm). Has someone
> noticed this on their radios? Is there anyway we can
> calibrate the meter? 
> 
> When I had my station inspection done a few days ago,
> the inspector mentioned that he had observed this with
> most radios. I doubt his statement as there is no
> point in having a 'way off meter' on a radio when it
> does not serve its purpose. Just my thoughts
> 
> In anticipation for your inputs
> 73
> Sasi
> 9V1SM
> 
> 
> =====
> Amateur Radio For Global Peace and Fraternity
> ----------------------------------------------
> Sasi Nayar, 9V1SM / VU3SNM, 
> Reef Ecology Lab, Department of Biological Sciences
> National University of Singapore,14 Science Drive 4
> Singapore 117 543. Tel : (65) 6778 7112 URL:http://www.dbs.nus.edu.sg/lab/reef/SasiNayar.htm
> 
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