TX power level changing (Buxcomm, Win 7, TS-440S)

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Joined: 2014/08/24 - 00:13
TX power level changing (Buxcomm, Win 7, TS-440S)

I'm a fairly new user of WSPR (2.12), and have noticed that when I shut my radio down overnight and then attempt to start using WSPR again the next day, I usually have to make adjustments in the TX level on my Buxcomm interface to keep the transmitted power at 5 watts.

I'm a new ham, so I'm not sure if this would be related to different conditions on my outdoor antenna (moisture, etc.). I've got a W8AMZ G5RV Jr. that is suspended horizintally within some foliage.

I'm measuring the power on both the radio's built-in power meter and an external Daiwa meter that I have connected between the radio and my antenna tuner. I'm not adjusting the built-in antenna tuner nor the external antenna tuner during/between these sessions. I'm also not running any programs or making any changes on my PC during this time. It just runs a screen saver, and does not hibernate/sleep. It is running Windows 7.

When I "shut things down", I click the "Idle" check box in WSPR, set the "TX fraction" slider to 0 (hey, you can never be too careful!), power off my radio, switch my external antenna tuner from the antenna to a dummy load, and disconnect my outdoor antenna. I reverse this process when going back on-line, and then click the "Tx Next" button to get a transmit cycle going. I usually find that I have to adjust the TX level control on my Buxcomm interface to get the power back to 5 watts (if it's off, it's usually by no more than, say, 2-3 watts).

The reason this concerns me is that I'd like to potentially leave WSPR active overnight, but am worried that I'll generate spots with random power levels. I've not seen the power levels changing like this when I've observed the system while it is running (typically when I manually click on "TX Next").

Just wondering if this is something normal / expected or not.