On Fri,12/16/2016 9:27 PM, Gary Smith wrote:
With the ATU in or out it gives 81W out on 160, SWR is 1.28
All other bands except 6M give around 98W, 6M gives 87W
Any ideas what might be causing the lower output on 160?
81W is 0.9 dB less than 100W; 87W is 0.6 dB less than 100W. On 6M, it's
probably a simple matter of efficiency -- power amps are slightly less
efficient on 6M than on the lower bands.
And there may be a power calibration issue. There's a procedure in the
manual for doing that.
Or even error in the power measurement itself. Few power meters are
specified for better than 5%. Bird wattmeters are specified as 5% of
full scale, and a condition of that is that the slug is in calibration.
If, for example, you're using a 250W slug, accuracy is +/- 12.5W. I use
an N8LP LP100A, which specifies 5% at any power level from 1W, and
quotes 3% typical. 5% is 0.22 dB. 3% is 0.13 dB.
Low DC voltage can also be an issue, either due to the power supply
itself or IR loss in the power cable (or even the connector(s). Use the
built-in metering function to check DC voltage with just the RX running
and keydown. Short, fat copper is your friend. :)
73, Jim K9YC
______________________________________________________________
Elecraft mailing list
Home: http://mailman.qth.net/mailman/listinfo/elecraft
Help: http://mailman.qth.net/mmfaq.htm
Post: mailto:[email protected]
This list hosted by: http://www.qsl.net
Please help support this email list: http://www.qsl.net/donate.html
Message delivered to [email protected]
