Saturday, April 1, 2017


Picked up a little 2 Watt HF Linear amp on Ebay.    Wanted to get to +33 dbm instead of the +23 dbm I am currently WSPering at.

Looked at the WSPRlite power op at the various settings

30 Meters
Desired OP                  Measured OP               Delta
200 mw                   +23 dbm /200 mw               0 db
100 mw                   +20.8 dbm /120 mw       +0.8 db
  50 mw                   +18.3 dbm/67mw           +0.7 db
  10 mw                   +12.2 dbm/16mw           +2.2 db
    5 mw                   +9.8 dbm/9mw               +2.8 db

80 Meters
Desired OP                  Measured OP               Delta
200 mw                     +24 dbm/251 mw           +1 db
100 mw                     +22 dbm/158 mw           +2 db
  50 mw                     +19 dbm/80 mw             +2 db
  10 mw                     +13 dbm/19 mw             +3 db
    5 mw                     +10dbm/10 mw              +3 db

So the results were tightener then I was expecting!  

I needed to know the levels because I bought this little 2 Watt Amp...

The manufacturer said 1mw drive would give you a +33 dbm OP.   When I tested it it need allot less drive.   Used the 80m beacon from the WSPRlite set to 5mw OP (  actually 10mw ).  To get +31 dbm out of the amp I was driving it with a 29 db pad installed whic turns out to be a -19dm drive level yielding a +31 dbm op ...50 db gain!  Driving it any harder just created intermods and no more power op.  

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