Friday, January 20, 2017
EFHW antenna for 40-10m qrp
I had a BN43-202 core in stock and decided to try to create a small QRP EFHW transformer from 7 - 29 MHz. As you can see in the plot the swr is verry flat from 40-10m so a capacitor at the input is not needed. A 3300 Ohm resister to ground was used for the plot. With just 20.3m wire this makes a nice 40-10m antenna. You can also use the 34uH coil of the endfed down this blog to create a compact 3 band atenna of just 12m long. 10 Watts PEP is the max. power here. Be carefull, each pass is 1 turn here. A test with 2 transformers back to back showed a power loss of about 18% on 20m.
Geplaatst door PD7MAA op 3:25 PM