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The 80m Coaxial L with mods for 160m and WARC.
  Another black box?

Sometimes, life on the airwaves starts out as a black box. This one is a Hills OH1 - Outdoor Housing. A good starting point for some 'lectronics that has to be put out in the weather. The antenna coax leaves the box and goes off to the right. The brown cable is the remote relay control cable and the black coax on the left goes to the transmitter.
 
 
  So, what's in the box, then?

Ah! The 'lectronics. With no relays active, the transmitter is fed directly to the coaxial 1/4 wave antenna (80m). The large inductor is switched in for resonance on 160m. Additional impedance matching transformers (hidden behind the large inductor)are used for the other WARC frequencies. This prototype pcb was designed and built by Paul VK5AB. (I just installed it in the box!) *** Contact Paul for updated details and information on this project via email: vk5ab@wia.org.au
 
 
  Top side view

This view shows the relays and the required earth stake. I mounted the OH1 with it's supplied bracket with two stainless nuts and bolts to the earth stake. (The coiled earth wire is not used for rf earthing!)
 
 
80m inv L swr   Typical VSWR values

80 metres:
 
3.50 MHz - 1.5:1
3.55 MHz - 1.3:1
3.60 MHz - 1.15:1
3.65 MHz - 1.15:1
3.70 MHz - 1.35:1
3.75 MHz - 1.6:1
3.80 MHz - 2.0:1
 
 
30m swr  

30 metres:
 
10.10 MHz - 1.4:1
10.13 MHz - 1.4:1
10.15 MHz - 1.4:1
 
 
17m swr  

17 metres:
 
18.07 MHz - 1.2:1
18.12 MHz - 1.2:1
18.17 MHz - 1.2:1
 
 
17m swr  

12 metres:
 
24.89 MHz - 1.1:1
24.94 MHz - 1.1:1
24.99 MHz - 1.1:1
 
       
    2006-2009 S.Spirat 
Another SPIRAT initiative