Sunday, March 14, 2010

Mini Whip

Not a great story here, just found some time ago this project on the "net" and decided to give it a go. Since I am also making some tests on a homebrew Navtex receiver this should be the ideal antenna to match it.

The crappy photos:

I used the schematic from:

The top enclousure is from small plastic bottle, the main mast is from electrical tubing conduit (VD32 local reference)
and the only changes were:
- The right most 560 cap was replaced by an 470, so as one of the dc coupling caps.
- J301 whas replaced by an BF245
- 2N5109 replaced by an 2N2219
- No 10uH coil (direct connection)
- Replaced the 470uH rf chokes by 120uH (rougthly measured)
- Didn't used the fuse or the reverse polarity protection diode.... I know what I am doing so don't try this at home!
- Dimensions on the caption area are: 30 by 45mm

I was a little skeptical on this "antenna" but from the first tests I made, it works (tested on 518, 590Khz, 10.100 Mhz and 14Mhz band), at least with some moderate strength signals. I have to make an antenna switch to make some more tests, but for now given the size of the element, it's not a bad solution for those who are tight on space.

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