Monday, 7 January 2013

Attic Doublet revisited

Just a quick post about my loaded doublet in the attic, fed into a remote smartuner.
This has proved quite useful and much better than expected. This I put down in part to some excellent choking on the coax feed-line from the smartuner back to the shack. This seems to keep the noise down a little and the use of electric fence insulators helps too rather than tacking directly to the timbers.
No this is not a DX aerial but a compromise solution where large plots are not available or stealth is desirable or enforced.
Downside is I would only run QRP 5watts due to proximity to household wiring and RF exposure.
This indoor aerial is only about 1-2s points down on my outdoor wire described earlier, though the latter is quieter.
The Smartuner could be omitted  and the aerial fed with coax for dualband 40/20m operation or fed into the shack via 300ohm feeder into a z-match or similar.
To recap: 40m/20m loaded doublet aprox 40ft long , inverted V and dog legged to fit in small attic.
Works 40m-10m with smartuner :-)

Details of choke Balun G3SEK in Practice Website

Smartuner fed with 300ohm below doublet

choke balun and DC control line.

40m loading coil dog leged

300ohm feedpoint

electric fence insulator

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