Monday 10 February 2014

A Radio Free Weekend!

No chance to do any radio this weekend as was away with the XYL in North Yorkshire. Packed the Baofeng but never got chance to turn it on..

I did manage to get along to Maplins at the end of last week and grabbed some expensive N-Type connectors (as well as some other connectors, a cheap dummy load and an antenna switch!) So this evening I am hoping to sort out my Moonraker 7-element 70cm ZL-Special for the 432MHz UKAC contest tomorrow night.

I have been reading up on the ZL since I have always been a bit confused by the antenna.

The assembly instructions for the Moonraker one were very poor and the joining of the two phased elements was achieved using simple straight wire, rather than the twisted transmission line I was expecting. It has worked reasonably well as a RX antenna but I haven't used it for TX yet.

I have found a small section of ladder line from an old FM radio antenna, so will be using that now that I have more of an understanding of how it works, the front element and the larger rear element are supposed to be approx 1/8 wavelength apart (I haven't measured it yet) the two are joined using a twisted section of transmission line 1/8 wavelength in length.

There is also a trimming capacitor to help with the matching, so with this information I hope to get things tuned up nicely, the only draw back is only have RG-58 coax at the moment which isn't ideal for UHF, but it is only a 10m length and will be using proper N-Type connectors.

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