Posts Tagged ‘zl-special’
I have a small Moonraker 7-element ZL-Special on the main antenna mast, purchased originally for monitoring satellites and was pressed into service for SSB when I got licensed. It has never wowed me performance wise and I have been intending to replace it for quite a while but since I only use it one day a month it hasn't been a priority. So the mast came down last night and I removed it so I can take it out with me to operate portable from some higher ground tonight.
|Using the 2m delta beam in June 2014
Last year I had a go at operating portable from the car and posted a write-up. It is my intention to repeat this exercise but with the 70cm antenna on top of my 'painters pole' mast. I have serviced the antenna and fitted a new short run of quality coax and spent a far amount of time with the AW07A analyser adjusting the antenna's tuning capacitor and have got the VSWR right down to 1.1:1 on 432.200MHz so things should be optimal.
I am looking forward to this evening, hoping it pays some dividends.
As I mentioned the 24 hour March 144/432MHz VHF Championship contest took place last weekend. I took part to give away some points just grabbing a few short sessions with the radio. I concentrated on the 2m band due to my issues on 70cm.
In my AW07A analyser review I mentioned some issues with my 2m LFA YAGI, thankfully these have been resolved. The use of some wire wool to remove some corrosion and a hacksaw to take 10mm from the long elements of the loop allowed the end elements to 'trombone' in sufficiently to get the antenna resonant and the VSWR is down to 1.2:1 on 144.300Mhz.
I only made 18 contacts, but was happy with the distances achieved with 30W, getting a lot further south than I normally do, given I am 18m ASL. There was also some local wideband noise (I captured a screenshot on the SDR) and the conditions gave some interesting fading.
|M0NRD QSO map March 144 VHF
|Noise across the band
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.