Monday, June 15, 2009

Back on 50 MHz again...

Things have been pretty quiet on the radio front recently....mainly due to a lack of interest on my part as much as anything else.

With the start of the Summer Sporadic-E season in May, I found myself listening more and more on 50 MHz but the aerial left a lot to be desired. A 145 MHz 5/8 wave magmount which acts like a loaded quarter wave on 50 MHz might be fine in an emergency but the performance is awful.

I tried tuning the HF doublet and while it was better than the magmount, it was only fair.

At this stage in the season, I decided to put up something fast in the attic and leave the outdoor work to later. My antenna of choice was a 2 element yagi, much the same as my first antenna on 50 MHz way back in 1991.

My choice was based on the following...
a) A modest bit of gain (~4dbd) with a Front to Back ratio of about 10-12 dB.
b) At the apex of the roof, it would be approx 8 metres above ground level.
c) Wide beamwidth....point it east towards Europe and forget about the west.
d) Feed point impedance close to 50 ohms so it is simple to feed with no complex matching arrangement required.
e) Permanent installation. This for me was probably the main consideration. As an indoor antenna, it is protected from the elements and the coax and elements will never corrode or break.

While an external antenna would be a better choice in terms of lower loss and less noise, at least the attic 2 element will always be there to fall back on if needs be.

It got it's first airing on the 11th of June and despite the fact that it is indoors, it seemed to perform fine. Over the space of 3 hours, I worked 54 stations in 45 locator squares. Of particular note were some of the contacts with stations in OH (Finland) at around 2,000 kms. They were probably coming in at a low angle so the 2 element may not be so bad after all.

Putting the contacts into VQLog revealed one contact was a new square for me...JP53. Other interesting contacts were with DF2UU and OH1LEU. According to VQLog, I first worked them back in 1991, a mere 18 years ago!

Also worked was DL5SBA who I worked on 10m back in 1988, a full 21 years ago!

It seems strange how out of 54 contacts, I should work stations that I had my first contact with around 20 years ago.

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