Change of Aerial and repainting mobile mount

A couple of days ago I received my new Diamond NR-790 Mobile aerial (Antenna for my USA readers) to replace the one I borrowed from my friend John (M1FEL).

Diamond NR-790 on car

You can see that this is the Mark II model ~ now using two heavy-weight closed coils.  The 2m band (145 MHz) sees the aerial as a 6/8th wave device (giving 3.7 dBi @ maximum of 300W power out of the radio) whilst the 70cms band (433 MHz) identifies the aerial as 3*5/8th wave device (giving 6.4 dBi @ maximum of 250W power out of the radio).  The aerial is able to handle more than I require, but it is substantially made and has already given fantastic results (see below).

The base below the black 'collar' is much improved

The photo above shows the lower part of the aerial.  Between the mount, i.e. bottom of the aerial, and the first black collar is an important part of this aerial's success: it is a built-in 'ground-plane' ~ ensuring that the aerial is really efficient when it comes to 'matching' the frequency in use.  This section is much larger than the Mark I version ~ probably to handle the extra power ~ but also because the matching has been improved.  The aerial performs as least as well as the Mark I, maybe better?

Painted aerial mount

If you look at an earlier post, you can see that the aerial mount had to be modified ~ leaving it a mixture of black & silver, with a touch of bronze!  I'm not usually worried about looks but, on this occasion, I thought I would paint it all black, using enamel bought from a local shop.

Needless to say, they did not have black!  Henry Ford would be turning in his grave, I thought, but then I saw a pot of red enamel.  The rest you can see for yourself!  I think it looks better ~ even though I have to clean the red enamel off the wire later!

As for the efficiency of the aerial?  Using 5 Watts of power from the radio, I can talk for miles on 2m (145MHz band) ~ not using a repeater I quickly add ~ and I had a similar reaction when using 5W on 70cms (433MHz band), despite going into dips, under tunnels of trees, etc.  Quite amazing!

John (M1FEL) and I will continue to carry out tests on the efficiency of the aerial over the next few days.  Our test for tomorrow will be to see how far we can work each other using 5W on 433.375MHz.  

More anon............ so watch this space!