Today we have a look at the C42 configuration and it turns out to be a simple fix to get a near perfect antenna setup. I would expect there are different aerials installed over time on the C42 range and possibly different ground planes. Until I have seen more examples and tested them I will not know.
Here are the pictures of the outside and inside of the antenna installation, so you can compare it to your own C42.
The initial readings were actually not too bad and the general comment of the operator was, “it works fine so there is nothing wrong with it!”.
What a great SWR reading at 122 Mhz with a 1.19 SWR. Not so good on the 78 ohms though but all together the operators comment was justified. It works !
The mid range SWR 1.77 which is acceptable and in the yellow but still too close to the borderline mid frequency for my liking.
Removing the old aerial which has been in place for years and aerial inspection has turned out to be quite a drama. If you try to unscrew the aerial it breaks the coax signal wire solder joint below the deck. So as a C42 owner , if you have ever removed the rear deck this could be a hidden problem with poor reception. This needs to be re-soldered if you haven’t found that out yet!
To take it all apart and put back together you need to use a pair of pliers and grip the hidden shaft. The rubber covering needs to be raised so you can get the grip of the narrow pliers (I used my faithful MullGrip) in the right place.
Obviously this does not need to be done as with most aerials an Allen screw that holds the piano wire in place is easily accessible. I wanted to have a good look and check the integrity of the seating of the ground plane and the aerial’s tightness of fit.
Now for the chop, a conservative 581mm with the rod removed, using the Allen key. Luckily I did not remove more and go for the 550mm that would have been a disaster I think! You will need a hacksaw as the piano wire is pretty tough.
Look now at what an aerial we have!!
A bit wavy and this is the second reading but it was shoved up against the dashboard and in the hangar. But LOOK at that SWR 1.01. cannot be improved on and this aerial is doing it’s job perfectly !! Or nearly (more on that later)
In the green and bang on the number. I cannot improve that. What a stroke of luck on the first cut and centre frequency.
Perfectly balanced 51.1 ohms. Not sure I want to mess with that but soooo tempting to get it to 50 ohms. Ask the guys in the know and they will say leave it alone…
Sooo tempting ! Showing SWR of 1.03 on the SWR reading but that fluctuates slightly whilst it reads but I was so excited and just hit the button.
*GOLDEN NUGGET* Dropping the ohms down from 78 to 51 decreases the load in the radio amplifier thus less power consumption.
Why is that important? Your radio works efficiently with less rouge energies flying around and therefore less noise. Strength five, quiet and clear with smooth running is what we are after.
Now we just need to flatten that SWR curve with a Balun to get all our frequencies efficient and we are there, as far as the aerial is concerned. More on that in the Balun Adventure!
To conclude, the only thing that has not been adjusted is that the aerial dougnut is not exactly level to the horizon but we can live with that for now. It would mean replacing the ground plane and realigning the aerial to make it perfect.
Have a nice day because mine has been as you can see.