Let me introduce myself a little bit first.
My name is Fred Koch, 61 years young, and radio-amateur since the 1980's. Started my career as a Radio-Electronic Officer in the merchant marine so i should be aware of the theory of antenna's and tuning, however this was 40 years ago and i have not been very active in the hobby so my knowledge has faded a lot i notice.
But recently picked up the hobby again and in the weekend of November 9/10 2019 i have installed a HF9V into the ditch behind my house and tried to tune it.
The antenna is installed into the ditch, and the ditch holds about 1 M water depth. I first drove a 3,5 M pole into the earth and then mounted the base of the HF9V (Pole A) so it is about 40 cm above the water level. (see pictures in the album).
Note that the ditch is not a salt water ditch, however from reading on the internet, i have found several posting showing good results putting the HF9V up this way without using radials.
As a ex R/O i will be using CW only (with perhaps an incidental exception for SSB) so i am aiming to have the best SWR around the lower portion of the bands.
Assembly of the HF9V was feasible, however i do recognize that the instructions could be improved here and there but i think i got it right in the end.
And then the tuning begins.
I have a Mini60S as antenna analyzer and there are some strange results i would like your thoughts about. (see picture in my album where i uploaded the outcome of the scans i did)
To start from lowest to highest band
6 M: Min SWR (1,49) at 48900.. This weekend the dip was properly at 50.000 so it seems i need to tune the 6M wire a little again but overall this seems like an acceptable SWR graph
10M: Min SWR (1,41) at 27850 and overall very flat. Perfect (see Improved 10M scan)
12 M: Min SWR (2,64) at 26500. Way off. This is with 12M coil fully compressed (see pictures) as per initial tuning instructions. However when extending the 12 M coil nothing changes.
15M: Min SWR (1,45) at 20975 with enough bandwith so the 28.000 -28.100 is workable. Fine with me
17M:: MIn SWR (1,33) at 18020. could shift it a little to make lowest swr at 18080.for the moment fIne with me. Note picture 17M scan second The first shows a different result. MIni60S reliable???
20M: Min SWR (1,39) at 14010. Fine with me
30 M: SWR of 2,6 around 10.100.. Strange graph with second dip. For now workable. But what does it tell?
40 M: Two scans that both are strange. One with no dip at all (second 40M) and the first with two real sharp dips at 6650 and 6750. This important band is unworkable. This is my main concern as i want to be able to work properly on 40 M
80 M: Min Swr (1,33) at 3560. Should be shifted a little bit to the left (center frequency of 3520). Adjusting the 80M coil should achieve this.
I am very interested to better understand the complete lack of a reliable SWR graph on 40M. Looks as if something is not completly right there that is beyond tuning.
Next is the 12 M.
Note: I have not yet adjusted the base coil Q for an even lower SWR on 80M.
Looking forward to your thoughts on this.