Ho una beby loop istallata al terzo piano 2,20 metri dal pavimento, il ros letto sull'ATU è sempre differente da quello sulla radio o strumento esterno.
La cosa strana è che se scrivo la frequenza sulla tastiera 2...3...4... volte l'ATU fa partire l'accordo e da sempre un valore di ros differente.
Questa mattina in 20 metri su frequenza 14074Mhz ros 1.0 oggi pomeriggio dopo aver cambiato banda torno su quella per l'FT8 in 20 metri e leggo ros 2.2 dopo svariati tentativi di accordo raggiunto 1.5 non riesco a capire dove sta il problema.....
First, the resonant frequency of the antenna is temperature dependent, especially on 20m and 17m. This is not surprising, as it is made from aluminium which has a fairly high expansion coefficient. Consequently, you will find that if you operate using FT8 or other fixed-frequency digital modes, then as the day progresses and the temperature varies, you will have to press the ENTER key to re-tune the antenna.
Second, make sure that the bolts securing the linear actuator to the plastic insulating bars are not too tight. They should not be loose, but you should be able to fairly easily turn the bolts with an Allen key. If they are too tight this increases the static friction, or 'stiction' which gives a jerky motion to the movement rather than a nice smooth action.
Third, it is useful to cycle the antenna between its fully open and fully closed positions to ensure that the grease in the linear actuator is kept soft and the actuator well lubricated. The easiest way is to use the TEST facility. Press and hold the forward slash (/) key until prompted to enter a frequency. Enter 6600 kHz. Open the antenna at high speed by holding the '9' key, at medium speed with the '8' key, and at slow speed with the '7' key. Drive the antenna out until motor cut-off. Then drive the antenna in at high speed with the '3' key, at medium speed with the '2' key or at low speed with the '1' key. Drive it into the inner electrical limit. Then, open the antenna slightly with the 7, 8, or 9 key. Exit the TEST mode by pressing the BACKSPACE <- key, and press the ENTER key to re-tune the antenna.
It is not unusual to find that the SWR indicated on the Ciro-Mazzoni controller and the SWR indicated on your transceiver differ. In my experience, the SWR indicated on several controllers that I use tends to be somewhat pessimistic, that is, it tends to read slightly high. Since the controller is only seeking the minimum SWR this difference is not important.
I hope that these notes are of some help.