So, now you have your screwdriver antenna installed, on you vehicle, and it's time to tune...

• Automatic or semi auto:
• I'll add this later...

• Manual/ Remote types (uses an up/down switch):
• Read the antennas manufactures directions first (use this page as an extra aid)...
• Read the radio manufactures directions first on how to operate mobile radio (use this page as an extra aid)...
• Make sure to connect the screwdriver antenna motor switch, as so, to make, up is up, and down is down...

• Tune first without transmitting!
• Tune for maximum band noise on SSB or AM. SSB seems to better. Use some thought hear:
• Turn off the attenuator (ATT), and or the NB, or switch the AGC to fast, lastly turn on the preamp (IPO).
• If your tuning for 80M (3800 kHz), and the antenna is, all the way down, (no terns showing) then it will need to go up, quite ways (will take 30 seconds to a minute or more).
• Typically most DK-3 type antennas, with about a 4-6 Ft whip, will need to be, almost all the way out (about a foot of coil exposed).
• With a, 8-9 Ft, or a 4-6 Ft whip, with a Capacity hat, expect, about half way out
• There is better performance using a, Cap Hat, because there is less coil needed to  resident the same frequency. Of all the losses, this is most easy to fix, coil losses are the easiest to fix (bigger wire, proper turns per inch (ratio), Coil diameter (Antenna Q).
• If you go up or down, to far, then you will hear, the antenna making a clicking noise (not over the radio). Stop. You've gone too far, go back the other way.
• May require temporally stopping the antenna (screwdriver) motor, to listen.
• Palls it, on and off.
• As the band noise comes up, and then starts to decline (the noise level). Stop, just as the noise starts to decline.
• Using DTMF, or by switching to AM or CW, transmit, while going back tords where you herd the maximum noise (back down).
• Watch the SWR, Tx power, or with a RF Field strength meter.
• Usually SWR under 2.0, is minimally, ok. 1.5 is good enough...
• Dip the SWR for minimum. Typically, 1.2, or so.
• Peak the RF PO, maximum field strength. (Note: RF PO, will peak over a larger range as SWR's of, 2.0 usually, will yield 100% output (100W (Example: Yaesu FT-100d).
• If you using a ICOM 706, the SWR needs to be less than 1.3:1 (It will reduce the RF PO, significantly, above 1.5 SWR! (1.5@75W, 1.8@50W, 2.0@25W)
• Also, Some older radios can't handle SWR over 2.0, read your manual.
• Your done. Switch back to your mode of operation...
• Band switches. If you on 80M, and you want to go to 20M, then tune the antenna to shorter.
• Repeat at, "Tune first without transmitting!"
• Forget where your antenna was tuned last?
• First, I'd think, the band you find your radio on, is the tuned up band.
• Switch through the bands. The one with the most noise, is the most likely, the one tuned for.
• Also, You can add some visual aides to this process. Mark the antenna where the antenna cover comes to with colored tape (antenna is almost all the way in for 10-20M, is most of the way out for 40-80M). Or use a "Sharpie"...
• More ideas to come...

 

 
 



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