Cutting a SIRIO 26.5 MHz - 30 MHz 4 Element Yagi ANTENNA

[Bombardier]

Hello,will try to make this short. I love 10 Meter,and I also use the 27MHz CB, 11 Meter band also. This antenna can be cut to get a center frequency,as out out the box it set for 26.5 MHz, uncut. My question is I have a Yaesu FT-991A with a built in Antenna Tuner, and I dont want to molest the Antenna and cut for a frequency as I will me using the 10 and 11 meter bands. Does it make sense to leave the Antenna unmolested and use the Antenna Tuner to tune the Antenna, as im understanding this is what the tuner is for, as there is really not much of a large area or frequency to tune. Thing is,after its cut, not fixing the Antenna to put back to the original out of box setting.
Main question is,,,,,,,should I just leave it unmolested and use the built in Antenna Tuner as I would think it would tune, as it works on my Vertical A-99 with the ground plane kit, with no problems, tunes very well. Once cut, thats it. As long as i tune the Gamma Match for low SWR, while using the Antenna Tuner I am assuming, new messing with 4 ellement Beams. Any suggestions and directions if left ucut would be SO MUCH APPRECIATED, as I would tune it on a pole in a bucket on the ground first before putting up on my tower,its a tilt tower, so a bit freaky and the anxiety of doing this can really get to you. Any ideas, cut or no cut. Thanks,any suggestions wil help. Enjoy your day,and stay cool. 73's,,,Mark KB9GTB

 

[sp5it]

You must change element spacing too. Shortening elements is not enough.
If antenna is tuned to 26MHz with antenna tuner on 10m it will perform poor and vice versa. Antenna tuner protect radio finals, nothing else.
Mike

 

[Blackcat630]

If it were me I would split the difference. If I wanted to use the entire cb band and most popular voice portion of 10 do a little math. 28.500-26.965= 1.535 mhz of bandwidth is really what you require. Divide that in half and either add that to 26.965 or subtract it from 28.500. 1.535÷2= 0.7675 mhz. 26.965+.7675= 27.7325 would be where I would tune for lowest swr. In theory this would give you equal bandwidth in either direction... An antenna analyzer is your friend for these jobs. I don't know the bandwidth of this antenna but if it gets sketchy on the outer limits you could then use the tuner as a last resort. Tuners will make the radio happy but at the cost of antenna efficiency. Lack of resonance= loss of efficiency= loss of performance...

I'm not familiar with the design of the sirio but if the elements telescope inside one another I would definitely tune this way before cutting.

Tune in a wide open space. No medal around. Some guys like to sit the beam straight up at the sky on the reflector and tune.. I usually just put it on a 8 ft piece of pipe in the the ground a foot or so. Also once tuned on the ground, resonant freq might drop slightly once erected on the tower...