mobile antenna & auto tuner?

[KD2GOE]

I lot my mined and according yo my wife and installed a 3/8-24 stud mount on to my trunk lid. Where ill be attaching a 102 whip or a ham stick... I have seen a few pics of people just running a jumper wire right from he tuner to the antenna instead of coax to the antenna.. i am guessing that just running the 6" or less jumper wire helps in tuning the 102 whip with out having to just for the 50 ohm cable in the way? right now my coax is 3' but i can move the tuner and mount it right to the under side of the trunk lid


I may not even go with a ham stick i may cut down the 102" whip to 90 Or 80" and make swap out loading coils.. or a adjustable loading coil like a manual screwdriver.... hmmm brainstorming...

 

[w9cll]

Read this site thoroughly - http://www.k0bg.com/

 

[KD2GOE]

Read this site thoroughly - http://www.k0bg.com/

thanks i am reading though it.

 

[Captain Kilowatt]

Using even a short length of caax between the tuner and antenna can yield BIG losses. I ran an auto tuner and 9 foot antenna and had about six inches of heavy coax braid as a connection. It worked good.

 

[The DB]

A friend of mine used an MFJ auto tuner into a 102" whip plus spring with about a foot of LMR-400 connecting the antenna to the tuner. It worked well, he was able to get between 10 and 40 meters with that setup.


The DB

 

[Captain Kilowatt]

The issue IIRC is the capacitance of the coax appearing as a shunt capacitor and depending on the low impedance and voltages present can reduce the signal greatly.

 

[KD2GOE]

The issue IIRC is the capacitance of the coax appearing as a shunt capacitor and depending on the low impedance and voltages present can reduce the signal greatly.

that's kind of what i was thinking..

So when the antenna is way out of the normal operating freq the impedance of the antenna is way out of spec and the capacitance of the coax absorbs the energy that would have been radiated out?

 

[Captain Kilowatt]

Well yeah...kinda. The capacitive reactance in parallel with the antenna impedance can cause the cap to sbunt most of the RF to ground depending on the actual impedance of the antenna at the operating frequency.

 

[fourstringburn]

Ever consider using a automatic screwdriver antenna? With a press of a switch you can easily tune to a frequency you desire.

The Little Tarheel models weighs less than 2 lbs. The HP 500 watt version covers 10- 40 meters while the 200 watt version covers 6 -80 meters. Without going into detail, the HP version is the better one even though band coverage is less.

These are easy to install with just a supplied switch and antenna control cable and they mount right on a 3/8 x 24 stud.

http://www.tarheelantennas.com/littletarheel_hp

 

[KD2GOE]

Ever consider using a automatic screwdriver antenna? With a press of a switch you can easily tune to a frequency you desire.

The Little Tarheel models weighs less than 2 lbs. The HP 500 watt version covers 10- 40 meters while the 200 watt version covers 6 -80 meters. Without going into detail, the HP version is the better one even though band coverage is less.

These are easy to install with just a supplied switch and antenna control cable and they mount right on a 3/8 x 24 stud.

http://www.tarheelantennas.com/littletarheel_hp

yes but i just cant spend that kind of cash.... maybe some day..

 

[fourstringburn]

Understandable...Here is a good link to read that W9CLL suggested. I still use this website for my mobile HF information from time to time.

This link is from K0BG website regarding the use of 102 in. whips and tuners (couplers as Alan refers to them).

On K0BG's home page he has his email address where you can correspond with him directly if you have any questions for him. He is pretty good at getting back to you fairly quickly.

http://www.k0bg.com/couplers.html

 

[KD2GOE]

Ok cool looks like a have most if not all the info i need ill report back in the spribg when i get every thing setup..
Thanks