mobile question

[bluestallion]

Im using a 102 whip with a ah-4 tuner. it seems to do pretty good for what it is. I have a 40m hamstick that im wondering if can use it to help improve my 40m signal, but can i use it on 20m also? If i were to get a 75m hamstick could i also do the same thing, use it on 75, 40 and 20m?

 

[M0GVZ]

If you try to use any hamstick on a band it wasn't intended for with any power you'll likely fry the matching section.

What is important for efficiency on a mobile antenna is the longest whip you can get. I changed the stock short whip on my Little Tarheel II for a 72" one and the improvement was like running a linear but as it is reciprocal, receive was massively improved too.

The ERP of your AH4 tuner with 102" whip will be more than the 40m or 75m hamstick. Stick with what you've got and make sure you've got the best bonding you can. Bond the tailgate to the body, the doors and hood to the body and the body to the chassis if it has one.

KØBG.COM has a lot of useful advice.

 

[Captain Kilowatt]

I do not recommend using a Hamstick on another band it was not designed for either. I have been down that road before as well......no pun intended. I have used Hamsticks on 20 and 75m as well as a 102 whip fed with an auto-tuner. IMO I had better results on 75m with the hamstick with several contacts into the midwest, southern USA and western Europe with just 100 watts while mobile. Although the antenna had a VERY narrow bandwidth on 75m (about 25 KHz) it seemed more efficient than the 102 and tuner combo. I did have the antenna/auto tuner combo mounted as it should be with a HEAVY short strap about 8 inches long between the tuner and the feedpoint to minimize losses. On 20m the Hamstick worked very well as did the 102/tuner combo. On 15m I used a homebrew antenna about 116 inches long with the bottom half made from coaxial braid helically wound around a 1/2 inch solid fiberglass rod and sealed with heatshrink tubing and topped with a long stainless whip. This antenna is self resonant on 15m and was tuned with the auto tuner to cover 12m,17m and sometimes 20m. No worries about burning out the antenna coil as the RG8 braid will take whatever I can feed it with.

 

[W5LZ]

Quite a few years ago I used a Kenwood HF antenna mobile. It had a common bottom section and various top sections for each band. The 40 meter set up was usable on 20 meters, not the best in the world, but usable. Used a TS-440SAT at 100 watts(?) and had no matching problems with it. Eventually destroyed the thing, a fiberglass antenna doesn't hold up well if it's used in this particular area (trees/stuff).
Also had a friend who used the tuner and 102" whip type set up. Worked okay on the higher HF bands, was terrible on the lower ones. He tried various whip alternatives, even made one. Same results, not adequate in most cases.
What it amounts to is that no matter which tuner you use, it will only be capable of so much with whatever you use for the radiator. It may radiate, but it may not radiate worth a hoot, you know? You can only 'shrink' an antenna so much before it isn't worth the effort. Especially for the lower HF bands, if it ain't big and ugly it probably isn't going to work very well (no matter how you load the thing).
Nothing 'new' in this, still no 'miracle antennas', just something to keep in mind.
- 'Doc