AMX TXC16 Plus Specifications download pdf (Page 53)

SG-2000 MANUAL 46

The SGC Building, 13737 S.E. 26th St. Bellevue, WA. 98005 USA

3. If an antenna coupler is mounted in the trunk of a vehicle, it will have 1 to 2 feet of

HV cable going to the antenna on the outside. With as short as a 1-foot lead wire,

and using a 9-foot antenna, this means that fully 10% of the antenna system is inside

the vehicle where it won't transmit or receive. It also creates another 10 to 100 pico

Farads of capacitance which results in more losses! With QMS, you'll pick up 3-6

dB.

4. Wire size of the antenna counts. Almost the resonant type antennas are wound

with number 22 wire. The SG-303, the antenna used with the QMS, is wound with

3 millimeter wide tape wire strap — equivalent to AWG # 4 wire. With a 100-watt

class transceiver, you'll develop 3 to 7 amps (or more) of RF on the antenna, and 7

amps through #22 wire represents major losses. The QMS with the SG-303 antenna

scores another 3-6 dB advantage.

5. The SG-303, is actually two antennas in a single casing. A single rod equivalent to

the conventional stainless steel whip element resonates at about 22 MHz; plus a

helically wound element resonates at about 10 MHz. This means that on lower

frequencies, those under 20 MHz or so, the SG-303 will vastly outperform a

conventional 9 foot whip. Chalk up several more dB for QMS.

6. Some hams use the so-called “antenna tuner” built into some radios and feed their

antennas directly with coax. The problem is that with a non-resonant antenna, a

very high SWR exists on the feedline between the radio and antenna even if you

get a low SWR reading with a built in tuner. Built-in tuners are nothing more than

trimmers. The QMS system puts a true coupler right at the antenna. When your

feedline SWR is above 4 to 1 you have effectively put 29 pico Farads per foot

capacitance to ground! That's at least 3 to 6 dB more gain for QMS!

GAIN ADVANTAGE USING QMS!

As you can see, our gain advantage of 20 dB for QMS is pretty conservative! Here's one

more thing to remember: QMS mounts without drilling any holes in your vehicle. That's a

major advantage at vehicle trade-in time. So, if you're planning to use HF while mobile,

SGC's QMS system is the best solution you'll find. Contact your SGC dealer or call SGC

direct.

11.8 Unconventional Mobile Antennas

In HF mobile work, there are as many antenna alternatives as there are experienced HF

installers.

The "J" antenna is perhaps best described as a bar rail type affair insulated from the top

of a van, truck, or other flat roofed vehicle.

1 2 ... 48 49 50 51 52 53 54 55 56 57 58 ... 241 242

No comments

AMX TXC16 Plus Specifications Page 53