SGC Smartuner SG-231 Technical Information download pdf (Page 21)

Mailing: PO Box 3526, Bellevue, WA 98009

Shipping: 13737 SE 26th St., Bellevue, WA 98005

Toll-Free: 800-259-7331 • Phone 425-746-6310 • Fax: 425-746-6384

www.sgcworld.com • Email: sgc@sgcworld.com

Unfortunately, when you use a can-type dummy load, you can't see

"what's happening" with your transmitter. In this case, you can use a

light-bulb dummy load to test your transmitter. Here, the light bulb is

directly connected to the output of the transmitter and it dissipates the

RF energy as light. The light bulb dummy load is more useful than the

oil-can type because you can guess how much power is being output,

you can see the voice modulate the SSB (the light will flicker with

your voice peaks), and you can tune the transmitter for maximum out-

put (if the transmitter is an older model that requires tuning).

Before building or using the light-bulb dummy load, remember that

these models typically don't dissipate the transmitter's output as well

as an oil-can dummy load. The result is that RF will "leak" out; we

have heard a few stories of amateurs who were heard around town

while operating their transmitters into a light-bulb dummy load. If you

use this system, make sure that you test the equipment on a clear,

harmless frequency (NEVER test with the transmitter set on an emer-

gency frequency, such as 2182 KHz).

SGC recommends that you build the light-bulb dummy load with the

following parts (although we have made one with an old light fixture

and a makeshift ver-

sion with just alliga-

tor clip leads and a

light bulb):

* AC socket to cable

with a PL-259 con-

nector (for trans-

ceiver)

* AC socket to cable

with alligator clips

(needed with coupler)

* Light bulb to AC

adapter

* 75 to 125 watt

light bulb, 120 to

220 VAC

Radio

RF IN-OUT

RF GND

Radio

RF IN-OUT

RF GND

Antenna Coupler

Antenna Jack

GND

SG-239 Manual

page 21

Wednesday, October 17, 2001 08:31

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