Atlas 210x, Installation, Operation And Maintenance Manual

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2-10. 200-PS PORTABLE AC SUPPLY. The model 200-PS AC Supply is designed for portable and utility service
where the weight and size of the deluxe AC console is not desired. It's compact size and lightweight make it ideal
for the traveler, and yet it will do a completely adequate job in full time duty at the home station. It has a slightly
smaller power transformer than the AC console, which reduces D.C. input power about 5 percent, but peak power
with voice modulation is the same as with the larger transformer. Also, the 200-PS does not contain a speaker, so
the one built into the transceiver is used. The 200-PS operates on either 110 volts AC or 220 volts AC, selected by
changing fuses.
It is anticipated that a plastic or simulated leather carrying case will be available from Atlas Radio for the 200-PS
supply as well as for the transceiver in the near future.
2-11. TRANSMISSION LINE IMPEDANCE MATCHING. Proper impedance match between the coaxial feedline
and the antenna system is considerably more important with the broadbanded solid state amplifier than with tube
type transmitters, which generally have a Pi-type matching network. The SWR should be as low as it can be in
order to permit full power operation. As SWR increases, power output from the Atlas transceiver decreases
approximately as indicated in the following table.
TABLE 2-1. SWR VERSUS OUTPUT
SWR APPROXIMATE
OUTPUT NOTE
1.0 100 watts High SWR will not damage the
1.1 98 watts Atlas transceiver. You may feel
1.2 95 watts free to operate regardless of the
1.3 90 watts SWR. Only power input and
1.5 80 watts output will suffer. Reflected
2.0 50 watts voltage will not cause damage.
3.0 20 watts
2-12. AMMETER READINGS. The ammeter on the Atlas transceiver provides an excellent indicator of
impedance match. In CW transmit mode, the Mic. Gain control becomes the Carrier Insertion control. With a
close match you will be able to run the ammeter up to 12 amps or more (with supply voltage of 13.6 VDC or
117/230 VAC).
2-13. INFINITE SWR PROTECTION. The Atlas transceiver has a built-in reflecto-meter which automatically
reduces transmitter drive as SWR increases. This makes the power transistors nearly immune to damage from
mismatched loads.
2-14. SWR MEASUREMENTS. A bridge for measuring Standing Wave Ratio (SWR) is very useful and
strongly recommended for checking impedance match. Use the following procedures.
(a) Switch the bridge to "Forward" or "Sensitivity position.
(b)
Set the sensitivity control on the bridge to maximum clockwise position.
(c) Set Mic. Gain on Atlas transceiver to minimum.
(d) Set the transceiver Function Switch to CW mode.
Advance Mic. Gain until meter on bridge reads just full scale. (Mic. Gain is Carrier Insertion control in CW
mode).
Switch bridge to "SWR" or "Reflected" position for the SWR reading.
Tune the transceiver up and down in frequency until you locate minimum SWR. This will indicate the
resonant frequency of the antenna, and also the SWR at that frequency.
Switch the transceiver back to REC. mode. See Caution note, next page.
(e)
(f)
(g)
(h)