P. C. Electronics 2522 Paxson Lane Arcadia CA 91007-8537 USA
©2005
Tel:
1-626-447-4565
m-th 8am-5:30pm pst
(UTC - 8)
Tom
(W6ORG)
& Mary Ann
(WB6YSS)
24 hr FAX order line 1-626-447-0489 Email: [email protected]
Web site: http://www.hamtv.com
TC70-20Sa 70 cm ATV TRANSCEIVER
USERS MANUAL
The TC70-20Sa transceiver is designed to provide over 20 Watt p.e.p. (sync tip), continuous
duty, of AM video modulated RF in the 70 cm (420-450 MHz) Amateur band in transmit, and downconvert
the whole band to TV channel 3 (61.25 MHz) or 4 (67.25 MHz) to enable receiving on any standard
NTSC television set or VCR with a tuner.
Before transmitting, you should find out from local ATVers which two of the four common USA
frequencies - 439.25, 434.0, 427.25 or 426.25 MHz - are used in your area per the local band plan to
avoid mutual interference with other mode users. Generally, the more populated areas which have FM
voice repeaters below 444 MHz will use 434.0 MHz instead of 439.25 MHz as the primary ATV frequency
to get away from receiving interference. 426.25 MHz is the most common secondary frequency for
simplex. All four frequencies are close enough to cable channels 58 to 60 for the TV sets AFC to lock on.
However, cable TV tuners are not as sensitive as the tuneable tuner in the TC70-20Sa or TVC-4G.
421.25 MHz can only be used if there is a VSB filter in the antenna coax to remove the lower sound and
color subcarriers below the band edge at 420 MHz and therefore only used by repeater outputs.
Any licensed code free Technician class or higher Radio Amateur may operate this transmitter in
accordance with 47 CFR part 97 of the FCC Rules and Regulations. The TC70-20Sa accepts U.S.A.
standard composite video (1 volt pk-pk) from any source such as color or black and white TV cameras
or camcorders, VCRs, or computers for transmission. Audio from these sources or a low impedance
dynamic mic is also transmitted on the 4.5 MHz FM sound subcarrier. PAL video may also be used but
the sound subcarrier must be special ordered to be set for the specific frequency used - 5.5 to 6.5 MHz.
PLEASE read through this manual before plugging in any cables and attempting operation. Each
connector and control is described here to enable your proper hookup and operation. Also the unique
video practices associated with ATV and the 70 cm band are described.
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©2005