Link HD System Manual
Document # -HD System Man Iss 1.1 Issue 1.1 06/11/2007
Page 13 of 31
2.3 L3020 Down Converter
The L3020 is supplied with a L3520, +3dBi vertically polarised omni-directional antenna; alternatively it may be used with
the L3480, 6dBi vertically polarised 180° directional antenna which is available from Link Research Ltd..
The down converter is supplied with a universal bracket for pole mounting. For temporary installations, tie wraps may be
used; for permanent installation U-bolts should be used.
Whichever method of mounting is used, it must be capable of supporting the weight of the L3020 and the coaxial down
lead.
No other connections are required as the unit is powered from the receiver via the RF down lead.
2.3.1 Filter Selection
The L3020 is supplied with an add-on filter with a passband of 1.95GHz to 2.7GHz thus rejecting all out-of-band unwanted
signals. Alternative narrow band filters can be used with the L3020 making it even more frequency selective.
L3030 1.95GHz to 2.7GHz (supplied as standard)
L3033 2.2GHz to 2.3GHz
L3034 2.3GHz to 2.4GHz
L3037 2.5GHz to 2.7GHz
The L3050 is used for 3.4GHz to 3.58GHz band in conjunction with the L3060 filter unit.
Changing the filter requires the removal of four screws. This is detailed in Section 4.3 of this manual.
2.3.2 Cable types
Ideally the receive antenna should be mounted directly on the down converter. Where this is not possible, the shortest
length of cable should be used to minimise the losses. A low loss heliax such as Andrew type LDF450 should be used.
This is a ½” thick cable using foam dielectric and solid copper outer. Other similar low loss thick cable can be used.
For the cable between the down converter and the receiver, a low loss foam dielectric such as Commscope RG59 or RG11
75 cable should be used. In addition to being low loss, these cables have an extra layer of screening making them more
robust and less susceptible to interference. Using these cables will allow a 100 metre run with RG59 or 150 metres with
RG11. For details of Commscope cables and local distributors visit www.commscope.com
2.3.3 Controls and Monitoring
There are no operators controls fitted to the L3020 Down Converter.
An LED on the front of the unit indicates the status.
Colour Function
Red Power OK
No communications to the filter unit
Amber Power OK
Communications to the filter unit ok
Off No power present.
Changeable Filter
block
Down Converter
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