User's Manual

1616
- improve the RF grounding system: use the shortest and widest possible metal strips for the
connections to ground and between the different gear in the shack; connect one or more
counterpoises (sized for the problematic band) to the feeder shield at the point, where it enters
the building, and the same point - with the possibly shortest and widest connections - to the
grounding system: this is a very efcient measure, in particular if the shack is located on a high
oor above ground;
- to reduce the RF impedance of the grounding connections sheet metal stripes instead of exible
braids are preferred;
- thread ferrite beads or snap-in ferrites with medium permeability (800-4000) over the power
cord, the feeder and the signal cables leading to the affected devices (TV etc); besides the
size, consider the frequency range in which the offered ferrites are effective – normally they
are optimized for suppression of interferences on HF (with larger permeability), with medium
permeability for HF-VHF or with low permeability - only the VHF range. The latter are ineffective
for HF;
- whenever possible use shielded cables and ground their shields at both ends;
- the addition of even quite simple low pass L/C or R/C lters directly to the disturbed inputs or
outputs of the devices is very effective, provided it is practically applicable.
Last but not least, bear in mind that the benet of the above measures is two-fold. Firstly - they reduce
the interferences from your transmissions to the ambient environment and secondly - they reduce the
background noise oor for your reception. Practically, with no great efforts, implementing the above
measures, you can reduce the background noise oor with one or more S-units across the different
bands. This will allow you not to miss weaker stations, which will hear you because of your increased
transmission power.
4. AMPLIFIER OPERATION
4-1. Change of modes RX/TX and Operate/Stand-by; AUTO OPERATE
option
a) In Stand-by mode, as well as in the unpowered state, receiving and transmitting with the
transceiver is done via RF bypass between RF INPUT and RF OUTPUT of the amplier.
In Standby, the transceiver’s RF power is not amplied, the control KEY-IN input does
not affect the operation, and the KEY-OUT output (S. 2-3(c)) follows the state of the KEY-
IN input unconditionally. The bands cannot be changed neither manually nor by CAT or
remotely.
b) In Operate mode the receive-transmit (RX/TX) direction is controlled by the KEY-IN input:
- at open KEY-IN (Operate/RX mode), the transceiver receives the signals from the antenna
through the same RF by-pass path between RF INPUT and RF OUTPUT as with amplier
turned off or in Stand-by mode;
- at grounded KEY-IN ((Operate/TX mode) the RF drive is amplied and fed to the antenna
through the RF OUTPUT connector.