demi 222-28 Manual

22_____ MHz Transverter, __________ MHz IF, S/N__________
Power Out:
Noise Figure and Gain:
DC Power Requirement:
IF Option:
IF Drive Level Maximum:
Keying Option:
Aux. Connection Output Option:
Antenna Option:
External preamplifier option:
Operational Overview:
The DEM 222-28 is a 222 MHz to 28 MHz transmit and receive converter. It will operate
with most High Frequency transceivers that are available on the market today. The 222-28 has a
linear output power of approximately 25 watts. At full compression, the output power may reach 35
watts, but would be recommended for CW or FM operation only. On the receive side, a GaAs-FET
preamplifier, a high level mixer (+17 dBm Local Oscillator), and a 3 chamber helical filter provide a
sensitive, yet over-load proof front end with superior out of band rejection. The DEM 222-28 has a
built in transmit / receive relay with provisions for external switching so that adding a high power
amplifier to your 222 MHz system is easy. Options have been provided for a key line input of PTT
Low (ground) or PTT High (+Voltage). Auxiliary contacts are included for either transmit or receive
with a common line for many applications. The 28 MHz IF levels are adjustable on both transmit
and receive and have a dynamic range of approximately 25dB. This is very useful for adjusting
your maximum output power and setting the "S" meter level on your IF receiver. IF connections
are via BNC connectors. The control, power, and auxiliary connections are via RCA jacks, and the
222 MHz connectors are BNC, UHF or Type 'N' (users choice). The 222-28 is housed in a 7.4" x
4.7" x 2.2" aluminum die cast enclosure with an external 7" x 4" x 3/4" heat sink to provide cool
operation under any condition.
This transverter, when assembled, has your requested options installed and will be
configured to your transceivers specifications. It is important to fully understand the functions of
your transceiver before interfacing the transverter. Please review your owners manual for any
details regarding transverter operation. If necessary, you may consult us regarding interfacing.
We have not interfaced every transceiver on the market, but could help you in making the correct
decision regarding yours.
/Built/222-28.doc
DEM Part Number 222-28
25 W linear, 35 watts maximum; adjustable
0.8dB nominal, +17dB nominal (25 adjustable IF Attenuator)
12 - 15.5 VDC, 13.8 nominal, 8 amps Maximum
Common
-20dBm 100 mW
PTT - to ground
TX RX
Common
YES
1
Split
1-10W Other____________
TTL - Positive Voltage
High Low
Separate TX & RX
NO
Rev. H 10/11/2005
Open