E-Mail
Gary for Technical information at
kd9sv@comcast.net
For Pricing and Ordering information contact
Front
End Protection for your Transcievers
This device removes the receive antenna from your radio during transmit
cycle as well as Inhibiting the Amplifier if the box fails to
operate....thereby
saving the front end of your radio....
All the radios produced by Icom, Kenwood, Yaesu & TenTec
Elecraft
have the same problem...
they do NOT turn off the receiver during transmit ....
I figured this out after the 2nd time I blew the front end in my Icom
IC-765.
The Front End Saver also gives you a nice hefty relay to
key your amplifier rather than killing the very small low current relay
in
the transmitter......
DXPED
II
Dxpedition II Model Antenna Switch with Dual 80/160
Pre-amp For use with Transceivers “with or without” an RX
input
This device was designed with the “Low-Band” operator in
mind. The
purpose is to provide capability to use separate receive antennas
with
radios that do not have a RX antenna input.
This device provides antenna switching to allow using separate transmit
and receive antennas.
During Receive the
Dxpedition II Model does:
Selection of up to 4 different receive only antennas
Select to receive on either Transmit Antenna or Receive only antennas
by switching to either Xmit or Bev. Xmit position selects the
transmit
antenna for both receive and transmit.
Bev position selects aux rec antennas. Provides 20+ db adjustable gain
on 80 and 160 meter band.
During Transmit the Dxped Model provides for:
Disconnecting of your Receive antenna and switches to the
transmit
antenna. A “Soft keying” circuit (3.5vdc @ 1.5ma) protects your
transceivers fragile T/R relay while providing a
solid-state keying relay for your linear amplifier. This
solid-state
relay is rated at 500v 8 amps and will key any positive voltage
amplifier without danger of damage to your rigs fragile
keying circuits. This circuit works with either QSK or non-QSK
type
amplifiers. Semi-break-in is the preferred method of keying however the
changeover circuits are fast enough for full-break-in.
Note: this keying relay will not work with amplifiers that have
negative voltage keying circuits like the SB200,Yaesu FL-2100B or
Collins 30L-1
DXPED
Pre-Amp
Dxpedition Model Antenna Switch with Dual 80/160
Pre-amp
This device was designed with the “Low-Band” operator in
mind. The purpose is to provide protection for your transceiver
by preventing your transmitted
RF from causing damage to your rig’s input circuitry (Front-end) while
also providing Receive Antenna selection and amplification for
low-output low-noise
receive antennas such as Flags, Pennants, loops and beverage antennas
on 80 and 160 meter bands.
During Receive the Dxped
Model does the following:
Selection of up to 4 different receive only antennas
Select to receive on either Transmit Antenna or Receive only antennas
Provides 20+ db adjustable gain on 80 and 160 meter band.
During Transmit the Dxped Model provides for:
Disconnecting of your Receive antenna and shorting
the input antenna port to ground to protect from RF overload and
Front-End damage.
Provides a Solid-state keying Relay rated for 500v at 8 amps for Keying
positive voltage of your Linear Amplifier thereby protecting the
“Fragile” T/R keying
relay of your transceiver. This “Soft Keying Circuit” requires only
grounding of 3.5vdc @ 1.5ma by your rigs T/R relay or QSK output. This
keying relay is
adequate for either QSK compatible amps or the older non-QSK amplifiers
ie TL922A, SB220 etc. Semi-break-in is the preferred operating
mode however
the relays are fast enough for full break-in or QSK operation.
Note: the solid state keying relay will not key negative voltage
amplifiers
Like the SB200, Yaesu FL-2100B or Collins 30L-1
SV-160
KD9SV 160 meter Pre-amp
The KD9SV 160 meter Pre-amp has
been re-designed for better noise figure and increased gain using
the BF981 FET which has a typical noise figure of 0.7db. This
amplifier is designed for use with low-noise antennas such as Loops,
Pennants, Flags or Beverage type of antennas that had a low
output and required amplification. Switching from IN to OUT
places the preamp in the “bypass” mode when not needed or when using
other bands.
The KD9SV Pre-amp
has both a tuned input and tuned output which gives the amp a large
amount of Broadcast Station rejection, typically about 45db at
1mhz. Gain is front panel adjustable from 10db to approx 28db
which is more than enough gain to bring low-noise antennas to
life. Having this additional gain added to a low noise antenna
can make the difference between hearing and not hearing weak DX
stations on 160 meters.
Although the back
panel is marked 12vdc, the amplifier will typically run on the DC
voltage available from the back panel of nearly all transceivers, which
in reality is 13.5 to 13.8vdc.
It is recommended
that “Front-end-protection” be used with any antenna connected to the
“Aux Ant Input” of typical transceivers, as that Antenna Port is
“Active” during transmit and excessive amounts of RF coming back into
your transceiver during transmit can cause damage to the
transceiver. Any front-end-protection device that will disconnect
the receive only antenna during transmit should also ground the RX
input at the same time. KD9SV also can provide this product
complete with a “Soft Keying” capability to protect the fragile keying
relay of the newer transceivers. Such a device was
described in CQ Magazine, Feb 97
SV-ATMI
9:1 Beverage Antenna Matching Transformer
This Transformer will match the 450 ohm Beverage Antenna
impedance to the 50 ohm impedance of your Coax resulting in the proper
transfer of signals to your receiver.
Note: This is a “Receive only device and not intended to be
Transmitted into. Transmitting into this device will eventually
cause it to fail.
SV-BPF
160 Meter BandPass Receive Filter
This Filter is intended for use where local Broadcast Stations cause an
overload condition to transceiver operation when using Receive antennas
such as “Beverage Type” or long wire antennas.
The Filter will pass 1.8 to 2.0 mhz signals with approximately 0.5db
insertion loss when terminated with 50 ohm source and load
impedance. BC rejection is as follows:
0.5mhz approx –60db
1.0mhz >45db
1.5mhz >20db
SV-CMC
Common mode Choke
This Device is designed to offer a hign impedance path to remove any
unwanted signals from entering your radio from the shield of the coax
cable coming from your receive antenna. This Choke offers a
minimum of 3000 ohms resistance between the input and output shield
terminals. That is enough resistance to prevent the common mode
signals being picked up by your antenna coax from adding to the noise
floor of your receive system. In some cases the noise floor of
your receiver can be reduced by as much as 2 S-units
To use simply connect this device to the RX input of your radio with a
short coax cable and the antenna will connect to the Input of the
Common Mode Choke.
SV-DB
KD9SV 80/160 meter Pre-amp
The KD9SV 80/160 Pre-amp has been re-designed for better
noise figure and increased gain using the BF981 FET which has a typical
noise figure of 0.7db. This Preamp is designed for use with
low-noise antennas such as Loops, Pennants, Flags or Beverage
type of antennas that had a low output and required
amplification.
The KD9SV 80/160 Pre-amp has both a tuned
input and tuned output which gives the amp a large amount of Broadcast
Station rejection, typically about 45db at 1mhz. Gain is front
panel adjustable from 10db to approx 28db which is more than enough
gain to bring low-noise antennas to life. Having this additional
gain added to a low noise antenna can make the difference between
hearing and not hearing weak DX stations on 160 and 80 meters.
Switching the pre-amp “Off” by turning the gain
control fully CCW places the pre-amp in “By-Pass” mode for reception on
other bands with your RX antennas.
It is recommended that “Front-end-protection” be
used with any antenna connected to the “Aux Ant Input” of typical
transceivers, as that Antenna Port is “Active” during transmit and
excessive amounts of RF coming back into your transceiver during
transmit can cause damage to the transceiver. Any
front-end-protection device that will disconnect the receive only
antenna during transmit should also ground the RX input at the same
time. KD9SV also can provide this product complete with a “Soft
Keying” capability to protect the fragile keying relay of
the newer transceivers. Such a device was described in CQ
Magazine, Feb 97
Magic
Tee
These
products
can
be purchased from DX-Engineering.
This
page is Sponsored by John k9uwa Avid 160 meter operator...when we are
not
working new ones
on
Top Band we spend our time restoring old radios......"Wood
Boxes"....well
once in a while a metal box
To
see our Home page "JohnJeanAntiqueRadio.com"
click here.......