Products from KD9SV Gary Nichols

E-Mail Gary for Technical information at
kd9sv@comcast.net
 

For Pricing and Ordering  information contact 

DX Engineering


 

 

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.......