EME168 Bias Tee Kits
- EME168 Kit Description:
Updated! June 2022 - Kit Constructors Alert:
- EME168-HF Kit:
Discontinued - EME168-VHF Kit:
Discontinued
- EME168-6M-2M-1.25M-Band Kit:
- EME168-2M-70CM-Band Kit:
- EME168-70CM-23CM-Band Kit:
- Kit changes and Updates:
Updated! Sep 2021 - Buy a Bias Tee Kit:
There are a number of different EME168 Bias Tee ( DC Power Injector ) products available to cover the HF to UHF bands. All are constructed on the EME168 board that uses a strip line and flange mounted RF connectors for lowest loss. A Hi-Q low loss 1kv capacitor is used along with a low loss choke allowing RF power levels of at least 500 Watt PEP on the VHF to UHF bands.
The EME168-HF Bias Tee was designed to suit the EME162 HF Active Antenna, and is for receive only applications. This Kit has been designed to be used with a HF communications receiver, or on the auxiliary RX antenna connection that is available on many late model HF transceivers. RF power cannot be transmitted through the EME168 HF bias tee. HF Application Block Diagram
The EME168-VHF version was designed to suit 6M, 2M and 1.2M band
masthead preamplifiers and and will handle at least 100 watts.
The EME168-6-2 version is suitable for use between 40 and 200MHz, and has been designed to suit the EME220 series 6, 2 and and 1.25M band preamplifier Kits. The design uses a high Q RF decoupling coil and a high quality low ESR 1kV DC decoupling capacitor, so it will easily handle 500 Watts PEP. This product is particularly suitable as an interface to allow transceivers to be able to switch power through a coaxial cable to a remote preamplifier. VHF Application Block Diagram
The EME168-2-70 version is suitable for use between 100 and 500MHz, and has been designed to suit the new EME220 / 221 series 2M and 70cm preamplifier Kits. The design uses a high Q RF decoupling coil and a high quality low ESR 1kV DC decoupling capacitor, so it will easily handle 500 Watts PEP. This product is particularly suitable as an interface to allow transceivers to be able to switch power through a coaxial cable to a remote preamplifier. VHF Application Block Diagram
The EME168-70-23 version is suitable for use between 400 and 1500MHz, and has been designed to suit the new EME221 series 70 and 23CM band preamplifier Kits. The design uses a high Q RF decoupling coil and a high quality low ESR 1kV DC decoupling capacitor, so it will easily handle 500 Watts PEP. This product is particularly suitable as an interface to allow transceivers to be able to switch power through a coaxial cable to a remote preamplifier. VHF Application Block Diagram
The EME168-HF is a receive only HF Bias Tee that was designed to power the Mini-Kits EME182 HF Active Antenna via the coaxial cable. The Bias Tee can be used either with a HF communications receiver, or with a modern HF transceiver that has a separate RX Antenna socket on the rear. The circuit incorporates a RX to TX changeover circuit so that power can be cut to a HF active Antenna when in transmit mode, to protect the active circuit. The Bias Tee was not designed for transmitting any RF power through it, so should not be used for this purpose. The Bias Tee has a low loss and provides a frequency range of 100kHz to over 300MHz.
Rear view of the EME168-HF Bias Tee Kit. The board is designed to fit a Hammond 1590A die cast enclosure. Click the picture for a larger view.
The above plot shows the S11 return loss of the EME168-HF from 0 to 60MHz.
The above plot shows the S21 through loss of the EME168-HF from 500kHz to 300MHz.
How the RFC choke is fitted to the board, changed to the FT50-43 in Rev2 Kits.
The EME168-VHF was designed to suit both the 6 and 2M bands. The Bias Tee was specifically designed to be used with VHF transceivers that do not have the ability to switch DC power out of the antenna socket to power masthead preamplifiers. The design uses a wound toroid as a choke which provides very low loss, and covers the complete 50 to 300MHz VHF band. The Bias Tee has been designed to handle at least 100 Watts. This Product has been discontinued and replaced with the EME168-6-2, ( 6m and 2m bands ) and EME168-2-70 ( 2m and 70cm bands ).
Rear view of the EME168-VHF Bias Tee Kit. The board is designed to fit a Hammond 1590A die cast enclosure. Click the picture for a larger view.
The above plot shows the S11 return loss of the EME168-VHF from 0 to 300MHz.
The above plot shows the S21 through loss of the EME168-VHF from 0 to 300MHz.
How the RFC choke is fitted to the board.
Front View of the EME168-6-2 Bias Tee with N type connectors.
Rear view of the EME168-6-2 Bias Tee Kit. The board is designed to fit a Hammond 1590A die cast enclosure. Click the picture for a larger view.
Fitting of the inductor RFC1.
How the RFC choke is fitted to the board.
Fitting of the DC jack and RXEF030 Polyswitch.
The above plot shows the S21 through loss of the EME168-6-2 from 20 to 200MHz.
The above plot shows the S11 return loss of the EME168-6-2 from 20 to 200MHz.
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Front View of the EME168-2-70 Bias Tee with N type connectors.
Rear view of the EME168-2-70 Version1 Bias Tee. The board is designed to fit a Hammond 1590A die cast enclosure. Click the picture for a larger view.
Fitting of the inductor RFC1.
How the RFC choke is fitted to the board.
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Fitting of the DC jack and RXEF030 Polyswitch.
The above plot shows the S21 through loss of the EME168-2-70 from 50 to 550MHz.
The above plot shows the S11 return loss of the EME168-2-70 from 50 to 550MHz.
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Front View of the EME168-70-23 Bias Tee with N type connectors.
Rear view of the EME168-70-23 Version1 Bias Tee. The board is designed to fit a Hammond 1590A die cast enclosure. Click the picture for a larger view.
Fitting of the inductor RFC1.
How the RFC choke is fitted to the board.
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Fitting of the DC jack and RXEF030 Polyswitch.
The above plot shows the S21 through loss of the EME168-70-23 from 50 to 2000MHz.
The above plot shows the S11 return loss of the EME168-70-23 from 50 to 2000MHz.
1/ Kits with the new PC board after December 2020 were supplied with a FDN338P MosFET. The MosFET seems a bit marginal with respect to the Vgs only being +/-8v. It is suggested that if it fails then it can be replaced with a higher Vgs MosFET like the DMP3099L-13. Kits supplied after April 20 2021 are now supplied with the DMP3099L-13 MosFET.
2/ All Kits have had minor changes after December 2020. The NDS2955 MosFET switch has been changed to a FDN338P, and a LED has been added to the PCB front panel to indicate power to the Bias Tee.
3/ The EME168-VHF has been discontinued and replaced with the EME168-6-2 ( 6 and 2m bands ), and EME168-2-70, ( 2 and 70cm bands ).
4/ All Kits after September 2016 have had the 10uF capacitor removed on the drain of the NDT2955 MosFET as it is not required, and the 1206LO16 Polyswitch removed and replaced with a wire link. The current handling was also changed by the RXEF010 Polyswitch being replaced with a RXEF030 ( 300mA hold ) type.
5/ Kits after October the 25th 2016 have had the BC847 transistor that drives the NDT2955 MosFET replaced with a 2N7002 MosFET. This improves the switching when the PTT1 connection is used with some Transceivers including the Kenwood TS2000.
6/ Kits after October 2017 have had some PC board improvements Rev1.1 board.
7/ EME168-HF Kits after August 2018 have had some minor changes mainly the BN43-1502 has been replaced with a FT50-43 core with 14 turns of 0.5mm ECW ( 100uH ), for better performance.