Order Cart | Contact Us | Home | SIGs | Login

HPSDR Alexiares RF Bandpass Filters

HPSDR - Alex RF Bandpass Filters

ALEXIARES (or ALEX for short) is a combination RF Preselector for use with Mercury or any other SDR, as well as a transmitter low pass filter bank for a transmitter such as Penelope, and optionally, with an associated RF power amplifier up to 100 watts peak.

ALEX consists of two Euroboard sized PC boards (10 cm by 16 cm). They are intended to be mounted in a commercial Euroboard extruded aluminum housing. The target commercial housing is a Hammond 1455N1601 extruded aluminum case (or equivalent.) ALEX does not plug into the ATLAS bus, but is intended for mounting in Pandora or separately, and is controlled by an SPI bus. There are nine BNC connectors that will extend through to the outside of the filter housing, for external access.

The receive PC board is a HPF board. There is a 6 meter low noise preamp; selectable 20 MHz, 13 MHz, 9.5 MHz, 6.5 MHz and 1.6 MHz high pass filters, plus a bypass function. These are followed by a 55 MHz 7th order Low Pass Filter that is always in line with the receiver.

The receiver board also contains a switchable front end attenuator, configurable for 0 dB, 10 dB, 20 dB or 30 dB loss. It has five external BNC connectors.

The control cable is included with the reciever board.

The transmit PC board is the LPF board. It consists of seven relay switched low pass filters for transmitter harmonic suppression, that are also used in conjunction with the receiver high pass filters to provide a flexible variable bandwidth receiver input filter function. It has four external BNC connectors.

The board RF interconnect cable is included with the transmitter filter board.

The VSWR cable is included with the transmitter filter board.

Each board contains three LEDs, so that an indication of power and proper control and SPI bus operation can be seen. ALEX is controlled by an SPI bus. This SPI bus should NOT be shared with other devices, in that it is intended that the data and clock lines should not be transitioning except when a command is being sent to one of the ALEX boards. There are two analog voltage outputs providing an indication of transmit forward and reverse power. There are no oscillators or continuously running clocks anywhere inside of ALEX.

Availability and Schedule

In stock and shipping.

Alex Warranty


All Alex boards will be tested for basic funtions prior to shipment. This will not garantee any particular performance. To the extent that we have available inventory, we may, at our discretion, agree to a one time only exchange.

This is a low volume production, experimental item. TAPR is a small, not- for-profit organization of volunteers who have helped facilitate this project because we believe it is a cool thing to have. In order for TAPR to be able to offer this board at all, we must rely on the support of all users in the HPSDR community. The Alex boards are basically a group buy that we have chosen to pre-build because of the difficulty of assembly. TAPR expects that Alex buyers will seek help on the OpenHPSDR Discussion List before looking to TAPR for problem resolution.

You are participating in a group purchase. In the event of circumstances beyond TAPR's control, TAPR's only obligation is to provide each purchaser his/her share of the surviving material.

Alex Recieve Filter Bank

This is a completely assembled and tested HPF board plus ribbon cable for the SPI buss connection.

Ordering Information

Sorry, AlexRX A&T is no longer available

Alex Transmit Filter Bank

This is a completely assembled and tested LPF board plus the coax cable for the internal connection to the receiver HPF and the VSWR cable.

Ordering Information

The price for the AlexTX A&T is:

  • $ 176 US for members of TAPR

  • $ 279 US for non-members

    + shipping/handling if applicable.
(Place Web Order)

A note regarding email addresses: When checking out please use an email address other than @earthlink.net, @hotmail.com, @live.com, @msn.com, @outlook.com. For some reason these domains reject email from tapr.org

Shipping and Handling

Shipping and Handling within the US will be by USPS Priority Mail.

International shipping costs are calculated as closely as possible. If the actual cost exceeds the estimate by more than $10.00, TAPR will contact you to get approval for the additional funds. TAPR uses insured Priority Mail International, unless the purchaser requires something else.

Alex Enclosure Kit

This is an extruded housing with custom end plates and hardware for a standalone Alex enclosure or for mounting within Pandora.

Ordering Information

Sorry, AlexEncl is no longer available


Ordering Information

Sorry, Alex RX PCB is no longer available


Notice to buyers of blank Alex-TX PCBs: The Omron G6H-2-DC12 relay used on the Alex-TX board has been discontinued. The Omron suggested replacement is G6S-2-DC12, but it is NOT a direct replacement. Board modifications are necessary in order to use the G6S relay on the Alex-TX board. Be sure that you either have/can get G6H relays or are prepared to find a suitable substitute before you purchase a blank Alex-TX PCB.

Ordering Information

Sorry, Alex TX PCB is no longer available



Other HPSDR kits

Atlas Backplane ... Read more.
Excalibur Reference Oscillator ... Read more.
Janus Audio Converter ... Read more.
LPU Power Supply ... Read more.
Magister USB Interface ... Read more.
Mercury RX Module ... Read more.
Metis Ethernet Interface ... Read more.
Pandora Enclosure ... Read more.
PennyLane TX Module ... Read more.
PennyWhistle PA ... Read more.
Pinocchio Extender Board ... Read more.

About Us | Privacy Policy | Contact Us | ©2005-2020 Tucson Amateur Packet Radio Corp unless otherwise noted.

Accept Credit Cards