Remote Coax Switch (RCS)

Bare Printed Circuit Boards (PCBs #14 and #15)

(PC Boards Only)

Described below is a Remote Coax Switch system consisting of two (PCBs #14 and #15) that interoperate to create the system. In order to provide the most flexibility to users, the PCBs are being offered as a pair, as well as individually, for those wishing to use one for a future project.

Price: $ 30.00 including shipping to a US address. 

Photo 1 – Representative Construction of AWA Remote Coax Switch

Description:

This pair of PCBs allows you to build a low cost remote controlled coax switch.  The RCS Antenna End PCB #14 is comprised of a relay switch matrix that uses a 2-wire control interface to select 1 of 4 antenna ports (see block diagram in Figure 1).  The RCS Transmitter End PCB#15 converts 110VAC or 220VAC to voltage levels compatible with the relay control on the Antenna End board utilizing a rotary switch.  A small LED PCB provided with the Transmitter End PCB is used along with the rotary switch as an indicator of which antenna has been selected.

Schematics and representative parts lists will be shipped with each board.

Figure 1.  Block Diagram of AWA Remote Coax Switch

RCS Antenna End PCB#14

Price $17

We believe this product to be competitive with others found on the market.  It is important to understand the many competitors will lead you to believe that the general purpose relays that are used in these designs are capable of over 1500W given their AC contact ratings.  However, we want you to know that this is poor practice as relay contacts of this nature need to be de-rated for various factors including operating frequency, altitude and SWR.  We have conservatively specified our switch based on a proposed set of operating conditions.  That said, we believe that you could exceed the specified power output by operating well within these specified conditions.  It is the users responsibility to determine the operating limits of this switch beyond our specification.

Photo 2.  Top Side view of Assembled and Bare PCB#14.

PCB#14 Utilizes an arrangement of 3 SPDT relays that are controlled by a 2 wire interface.  This interface is controlled by the PCB#15 located at the Transmitter location. The voltage selection of +12VDC, -12VDC, 12VAC or 0V is made by PCB#15 Assembly.

PCB #14 has the following specifications:

RF Range: 1.8-30MHz

Insertion Loss: 0.05dB typical @30MHz

Port Isolation: -34 dB typical @30MHz

Command RF isolation: -61dB @30MHz

Recommended RF Power Limits: Conditions – CW or FM continuous @30MHz, Max SWR 2:1

               1000W @ Sea Level

               700W @ up to 5000ft Above Sea Level.    

Command Current : 117 mA Max (Ant2 selected-all relays ON)@20C

Dimensions:

PCB#14 is 1 1/2″ (H) X 3 1/2″ (W) X 3 15/16″ (L).

Photo 3. RCS PCB #14 Assembly Bottom View

Below are a series of downloadable PDF documents and a tool to assist with your efforts to construct this transmitter:

Considerations:

This offering is for the bare PCB(s) only and additional components are required. See Additional board component costs below.   

Lighting protection is essential for antenna systems.  It is the responsibility of the end user to design a proper lightning protection system.  Information is available through the American Radio Relay League to assist with this design.

Switching Antennas while transmitting is not recommended.  There is no automatic protections built in for this situation.  Also, there is no automatic SWR sensing in this system.  The user must make sure that he is operating with the proper antenna for the frequency of transmission.

Spurious Emissions can cause erratic behavior of this system.  This can happen when either SWR is drastically too high (>2:1) or an imbalance exists in the antenna(s).  The user is responsible for insuring that their antennas are optimized and working properly in this regard.

Additional PCB #14 Component costs under $25:*

*Note that above parts pricing is approximate and does not include shipping, tax or tariff costs.

*Note also that housing for the assembly is not included in additional parts costs.

PCB#14 Build Notes:

Preparation and planning for the final assembly will make the build effort more manageable.  It will be important to identify an enclosure in advance of final board assembly. 

• A plastic enclosure (recommended) is likely the simplest application in that a bulkhead mounting of the completed PCB assembly will not require spacing.  However, it will require additional length screws to accommodate additional thickness of plastic bulk head.  You may opt to eliminate the 4 PCB mounting holes in this case as there will be plenty of stability provided by the connector mounting screws.

• A metal mounting surface will require stand-offs (min 1/4”) for the PCB. Mounting of the coax connectors  to the metal bulkhead will be necessary.  The stand-offs should be metal, as the RF return path for the coax will be made to the ground plane of the PCB through the PCB mounting pads.

• In either housing selection, hole locations may be facilitated using the downloadable drill template.  Be sure to download template instructions along with the templates in order to insure location accuracy of your prints.

Table 1. will help in debug if needed.

Table 1.  RCS Antenna End PCA State Table.

Additional Notes:

1. J2-J6 are mounted from the bottom (non-component) side of the board.  See Photo 3.
2. Center contact for J2-J6 to board connection should be made with 14AWG stranded wire with length as short as possible.
3. Observe polarity of Command signal connection.

RCS Transmitter End PCB #15

Price $13

Photo 4.  Top Side view of Assembled and Bare PCB#15.

PCB#15 is the control board for the AWA Remote Coax Switch.  It is comprised of a linear DC power supply that produces +/-12VDC.  12VAC is taken from the transformer output before the rectifier section.  These three voltage levels along with 0V is selected using a rotary switch.  A companion board holds 4 LEDs that serves to indicate which antenna is selected.

Specifications:

Power Inputs:  110VAC/60Hz/100mA rated

                         220VAC/50Hz/50mA rated

Output Current: 200mA Max.

Dimensions: 1 5/8″ (H) X 2 7/8″ (W) X 3 1/8″ (L)

Downloadable Information:

Considerations:

This offering is for the bare PCB(s) only and additional components are required. See Additional board component costs below.   

Additional PCB# 15 Component costs under $29:*

*Note that above parts pricing is approximate and does not include shipping, tax or tariff costs.

*Note also that housing for the assembly is not included in additional parts costs.

This offering is for the bare PCB only and additional components are required. 

PCB Info Help

If you have any questions, contact the staff at: AWAHelpDesk@antiquewireless.org.

Ordering Options:

On-Line Store

Additional Information

To request an AWA Membership discount or shipping information for Non-US shipping, utilize the form below. Be sure to specify the PCB Item # and the quantity of each board in your request.