Ensemble RXTX Builders' Notes

External Connections Introduction

General

Congratulations! You have successfully built and (unit) tested your Ensemble SDR transceiver for the chosen "super-band".

This is the wrap-up stage, where we connect the rig to the outside world (PC (SDR program and soundcard), antenna, and paddles and actually put the transceiver through it paces.

The builder may, at this point, want to consider the hardware and software offerings (PSDR-IQ and USB2SDR card) from Christos SV1EIA (sv1eia@gmail.com). This combination represents the best quality software and hardware interface between the computer and the Ensemble RXTX.

Depending upon the option you have chosen to build and how you wish to operate within that built option, you may need to provide additional low-pass filtering between the transceiver and the antenna. The FCC requires that the mean power of any spurious emission from a station transmitter or external RF amplifier transmitting on a frequency below 30 MHz must be at least 43 dB below the mean power of the fundamental emission. In the case of an 80m (3.5 MHz) transmitter, we must ensure that the mean power at the second harmonic (40m - 7.0 MHz) must be at least 43db below that of the fundamental 80m emission. This rule applies to the RXTX Ensemble. With the current design, the following options require low-pass filtering in order to reduce the second (and higher order) harmonics for the following options to at least 43 dB below that of the fundamental (first-mentioned) band (assuming you want to operate in that band):

Band Option	Use LPF When Operating At	To Attenuate 2nd Harmonic At
80/40m	(80m) 3.5 MHz	7.0 MHz
40/30/20m	(40m) 7.0 MHZ	14 MHz
30/20/17m	(30m)10.1 MHz	20.2 MHz

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External Connections Schematic

(Resistor testpoints (hairpin, top, or left-hand lead), as physically installed on the board, are marked in the schematic with red dots)

(Click for Full Schematic)
External Connectionsschematic

(above schematic has clickable areas that can be used for navigation)

(go directly to build notes)

External Connections Bill of Materials

Stage Bill of Materials

(resistor images and color codes courtesy of WIlfried, DL5SWB's R-Color Code program)

Check	Count	Component	Marking	Category
❏	1	4 X #4-40 hdw (nut, bolt, washer, spacer)		HDW
❏	7	band-specific		misc

Band Specific Items for 80, 40m Band

Check	Designation	Component	Marking	Category	Circuit
❏	C200	390 pF 5%	391	Ceramic	External Connections
❏	C201	1000 pF 5%	102	Ceramic	External Connections
❏	C202	390 pF 5%	391	Ceramic	External Connections
❏	L200	2.5uH: 29T #26(17in) on T37-6 (yel)	yellow	Coil	External Connections
❏	L200-core	T37-6 toroid core	yellow	Toroid	External Connections
❏	L201	2.5uH: 29T #26(17in) on T37-6 (yel)	yellow	Coil	External Connections
❏	L201-core	T37-6 toroid core	yellow	Toroid	External Connections

Band Specific Items for 40, 30, 20m Band

Check	Designation	Component	Marking	Category	Circuit
❏	C200	220 pF 5%	221	Ceramic	External Connections
❏	C201	470 pF 5%	471	Ceramic	External Connections
❏	C202	220 pF 5%	221	Ceramic	External Connections
❏	L200	1.3uH: 18T #26(12in) on T37-2(red)	red	coil	External Connections
❏	L200-core	T37-2 toroid core	red	Toroid	External Connections
❏	L201	1.3uH: 18T #26(12in) on T37-2(red)	red	coil	External Connections
❏	L201-core	T37-2 toroid core	red	Toroid	External Connections

Band Specific Items for 30, 20, 17m Band

Check	Designation	Component	Marking	Category	Circuit
❏	C200	100 pF 5%	101	Ceramic	External Connections
❏	C201	330 pF 5%	331	Ceramic	External Connections
❏	C202	100 pF 5%	101	Ceramic	External Connections
❏	L200	0.9uH: 15T #26(10 in) on T37-2 (red)	red	Coil	External Connections
❏	L200-core	T37-2 toroid core	red	Toroid	External Connections
❏	L201	0.9uH: 15T #26(10 in) on T37-2 (red)	red	Coil	External Connections
❏	L201-core	T37-2 toroid core	red	Toroid	External Connections

External Connections Summary Build Notes

Connect I and Q leads
Connect USB
Connect Antenna
Connect Keyer
Connect Power
Install In Enclosure (Optional)
Load and Run SDR Software
Build and Connect External LPF
Test the Stage

External Connections Detailed Build Notes

Top of the Board

Connect I and Q leads

Recently, there have been extensive discussions on the reflector concerning the fact that some builders have a combination of soundcard, software, PC, and operating system in which the jumpers/leads for the TX I and Q signals must be the reverse of the jumpers/leads for the RX I and Q. This has been pretty much a case-by-case experience. We are building a spreadsheet depicting various combinations of the relevant variables (soundcard, program, kit, PS, OS, etc.) and the wiring that "works" for the RX and TX I and Q signals.

The IQ connections are via stereo cables, male-to-male, 1/8" plugs, connecting:

"Line In" on the board to the "Line-In" (STEREO) input jack on the PC or sound card
"Line Out" on the board to the "Line-Out" (STEREO) output jack on the PC or sound card

Connect USB

Connect Antenna

Connect Keyer

Connect Power

Install In Enclosure (Optional)

One possibility for a nice enclosure for this rig is the Specialty Bottle Rectangular, Windowed Tin.

Another - and a very nice one at that - is the enclosure offered by Tom KM5H on his website

Load and Run SDR Software

Build and Connect External LPF

Note: if you intend to operate on 80m, 40m, or 30m, you MUST build special low-pass filters for those bands and connect it/them between your kit's antenna jack and the antenna. The LPFs are designed for the lowest freq band in the group ( 80 for the 80/40, 40 for the 40/30/20, and 30 for the 30/20/17 ). Thus, the external LPFs are built for and used in the antenna feed as follows: