Hard Rock:A Modular Approach to

Experimental Radio

Rick CampbellKK7B

Portland State University

Electronic Component Vending Machine run by IEEE Student Store

http://web.cecs.pdx.edu/~campbell/

Hardware Defined RadioClassic Rock

Garage Bands and Covers

Soft Rock

Easy Listening

Cover -- Take someone else’smaterial and reproduce it

GDR

Original Material

Experiment

Learn the Rules

...and then Break Them

Or you can do....

Rick Hulett

The Hard Rock Approach

Focus on each module independently

Test each module independently

Analog Inputs and Outputs

Swap modules to modify the sound

Hard Rock Experimental Radio

Hard Rock Block Diagram

The Modules:

The Antenna is the first stage of the receiver. Design the rest accordingly

Receive Antenna Coupler

Put the Volume Control where it does some good

Dynamic Range

Receive Antenna Coupler

Front-End Crystal Filter

Low DC Power 40m ReceiverRick Campbell 15 Mar 2009

H1 7 MHz 50 ohm quadrature hybrid: 18 turns bifilar on T37-2 (1.1 uH) and two 220 pF capacitors. L1 and L2 12 turns FT37-43. T1 8 turns trifilar on FT37-43. JFET Hartley VFO component values determined experimentally: see many examples in EMRFD. Gain from antenna input to 50 ohm head-phone output is 50 dB: use good antenna and sensitive headphones

This receiver was designed and built as an exercise in sustainable radio engineering: minimum DC power requirements with fundamental concepts, components and techniques that have been around for 50 years and will still be useful for another 50. Performance falls in the wide gap between minimalist designs and good basic receivers such as the microR2. The major performance compromises to achieve ultra-low DC power with common components are opposite sideband suppression, gain, and 2nd and 3rd order dynamic range. Gain and dynamic range limitations may be addressed by using a full-sized elevated dipole antenna fed with ladder line and a high Q impedance matching network such as a Johnson Matchbox. Suppression of an interfering signal or carrier on the opposite sideband may be achieved by adjusting the input Pi network and IQ balance pot to null the offending signal. Experiments are in progress to reduce the power consumption of the Local Oscillator.

L3

730pF

51

2uH

C1 2.7

J310

1N4148100n

1002.2k

33mH

12k

3.9k

680p

2N3904

2N3904

3

1

2

7

5

6

1.8k27k

27k

3.3k430p

768k

487k

+

+

33u

33u

1u680n

3.9mH

100u+

22k

10k

22n

2N3906

2N3906

12k

3.9k

680p

2N3904

2N3904

1.8k27k

27k

3.3k430p

196k

124k

+

+

33u

33u

1u680n

3.9mH

22k

10k

22n

2N3906

2N3906

2Q4

+100u

1k8

10 390

270

4.5v

4v

220k

220k

33u

+ 1.5uF

T1

10nF

51

730pF10nF

T2

H1

L1

L2

1N4148

1M

C2

9v 4 mA

IQ Diode Detector

Local Oscillator

B&W

4v 2.5 mA

10k

With a good antenna and receive coupler, the rest of the system may be Primitive and Simple

But sometimes we want something better

Image-Reject Downconverter

iR2 Instrumentation Receiver

RF Signal Path Block Diagram

RF LO

0

0

0

90

I

Q

Top half of the circuit board. Note all the gain and RF selectivity. This is a different approach to receiver design that works well on a selected

narrow band between 50 kHz to 250 MHz

This is not the way to build a receiver that covers every amateur band from 160 to 6m!

2 dB Noise FigureSerious selectivity before the IQ mixers

Analog Signal Processor

Analog Signal Processing Block Diagram

I All-Pass

Q All-Pass

baseband out

Conventional. A few changes related to increased gain ahead of mixers.

Can be built for wide baseband

ADE-1 Diode Ring Mixer

No Mystery Parts! Study the schematicsand see how everything works.

Photo inside the Diode Ring Mixer.Two transformers, 4 diodes.

Some surface mount on back side of board where they improve performance

Complete 50.125 SSB-CW Receiver

Complete 50.125 SSB-CW Receiver

Easy to reconfigure modulesto try different combinations

Sometimes fixed station, sometimes portable, sometimes battery operated on boat

Hard Rock need Valves!

Note: 200 hour battery life of Zenith Transoceanic in 1949

Experiments

One Hardware Module at a Time

Working Experimental System

(One Hardware Module at a Time)

Measure them at the bench

One Hardware Module at a Time

Then Assemble Modules

40m AM Stereo Receiver

You can go deep into system and break it up into modules.

For PA experiments, you can even treat the PA transistor as a module

Experimental goal is to isolate the variables so you can focus on one at a time

Experimental 6 watt 50 MHz Linear PA

Telemetry

Other Applications

Balloons and Rockets

Remotely Operated Vehicles

(Amateur Radio is more than just a bunch of retired Rocket Scientists

touching base every morning)

Students with Sonobouy

Marine Surface Sound Microphone

Modular approach encouragesexperiments

Conclusion:

Hard Rock approach encourages whimsy and fun

Whatever you do...pass it along to the next generation

Thank You