The personal website of Scott W Harden
May 27th, 2010

AJ4VD Gator Spotted in MA

That's over 1,00 miles on a few milliwatts! The transmitter is the ridiculously simple one pictured below. I'm blown away! It was seen on running QRSS VD software! Awesome!!

Markdown source code last modified on January 18th, 2021
---
title: AJ4VD Gator Spotted in MA
date: 2010-05-27 11:24:17
tags: qrss, old
---

# AJ4VD Gator Spotted in MA

__That's over 1,00 miles on a few milliwatts!__ The transmitter is the ridiculously simple one pictured below. I'm blown away! It was seen on [ running ](http://w1bw.org/drupal/grabber)[QRSS VD](http://www.SWHarden.com/qrssvd/) software! Awesome!!

<div class="text-center img-border img-medium">

![](map.jpg)

[![](gatorSeen_thumb.jpg)](gatorSeen.jpg)
[![](actual_thumb.jpg)](actual.jpg)
[![](IMG_3456_thumb.jpg)](IMG_3456.jpg)

</div>

May 27th, 2010

AJ4VD Gator Chomps its way into Belgium!

Yeah, that's over 4,500 miles away! The following image was captured from ON5EX's QRSS grabber in Belgium! Amazing. I don't have the equipment to measure its power output, but it's running on USB power and I'd assume it's putting out less than 100mW. Very cool!

Markdown source code last modified on January 18th, 2021
---
title: AJ4VD Gator Chomps its way into Belgium!
date: 2010-05-27 21:38:03
tags: qrss
---

# AJ4VD Gator Chomps its way into Belgium!

__Yeah, that's over 4,500 miles away!__ The following image was captured from [ON5EX's QRSS grabber](http://www.on5ex.be/grabber/grabber.html) in Belgium! Amazing. I don't have the equipment to measure its power output, but it's running on USB power and I'd assume it's putting out less than 100mW. Very cool!

<div class="text-center img-border">

[![](aj4vd_gator_belgium_thumb.jpg)](aj4vd_gator_belgium.jpg)

</div>

May 26th, 2010

Pushing and Pulling

I found a way to quadruple the output power of my QRSS transmitter without changing its input parameters. Thanks to a bunch of people (most of whom are on the Knights QRSS mailing list) I decided to go with a push-pull configuration using 2 pairs of 4 gates (8 total) of a 74HC240. I'll post circuit diagrams when I perfect it, but for now check out these waveforms!

First of all, this is the waveform before and after amplification with the 74HC240. I artificially weakened the input signal (top) with a resistor and fed it to the 74HC240. For the rest of the images, the input is 5v p-p and the output is similar, so amplification won't be observed. The wave I'm starting with is the output of a microcontroller which is non-sinusoidal, but this can be fixed later with lowpass filtering.

Here you can see the test circuit I'm using. It should be self-explanatory.

Here's the output of the microcontroller compared to the in-phase output of the 74HC240

Here are the two outputs of the 74HC240. 4 of the gates are used to create output in-phase with the input, and the other four are used to create out-of-phase wave. Here are the two side by side. The top is 0 to 5v, the bottom is 0 to -5v, so we have a push-pull thing going on... woo hoo!

The waves, when overlapped, look similar (which I guess is a good thing) with a slight (and I mean VERY slight) offset of the out-of-phase signal. I wonder if this is caused by the delay in the time it takes to trigger the 74HC240 to make the out-of-phase signal? The signal I'm working with is 1MHz.

Okay, that's it for now. I'm just documenting my progress. 73

Markdown source code last modified on January 18th, 2021
---
title: Pushing and Pulling
date: 2010-05-26 07:42:39
tags: circuit, amateur radio, old
---

# Pushing and Pulling

__I found a way__ to quadruple the output power of my QRSS transmitter without changing its input parameters. Thanks to a bunch of people (most of whom are on the Knights QRSS mailing list) I decided to go with a push-pull configuration using 2 pairs of 4 gates (8 total) of a 74HC240. I'll post circuit diagrams when I perfect it, but for now check out these waveforms!

<div class="text-center img-border">

[![](qrss_amplified1_thumb.jpg)](qrss_amplified1.jpg)

</div>

First of all, this is the waveform before and after amplification with the 74HC240. I artificially weakened the input signal (top) with a resistor and fed it to the 74HC240. For the rest of the images, the input is 5v p-p and the output is similar, so amplification won't be observed. The wave I'm starting with is the output of a microcontroller which is non-sinusoidal, but this can be fixed later with lowpass filtering.

<div class="text-center img-border">

[![](qrss_74hc2401_thumb.jpg)](qrss_74hc2401.jpg)

</div>

Here you can see the test circuit I'm using. It should be self-explanatory.

<div class="text-center img-border">

[![](qrss_inPhase1_thumb.jpg)](qrss_inPhase1.jpg)

</div>

Here's the output of the microcontroller compared to the in-phase output of the 74HC240

<div class="text-center img-border">

[![](qrss_out_of_phase1_thumb.jpg)](qrss_out_of_phase1.jpg)

</div>

Here are the two outputs of the 74HC240. 4 of the gates are used to create output in-phase with the input, and the other four are used to create out-of-phase wave. Here are the two side by side. The top is 0 to 5v, the bottom is 0 to -5v, so we have a push-pull thing going on... woo hoo!

<div class="text-center img-border">

[![](qrss_out_of_phase_overlap1_thumb.jpg)](qrss_out_of_phase_overlap1.jpg)

</div>

The waves, when overlapped, look similar (which I guess is a good thing) with a slight (and I mean VERY slight) offset of the out-of-phase signal. I wonder if this is caused by the delay in the time it takes to trigger the 74HC240 to make the out-of-phase signal? The signal I'm working with is 1MHz.

__Okay, that's it for now.__ I'm just documenting my progress. 73
May 24th, 2010

Solar Powered QRSS Transmitter

Haray! I'm making awesome progress with my QRSS transmitter design. Because my current transmitter (previous few posts) was randomly freezing-up (likely due to the oscillator stopping its oscillating due to being overloaded) so I moved the oscillator from in-chip to an external oscillator. It's been made small enough to fit in an Altoids tin, and I already tested it with the solar panel and it works! Awesome! Here are some photos. Again, when I perfect the design I'll post final schematics.

Sticking out are wires for power and an antenna on each side. The goal is to hang the device between two trees by its own antenna. That's my new chip development board. I made it with what I needed on it. It's so convenient! It uses 5v of power from the USB port too! Altogether I've tested the device and confirmed it transmits radio when the solar panel is illuminated. I'm thinking of making it more effective by adding more panels... but that's it for now!

Markdown source code last modified on January 18th, 2021
---
title: Solar Powered QRSS Transmitter
date: 2010-05-24 07:47:01
tags: qrss
---

# Solar Powered QRSS Transmitter

__Haray!__ I'm making awesome progress with my QRSS transmitter design. Because my current transmitter (previous few posts) was randomly freezing-up (likely due to the oscillator stopping its oscillating due to being overloaded) so I moved the oscillator from in-chip to an external oscillator. It's been made small enough to fit in an Altoids tin, and I already tested it with the solar panel and it works! Awesome! Here are some photos. Again, when I perfect the design I'll post final schematics.

<div class="text-center img-border">

[![](DSCN0532_thumb.jpg)](DSCN0532.jpg)

</div>

<div class="text-center img-border img-small">

[![](DSCN0533_thumb.jpg)](DSCN0533.jpg)
[![](DSCN0535_thumb.jpg)](DSCN0535.jpg)
[![](DSCN0537_thumb.jpg)](DSCN0537.jpg)
[![](DSCN0539_thumb.jpg)](DSCN0539.jpg)

</div>

__Sticking out__ are wires for power and an antenna on each side. The goal is to hang the device between two trees by its own antenna. __That's my new chip development board.__ I made it with what I needed on it. It's so convenient! It uses 5v of power from the USB port too! __Altogether__ I've tested the device and confirmed it transmits radio when the solar panel is illuminated. I'm thinking of making it more effective by adding more panels... but that's it for now!
May 22nd, 2010

First QRSS Spot!

I'm so excited! This little transmitter I made and programmed to transmit my call sign (AJ4VD) and a picture of a gator got its first spotting tonight! I'm so excited. It was reported by W4HBK in Pensacola, FL. It's only 300 miles away, but it's a start! I'm keeping my fingers crossed and maybe someday soon I'll hear from Europe.

Markdown source code last modified on January 18th, 2021
---
title: First QRSS Spot!
date: 2010-05-22 22:47:03
tags: qrss
---

# First QRSS Spot!

__I'm so excited!__ This little transmitter I made and programmed to transmit my call sign (AJ4VD) and a picture of a gator got its first spotting tonight! I'm so excited. It was reported by [W4HBK](http://www.qsl.net/w4hbk/W4HBKgrabber.html) in Pensacola, FL. It's only 300 miles away, but it's a start! I'm keeping my fingers crossed and maybe someday soon I'll hear from Europe.

<div class="text-center img-border">

[![](spotNice_thumb.jpg)](spotNice.jpg)

[![](simple_qrss_transmitter_thumb.jpg)](simple_qrss_transmitter.jpg)

</div>

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