Summary of RX/TX SEQUENCER
This RX/TX sequencer is a digital device designed for ham radio to safely manage power transitions between transmitters and sensitive receivers. It utilizes a 12V power supply with reverse-polarity protection and is controlled via a PPT input pulled high by a 10k resistor. This Revision D design ensures reliable switching when using external amplifiers or pre-amplifiers.
Parts used in the RX/TX Sequencer:
- Digital circuitry
- 12V power supply
- PPT input control
- 10k resistor
Much like the beacon keyer presented here earlier, this RX/TX sequencer is a simple but useful little device. Its typical use is in ham radio applications when a separate power amplifier (PA) and/or a sensitive low-noise pre-amplifier (LNA) is used. Care has then to be take to safely transition between RX and TX states – and that’s where this sequencer comes in.
Why a sequencer?
There are many sequencer designs on the web, both analog (http://www.ifwtech.co.uk/g3sek/dx-book/sequencer/) and digital (http://www.mancuso.net.au/sequencer.html) There’s also a beautifully made but somewhat more involved design here: http://www.w6pql.com/relay_sequencer.htm. The links above (and many more) explain the purpose of (and need for) such a sequencer in quite some detail so I won’t repeat it all here.
soldernerd.com on YouTube
Maybe the best way to understand what this sequencer does is to see it in action. I’ve just yesterday started a YouTube channel to share that kind of videos. Here’s the link: https://www.youtube.com/watch?v=Ctxm0VxeM4g.
This is already Rev D
I have designed and built a number of sequencers over the years so this is already revision D. Unfortunately, I don’t seem to have photos of the first two versions.
Input and Output
The sequencer presented here is of the digital variety, uses a 12V power supply and is fully reverse-polarity protected. It is controlled via a PPT input which is pulled high (to +5V) with a 10k resistor and active when pulled to ground.
for more detail: RX/TX SEQUENCER
- What is the typical use of this sequencer?
It is used in ham radio applications to safely transition between RX and TX states when using separate power amplifiers or low-noise pre-amplifiers. - Is this sequencer analog or digital?
The presented sequencer is of the digital variety. - What voltage does the sequencer use?
It uses a 12V power supply. - Does the device have reverse-polarity protection?
Yes, it is fully reverse-polarity protected. - How is the sequencer controlled?
It is controlled via a PPT input which is pulled high to +5V with a 10k resistor and becomes active when pulled to ground. - What revision of the design is described?
This is Revision D of the design. - Can I see the device in action?
Yes, a video demonstration is available on the soldernerd.com YouTube channel.
