[amsat-bb] Sequencer advice needed

[John Kludt]

Roger,

I am a little confused by your comment on frequency range and power as
those are characterists of the relays themselves and not the sequencer.
The purpose of the sequencer is to switch equipment and feedlines from
receive to transmit and back in a orderly sequence such that RF is the last
thing applied on transmit and the first thing removed on receive.  As such
a sequencer is an electrical device and not a RF device.

On my 1296 system I use the Demi solid state sequencer.  Step 1 removes
preamp power.  Step 2 switches the preamp out of line by activating two
coaxial relays (where I spent real money!).  Step 3 grounds the PTT on the
W6PQL power amplifier and then Step 4 grounds the PTT on the transceiver
and applies RF.  There are other switching schemes but this is a fairly
common one.

Hope that helps.

Johnny

On Fri, Mar 6, 2020, 11:50 Roger - W7TZ via AMSAT-BB <amsat-bb at amsat.org>
wrote:

> I've used the W6PQL (built and tested) unit for 6m and 1.25m very
> successfully for several years.
>
> 73, Roger
> W7TZ
> CN83ia
>
>
> On Fri, Mar 6, 2020 at 4:26 AM Hans BX2ABT via AMSAT-BB <
> amsat-bb at amsat.org>
> wrote:
>
> > I haven't worked with sequencers before as all my LNAs and SDRs have
> > been used for receive only. But now that I have a Airspy HF+ I want to
> > get going with APRS on 145.825 and use this on HF as well. So receiving
> > with the SDR, transmitting with a transceiver. I also want to experiment
> > with LNAs, so another reason to use a sequencer. I did a lot of
> > googling, learned some, but still not sure what I need to look out for
> > when buying one. I prefer a kit or assembled product as a first try.
> >
> > Below is a list of what I found on line. From a distance the VHF Design
> > is cheap and has detailed information, so I am leaning towards
> > purchasing that. Later, for a DIY project, I like the OZ1BXM design
> > because it uses an Arduino for control, which brings some flexiblity.
> >
> > Can you all please give me some input on what to look for in sequencers
> > or comment on the choices below? Any other kits/assemblies I have missed
> > and should be considered? Cheers,
> >
> > Hans
> > BX2ABT
> >
> >
> >
> > Minikits from Austalia's EME166: AU$45 (=US$27.75)
> >
> > https://www.minikits.com.au/Sequencer?search=Sequencer
> >
> > This is the only one that indicates a frequency range: 28 to 500 MHz, so
> > this will cover the 2m band, but not HF. Also RF input is 4 Watts
> > maximum, which seems low, so how is this usable?
> >
> >
> >
> > W6PQL's sequencer (US$20 for kit, US$37.50 assembled)
> >
> > http://www.w6pql.com/relay_sequencer.htm
> >
> > No info on frequency range or input power. Not much info on the website.
> >
> >
> >
> > VHF Design (US$20 assembled)
> >
> > https://vhfdesign.com/other/sequencer-pcb.html
> >
> > Website has good information, diagrams and PCB layouts. Again no info on
> > frequency range, etc.
> >
> >
> >
> > Downeast Microwave (US$25~80)
> >
> >
> >
> https://www.downeastmicrowave.com/searchresults.asp?Search=sequencer&Submit=
> >
> > 3 and 4 step sequencers both in solid state and with relays based on a
> > design by W5LUA. Which better: solid state or relays? Little indept info.
> >
> >
> >
> > G3SEK - (DIY)
> >
> > http://www.ifwtech.co.uk/g3sek/dx-book/sequencer/
> >
> > Basically only a schematic, so need to build it from the ground up.
> >
> >
> >
> > OZ1BXM (DIY)
> >
> > http://oz1bxm.dk/seq/sequencer.html
> >
> > Another DIY project based on the W6PLQ design. This uses an Arduino as
> > MCU, so should be flexible. No kits and no PCB designs.
> >
> >
> >
> > SM2CEW (DIY)
> >
> > http://sm2cew.com/sequencer/sequencer.html
> >
> > This one looks very simple to make with very few components. It was
> > designed for HF, so will it work on VHF?
> >
> >
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> _______________________________________________
> Sent via AMSAT-BB at amsat.org. AMSAT-NA makes this open forum available
> to all interested persons worldwide without requiring membership. Opinions
> expressed
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>