VHF Design Sequencer

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Golay

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One of the Yahoo Groups I follow is about Yaesu 847's. There's a post about this piece of equipment hooked to a 847. I've read the post and this link a couple of times, and the fog still isn't lifting. What does this thing do:

https://vhfdesign.com/tag/sequencer

Thanks
 

mancow

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It switches pre-amplifiers and other equipment out of the way of the signal prior to the transmitter's energy reaching them so they don't end up roasted.
 

AK9R

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Weak signal VHF-UHF operators often use mast-mount pre-amps along with power amplifiers that are in their station. The pre-amps can't handle the RF power going out. So, sequencers are used so that when the PTT is pressed, the pre-amp is switched out of the RF path, the power amp is put into transmit mode, then the exciter is allowed to key up. When PTT is released, the exciter unkeys, the power amp goes back to stand-by, and the pre-amp is switched back into the RF path.
 

RFI-EMI-GUY

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Satellite and EME stations use these for protecting preamplifiers and transverters. It is all about sequencing the transmitter RF to lag the switching of the preamp. My IC970A station with external Mirage power amp has one built in. I modified the power amp to route the DC preamp bias around the PA using two bias tees. It works fine. Except once while using satellite mode with the station, I switched the mode off while transmitting and zapped the preamp.

Sent from my SM-T350 using Tapatalk
 
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