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Is it a duplexer or diplexer that I need to work satellites with one full duplex dual band radio?

Ok. I think I just answered my own question by actually reading the article the following quote is sourced from. I’m going to post this just in case others have the same question.

TL;DR: Duplexer is the answer.

Diplexers separate signals based on frequency, whereas duplexers separate the transmit and receive path of signals based on their direction.
Source: https://resources.pcb.cadence.com/blog/2023-diplexers-vs-duplexers

The Venn diagram in the above source really brings it home. “Duplexers separate the transmit and receive path of signals based on direction”

Image source: https://content.cdntwrk.com/files/aHViPTg1NDMzJmNtZD1pdGVtZWRpdG9yaW1hZ2UmZmlsZW5hbWU9aXRlbWVkaXRvcmltYWdlXzY0YmUyMGIzODFjNjEuanBnJnZlcnNpb249MDAwMCZzaWc9ZWM0YWE3ZDQyYzQ0MDJkNzE3MzI1M2RiODVhNWNjZDU%253D

My confusion started as I was googling around and found this Reddit thread: https://www.reddit.com/r/amateurradio/comments/eq7tal/do_i_need_a_duplexer_for_satellite_work_with_a/ with answers in both directions.

OP asked “Do I need a duplexer for satellite work with a full duplex radio?”

Answers included:

“devices meant […] specifically for separating HF and VHF/UHF”

As the terminology is commonly used, that is a diplexer, not a duplexer.

Then another support for diplexer:

A duplexer (the english speaking world) is a device to combine or split RF paths for a specific frequency, generally in the same band and traditionally use cavity filtering to accomplish this. A diplexer is a device to combine or split frequency ranges of different bands and typically uses a LC filters. The designs come in arrangements of low pass/high pass (diplexer), low pass/band pass/high pass (triplexer), and various low pass/band pass/band pass/…/high pass designs (multiplexers).

The reason you see duplexer often (mistakenly) used in place of diplexer…has to due with the lack of the specific word in the language used in the country the product was manufactured in.

Then the contradiction:

Yes. You need a duplexer to send 70cm to the 70cm side and 2M to 2M.

Along with a link to build duplexers: http://k0lee.com/duplexer.php

And finally, a suggestion to buy a diplexer.

You need a diplexer. Get an MFJ-916.

But the MFJ-916 isn’t a diplexer. It’s a duplexer. https://mfjenterprises.com/products/mfj-916b

I feel like many people are misusing these terms.

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S.M.A.R.T. Goals – Achievable vs Attainable

S.M.A.R.T. goals are often interchangeably written with the A as either achievable or attainable.

Attainable is wrong.

Achievable refers to something that is capable of being accomplished, while attainable refers to something that can be reached or obtained. In other words, achievable is about possibility, while attainable is about accessibility.

The Content Authority – https://thecontentauthority.com/blog/achievable-vs-attainable

When defining goals, you are looking to remove ambiguity. Therefore the A needs to be achievable because we are interested in assessing whether or not the goal is possible. If it is not possible, then we have not written a clear goal.

S.M.A.R.T. goals are a way of setting oblectives that are clear, trackable, and achievable. S – specific; M – measurable; A – achievable; R – relevant; T – time-bound

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It’s the intention not the outcome

I found a blank journal I gave my daughter years ago. She decided not to use it and put it in our bucket of stuff to repurpose to others. In this case, I needed a blank journal so I repurposed it to me. It gave me a smile. A certain number of pages into the book, I’d written a note to my daughter. She never saw it but it made me smile twice. Once when I wrote it and again when I rediscovered it.

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Form habits

Learn something every day. It will keep you sharp. I’m lucky that my career field is constant learning. However, I supplement it with other things such as language learning. A few minutes study every day won’t make me conversational but it creates a habit which strengthens my willpower for developing other habits…such as daily exercise. For instance, I now feel guilty if I don’t do pushups first thing in the morning.