External antenna...???

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G8OGJ
Posts: 27
Joined: Mon May 06, 2019 8:13 pm
Location: Matlock
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External antenna...???

Post by G8OGJ » Sun Sep 29, 2019 12:19 pm

Anyone got a clear reason why these small hotspots should not be used with an external antenna?

Is this an emissions issue or a licensing issue?

If the former, I have a 70cm cavity that would be quite a narrow filter and clean up any significant in-band and all out of band spurious emissions so would that do?

There is quite a lot of local screening where I live and a few mW to a 6dBi antenna atop the house might enable me to work in the local pub but no further...

Ian
Amateur Radio Station G8OGJ

KE7FNS
Posts: 378
Joined: Wed Apr 17, 2019 11:11 pm

Re: External antenna...???

Post by KE7FNS » Tue Oct 01, 2019 12:05 am

Well, nobody seems to be responding so I'll just throw in my two cents.

I'd say that the main reason it is frowned upon is due to spurious emissions, from what I understand these radio chips are extremely noisy spewing harmonics all over the spectrum. I'd think that if you hooked it up to a service monitor and made sure it wasn't causing any interference it wouldn't be an issue, but I don't know if that is even possible.
All views, comments, posts and opinions shared are entirely my own.

G8OGJ
Posts: 27
Joined: Mon May 06, 2019 8:13 pm
Location: Matlock
Contact:

Re: External antenna...???

Post by G8OGJ » Tue Oct 01, 2019 3:31 pm

Thanks for the reply - yes, there is not sufficient room for even a nasty ceramic filter on the board so that is a sensible deduction.

I have a spare cavity which should cover such out of band emissions - one of three formerly used in a repeater diplexer. I'd presume that the 50dB bandwidth is around 1.6MHz based on the previous application - I can test that roughly with my antenna analyser.

So unless there are any further updates, I think that my old cavity will be due for a polish! I'll bet that its lower loss than many smaller devices too!

I'll ensure that the Tx timeout is set so that it doesn't sit up all night jamming an obscure channel on its own for good measure.

Ian
Amateur Radio Station G8OGJ

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