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Author Topic: Your best clear spots in the 22 m ISM Band?  (Read 347 times)

Offline Ed H

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Your best clear spots in the 22 m ISM Band?
« on: September 05, 2018, 1940 UTC »
Hi Folks,
It occurred to me that it would be a good idea to share the quietest listening spots in the 13553-13567 ISM allocation we know and love as the HiFER band.

My reasoning for this is more or less obvious - Where is a good spot to put one's beacon, if trying to reach a particular area?

For my QTH in the SF bay area, the only spot with consistent interference is 13560 - 13562 (as tuned in USB with a typical 2.2 kHz filter). Ergo, I can easily listen from the lower portion of the band, up to about 13,559 before whistles and bleeps interfere with hearing, or the AGC kicks into action. Using a Spectrum Lab, this can be pushed a little further. On the high side, 13,562 kHz up is all quiet.

I would be interested to hear from other beaconeers on their local conditions.

Cheers

Ed

Offline Exo

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Re: Your best clear spots in the 22 m ISM Band?
« Reply #1 on: September 05, 2018, 2205 UTC »
ISM band (HiFer) : 13553 kHz to 13567 kHz

There is much less interference in the 3 kHz windows near the edges at the bottom and top:
13553.2 kHz to 13556.2 kHz is good.
13563.8 kHz to 13566.8 kHz is good.

The centre of the band at 13560 kHz +/- 3 kHz has by far the most interference:
13557 kHz to 13563 kHz is statistically the worst.

13.56 MHz is one of the most common laboratory, medical, and industrial plasma frequencies. The centre frequency, 13560 kHz, is populated worldwide by thousands of kiloWatt-level transmitters for MRI, NMR, semiconductor plasma ion deposition and sputtering chambers, industrial plasma, plasma arc, etc.

Luckily, most of those high power devices are within RF shield rooms or shielded chambers. But, even a little bit of leakage from a kiloWatt device in a screen room could easily compete with Part 15 HiFer beacons, especially when the propagation is favorable. 

RFIDs on 13.56 MHz don't usually cause much interference.

A quick survey of 13560 kHz on some of the better SNR remote SDRs provides an easy way to check the HiFer interference landscape.

« Last Edit: September 05, 2018, 2310 UTC by Exo »
Exo
HF aficionado. On the coast of northern California.
Various receivers, transceivers, and broadband antennas.
kiwiSDR receiver on private LAN for multi-freq HF monitoring.

Offline ke8dnu

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Re: Your best clear spots in the 22 m ISM Band?
« Reply #2 on: September 05, 2018, 2209 UTC »
I will at some point move my transmitter to a different frequency, but as of right now I am at 13.561.6. I do hear the qrm at 560-561 at my end but from 553 to 559.3 and 561.5 to about 566 ia usually pretty good for me when listening on both my 80m ocf and 30 m dipoles!
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Offline Ed H

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Re: Your best clear spots in the 22 m ISM Band?
« Reply #3 on: September 06, 2018, 0040 UTC »
I would expect the band centre to have the most issues... Equipment using this frequency is likely crystal controlled, and 13.56 crystals are likely to be relatively well clustered around centre.

I'm considering moving my beacon frequency, but need to implement a different frequency source than the crystal which has limited pull range. It's worth figuring out what the better spots will be in the band.

Using web SDR is a great idea to do some surveying myself. Not so many of the ones I have found provide full HF coverage, but a few allow reception of 22 m.

Thanks

Ed

Offline ke8dnu

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Re: Your best clear spots in the 22 m ISM Band?
« Reply #4 on: September 06, 2018, 0045 UTC »
I'm curious if the band has just not been behaving well or if I truly am not getting out as well as I had hoped?
20 meters hasn't been great for me lately either, so I suppose my beacon probably is just fighting conditions as they are?

Which SDR do you recommend for 22 meters, Ed?
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Offline ChrisSmolinski

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Re: Your best clear spots in the 22 m ISM Band?
« Reply #5 on: September 06, 2018, 1025 UTC »
Generally the only interference I get is centered on 13560, there's a repetitive pulsing signal there. It's only a problem within roughly a 1 kHz region.

22 and 20 meter reception has been poor here the last week or two. I've not heard any beacons, and while I run my SSTV decoding app 24 hrs on 14230, there's been far less received than earlier.
Chris Smolinski
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Offline Ed H

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Re: Your best clear spots in the 22 m ISM Band?
« Reply #6 on: September 06, 2018, 1714 UTC »
Thanks again for the feedback everyone.

Exo - your pic did not appear the first time I came back to the thread, but that is a great illustration, and very similar to what I experience along with others.

I also posted this at the LWCA message board, and I'll share what comes back.

Cheers,

Ed

Offline TickingMind

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Re: Your best clear spots in the 22 m ISM Band?
« Reply #7 on: September 07, 2018, 0003 UTC »
How far has one been able to pull a Black Cat 22m beacon (and how?)
I've been able to pull it up slightly, but it seems as to be expected the addition of caps brings the freq down into the QRM zone.
Perhaps a thread for another discussion but found it fitted in some way / context.
The Ultimate 3 I have is obviously not an issue, but as previously mentioned in this thread, crystal controlled devices seem to be clustered.
Would be interesting to hear other thoughts on this

Jason AKA TickingMind
Beacon J1LPB

Offline Ed H

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Re: Your best clear spots in the 22 m ISM Band?
« Reply #8 on: September 09, 2018, 2221 UTC »
You are welcome to discuss the frequency pulling question on this thread. It is all connected :)

I moved PVC to a new temporary frequency using the generator. It is a simple switch press on the transmitter to go back to the crystal at 13,558.4 kHz

Prizes for correct answers to "What frequency is PVC on today"

Cheers

Ed

Offline TickingMind

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Re: Your best clear spots in the 22 m ISM Band?
« Reply #9 on: September 13, 2018, 2057 UTC »
You are welcome to discuss the frequency pulling question on this thread. It is all connected :)

I moved PVC to a new temporary frequency using the generator. It is a simple switch press on the transmitter to go back to the crystal at 13,558.4 kHz

Prizes for correct answers to "What frequency is PVC on today"

Cheers

Ed

Very weak but I started to hear some chirps on 13,563.760. Never noticed them before, a little too weak to make anything out (yet) but keeping the decoder on it when not watching. Maybe it's you????  ;)

Offline Ed H

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Re: Your best clear spots in the 22 m ISM Band?
« Reply #10 on: September 16, 2018, 0520 UTC »
Thanks for the report. However, this is not the present frequency for PVC. Keep trying :)