I have performed additional testing to better understand the buzz phenomena.
I fabricated a current probe that measures the current on the power supply cable and cabled it to an HP8901 modulation analyzer.? The power supply cable was intentionally routed next to the SHARI? antenna to produce a worst case situation. Pictures of the setup have been added to the Photos folder.? I found that with no ferrite filter on the power supply the AM modulation was almost 20%.? Adding 1 Laird 28B1020-100 core (similar to mix 31) with 2 turns through it reduced the modulation to less than 0.5% (essentially gone).? With the core installed, no buzz could be located for any position of the receiving HT antenna.? I also found that? curling my hand around the antenna and vary its position was a good way to test the suppression as different hand positions revealed buzzing when no ferrite was used.
I also tried a Laird split core, P/N 0431164181, with similar results
I tested both VHF and UHF and found the buzzing phenomena was worse at VHF than UHF.
I also verified that the same modulation situation occurred when I transmitted with the HT (rather than listening) which is why someone might tell you they hear buzzing on your audio.? With the ferrite, the modulation also disappeared.
The bottom line is the buzzing on both transmit and receive is being caused by the Pi power supply modulating the RF antenna current coupled onto the Pi supply power cable.? It can be eliminated with one ferrite core at the Pi power supply.? This buzzing is not caused by SHARI.? Any node with a built-in radio or the HT you are using to talk to your node can cause this to occur.
Steve - N8AR
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I used a raspberry pi 3 for my uhf repeater and vhf simplex node. I use a 12v automotive USB power outlet to power the pi 3. Once I get my SHARI-U. I'll test it out.
Thanks, David
On Sat, May 2, 2020, 6:40 AM Steve Matzura < number6@...> wrote: I find this assessment a real ear-opener. I've always been able to
detect who has a Shari node and who has something else, because almost
to a fault, those stations using a Shari have the buzz. I don't
specifically know any other kind of Allstar node that uses a Raspberry
Pi other than a homebrew one, like the one I'm building with a URI
cable, a fob, and my own radio, so after reading this, I'm thinking my
node will be subject to this problem, too, telling me it's thankfully
not due to the Shari transceiver. I'm also thinking mine might have the
problem even more than a Shari node might because it's using ten times
the power--five watts--but the antenna, a tri-band mag mount, is at
twice the distance--outside on a terrace. Definitely good information to
have when I get transceiving and discover I have the buzz, too.
Regarding the choke on the Pi power supply, the Pi 3 that runs my
hotspot has one, but unles it's built into the in-line switch, the power
supply on my 4 B? which will run my Allstar node does not. Curiouser and
curiouser.
On 5/1/2020 5:11 PM, N8AR wrote:
> Hi Quentin,
>
> I have just completed an investigation into this issue as I experience
> it here also.? I am writing a report which I will share with the
> groups in a few days.
>
> Basically the problem is caused by your Pi power supply or other
> similar wall warts in the immediate area of the SHARI antenna. What is
> happening is your SHARI is coupling RF energy into the power lead to
> the Pi from the power supply.? This energy at your chose transmit
> frequency is pulse modulated at a 60 Hz rate by the AC power rectifier
> diodes which only conduct over part of the 60 Hz cycle resulting in
> sidebands every 60 Hz (i.e. 60,120,190 ....Hz) with a sin(x/x envelope
> shape about your transmit frequency.? The radio you are using to
> listen to your node (call it an HT) receives the RF signal from your
> node plus this pulse modulated signal.? What you hear depends on the
> strength of each signal at your HT antenna? and how the FM detector in
> your HT works (especially the capture effect),? Sometimes the signal
> from SHARI wins, sometimes the modulated signal wins and most the time
> it is a combination.? You move your HT a few inches and it sounds
> fine, move it a few more and the buzz is incredible.
>
> If you have a phone recharging battery, use it to power your Pi and
> the buzz should go away if there are no other wallwarts nearby.?
> (other nearby wallwarts can cause the same problem but at a lower level)
>
> I have "debuzzed" my Pi supply by using two FT114-61 ferrites right at
> the power supply with 4 turns of the power supply lead through each
> ferrite.? This keeps most of the SHARI RF energy out of the wall wart
> and thus the sidebands are vastly lower.? ?I have some Fair-rite type
> 61 cores which should be identical to the FT114-61 cores on order from
> Digikey (much cheaper than the Amidon cores) and will test them soon.
>
> The problem can also occur on your audio that others hear as the RF
> from your HT is subject to the same problem.? The closer you get to
> your node and thus your power supply, the worse the problem.
>
> Another solution to this problem is to use an external antenna on
> SHARI so that your radiated RF is not near your Pi power supply or any
> other wallwart.
>
> I created a photo album in the photofolder showing this modulation
> phenomena.
|
My node from G7RPG has the hum, but that is usually eliminated if I listen carefully while moving it a few inches this way or that on the desk.
toggle quoted message
Show quoted text
On 5/2/2020 9:18 AM, Steve Matzura wrote: I find this assessment a real ear-opener. I've always been able to detect who has a Shari node and who has something else, because almost to a fault, those stations using a Shari have the buzz. I don't specifically know any other kind of Allstar node that uses a Raspberry Pi other than a homebrew one, like the one I'm building with a URI cable, a fob, and my own radio, so after reading this, I'm thinking my node will be subject to this problem, too, telling me it's thankfully not due to the Shari transceiver. I'm also thinking mine might have the problem even more than a Shari node might because it's using ten times the power--five watts--but the antenna, a tri-band mag mount, is at twice the distance--outside on a terrace. Definitely good information to have when I get transceiving and discover I have the buzz, too.
Regarding the choke on the Pi power supply, the Pi 3 that runs my hotspot has one, but unles it's built into the in-line switch, the power supply on my 4 B? which will run my Allstar node does not. Curiouser and curiouser.
On 5/1/2020 5:11 PM, N8AR wrote:
Hi Quentin,
I have just completed an investigation into this issue as I experience it here also.? I am writing a report which I will share with the groups in a few days.
Basically the problem is caused by your Pi power supply or other similar wall warts in the immediate area of the SHARI antenna. What is happening is your SHARI is coupling RF energy into the power lead to the Pi from the power supply.? This energy at your chose transmit frequency is pulse modulated at a 60 Hz rate by the AC power rectifier diodes which only conduct over part of the 60 Hz cycle resulting in sidebands every 60 Hz (i.e. 60,120,190 ....Hz) with a sin(x/x envelope shape about your transmit frequency.? The radio you are using to listen to your node (call it an HT) receives the RF signal from your node plus this pulse modulated signal.? What you hear depends on the strength of each signal at your HT antenna? and how the FM detector in your HT works (especially the capture effect), Sometimes the signal from SHARI wins, sometimes the modulated signal wins and most the time it is a combination.? You move your HT a few inches and it sounds fine, move it a few more and the buzz is incredible.
If you have a phone recharging battery, use it to power your Pi and the buzz should go away if there are no other wallwarts nearby.? (other nearby wallwarts can cause the same problem but at a lower level)
I have "debuzzed" my Pi supply by using two FT114-61 ferrites right at the power supply with 4 turns of the power supply lead through each ferrite.? This keeps most of the SHARI RF energy out of the wall wart and thus the sidebands are vastly lower. ?I have some Fair-rite type 61 cores which should be identical to the FT114-61 cores on order from Digikey (much cheaper than the Amidon cores) and will test them soon.
The problem can also occur on your audio that others hear as the RF from your HT is subject to the same problem.? The closer you get to your node and thus your power supply, the worse the problem.
Another solution to this problem is to use an external antenna on SHARI so that your radiated RF is not near your Pi power supply or any other wallwart.
I created a photo album in the photofolder showing this modulation phenomena.
|
I find this assessment a real ear-opener. I've always been able to detect who has a Shari node and who has something else, because almost to a fault, those stations using a Shari have the buzz. I don't specifically know any other kind of Allstar node that uses a Raspberry Pi other than a homebrew one, like the one I'm building with a URI cable, a fob, and my own radio, so after reading this, I'm thinking my node will be subject to this problem, too, telling me it's thankfully not due to the Shari transceiver. I'm also thinking mine might have the problem even more than a Shari node might because it's using ten times the power--five watts--but the antenna, a tri-band mag mount, is at twice the distance--outside on a terrace. Definitely good information to have when I get transceiving and discover I have the buzz, too.
Regarding the choke on the Pi power supply, the Pi 3 that runs my hotspot has one, but unles it's built into the in-line switch, the power supply on my 4 B? which will run my Allstar node does not. Curiouser and curiouser.
toggle quoted message
Show quoted text
On 5/1/2020 5:11 PM, N8AR wrote: Hi Quentin,
I have just completed an investigation into this issue as I experience it here also.? I am writing a report which I will share with the groups in a few days.
Basically the problem is caused by your Pi power supply or other similar wall warts in the immediate area of the SHARI antenna. What is happening is your SHARI is coupling RF energy into the power lead to the Pi from the power supply.? This energy at your chose transmit frequency is pulse modulated at a 60 Hz rate by the AC power rectifier diodes which only conduct over part of the 60 Hz cycle resulting in sidebands every 60 Hz (i.e. 60,120,190 ....Hz) with a sin(x/x envelope shape about your transmit frequency.? The radio you are using to listen to your node (call it an HT) receives the RF signal from your node plus this pulse modulated signal.? What you hear depends on the strength of each signal at your HT antenna? and how the FM detector in your HT works (especially the capture effect),? Sometimes the signal from SHARI wins, sometimes the modulated signal wins and most the time it is a combination.? You move your HT a few inches and it sounds fine, move it a few more and the buzz is incredible.
If you have a phone recharging battery, use it to power your Pi and the buzz should go away if there are no other wallwarts nearby.? (other nearby wallwarts can cause the same problem but at a lower level)
I have "debuzzed" my Pi supply by using two FT114-61 ferrites right at the power supply with 4 turns of the power supply lead through each ferrite.? This keeps most of the SHARI RF energy out of the wall wart and thus the sidebands are vastly lower.? ?I have some Fair-rite type 61 cores which should be identical to the FT114-61 cores on order from Digikey (much cheaper than the Amidon cores) and will test them soon.
The problem can also occur on your audio that others hear as the RF from your HT is subject to the same problem.? The closer you get to your node and thus your power supply, the worse the problem.
Another solution to this problem is to use an external antenna on SHARI so that your radiated RF is not near your Pi power supply or any other wallwart.
I created a photo album in the photofolder showing this modulation phenomena.
|
Thank you for the in-depth and very fast answer. Much appreciated ! I'll try some of the above and report back once I find a good home for the SHARI, away from all the internet router and everything else that's likely contributing.
|
If I understood the question right, yes I've experienced that as well on my units.I found that putting a ferrite on the USB power cable and Ethernet cable seems to resolve the issue.??
Hi all,
I got my SHARI in the mail last week, and it's up and running as of this morning. I really like the build quality and the clear, detailed instructions.
When I connect to my local repeater's AllStar node for testing, I receive a hum or buzz on RX similar to what you might hear with power supply problems. Others tell me that my TX has a hum or buzz that starts quiet but gets very loud. Has anyone experienced anything like this, and have thoughts on what might be causing it ?
Thanks so much. 73 de K7DRQ.
|
Hi Quentin,
I have just completed an investigation into this issue as I experience it here also.? I am writing a report which I will share with the groups in a few days.
Basically the problem is caused by your Pi power supply or other similar wall warts in the immediate area of the SHARI antenna.? What is happening is your SHARI is coupling RF energy into the power lead between the Pi and the wall wart power supply.? This energy at your chosen transmit frequency is pulse modulated at a 60 Hz rate by the Pi power supply AC power rectifier diodes which only conduct over part of the 60 Hz cycle resulting in sidebands every 60 Hz (i.e. 60,120,190 ....Hz) with a sin(x/x envelope shape about your transmit frequency.? The radio you are using to listen to your node (call it an HT) receives the RF signal from your node plus this pulse modulated signal.? What you hear depends on the strength of each signal at your HT antenna? and how the FM detector in your HT works (especially the capture effect),? Sometimes the signal from SHARI wins, sometimes the modulated signal wins and most of the time it is a combination.? You move your HT a few inches and it sounds fine, move it a few more and the buzz is incredible.
If you have a phone recharging battery, use it to power your Pi and the buzz should go away if there are no other wallwarts nearby.? (other nearby wall warts can cause the same problem but at a lower level)
I have "debuzzed" my Pi supply by using two FT114-61 ferrites right at the power supply with 4 turns of the power supply lead through each ferrite.? This keeps most of the SHARI RF energy out of the wall wart and thus the sidebands are vastly lower.? ?I have some Fair-rite type 61 cores which should be identical to the FT114-61 cores on order from Digikey (much cheaper than the Amidon cores) and will test them soon.
[Note: We are now supplying a split core ferrite (Laird part number?28A2029-0A2) with each SHARI PiXX or PiHat.? Proper installation of the ferrite is contained in the applicable construction procedure located in the Files section of this group.]
The problem can also occur on your audio that others hear as the RF from your HT is subject to the same problem.? The closer you get to your node and thus your power supply, the worse the problem.
Another solution to this problem is to use an external antenna on SHARI so that your radiated RF is not near your Pi power supply or any other wall wart.
I created a photo album in the Photos section of this group showing this modulation phenomena.
|
Hi all,
I got my SHARI in the mail last week, and it's up and running as of this morning. I really like the build quality and the clear, detailed instructions.
When I connect to my local repeater's AllStar node for testing, I receive a hum or buzz on RX similar to what you might hear with power supply problems. Others tell me that my TX has a hum or buzz that starts quiet but gets very loud. Has anyone experienced anything like this, and have thoughts on what might be causing it ?
Thanks so much. 73 de K7DRQ.
|
Thanks. That is what I was looking for. Ordered a couple of short USB extension cables. Now if I just had the SHARI...
|
Thanks. I have tried to find a power bank that will run and charge at the same time, but have been unsuccessful. I have a drawer full to prove it!
Do you have the brand or a link for one like you have?
Thanks
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Re: question on 818 settings
The settings are on pages 12 and 13 of the SHARI Allstar Node Setup Procedure in the Files section of this group.? There is also a document on "Setting the RX Level in HamVOIP Allstar in the Files section.
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I have a new Shari 3U set up and running. It¡¯s quite impressive and was very easy to set up. The next step here is configuring better audio settings. I have the recommended settings for the Allstar side but before changing levels there, are there recommended initial settings for the Shari radio itself? The 818-prog program asks for squelch, volume, enable pre-emphasis, enable high pass filter, and enable low pass filter. I looked through the documentation but didn¡¯t find any mention of those 818 settings. Can anyone share a pointer to a document or share recommended settings? Thanks. ? 73 Jim KY2D ?
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Battery will run a day half continuous.??
No special treatment done to conserve battery. I also like this battery as yuou can charge it while powered up . So I can charge during day while working . I also plug my mmdvm into the other usb and have a complete go setup.?
On Thu, Apr 30, 2020, 2:05 PM N8AR < n8ar73@...> wrote: Very cool.? How long does a battery pack last.? Did you do any special configuration of the Pi to reduce its power requirements?
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Very cool.? How long does a battery pack last.? Did you do any special configuration of the Pi to reduce its power requirements?
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One of my setups stacked on a battery pack?
On Thu, Apr 30, 2020, 12:34 PM Paul Byers < phbyers@...> wrote: I am looking forward to receiving my SHARI. In the meantime, I have been thinking of ways to reduce the footprint of the rpi and the SHARI. My thought is to hardware 2 usb cables in place of the usb connectors and flip the board so it sits over the rpi. Has anyone done this or can think of a reason not to? Thanks.
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Members of the Livingston Amateur Radio Klub (LARK) mounted the Pi on top of SHARI and used two short M/F USB extension cables. See the attached photo.
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I am looking forward to receiving my SHARI. In the meantime, I have been thinking of ways to reduce the footprint of the rpi and the SHARI. My thought is to hardware 2 usb cables in place of the usb connectors and flip the board so it sits over the rpi. Has anyone done this or can think of a reason not to? Thanks.
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I was unable to upload pictures. Don't know why. I did email them to Steve.. Hopefully they will be posted soon. In another groups.io I own (W?VFW) I am able to post pictures with messages.
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Added 3 1000 word photo's to PHOTO area.
#1 - SA818 soldering jig.
#2 - Smoke Test 5.03V
#3 - Smote Test 0.14A.
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Re: programming DCS in to shari
I have not used DCS but according to the table in the SA818 programming manual, I believe you would enter 025I (ends in the letter I not 1) for the bit pattern of 540F6B(HEX).? If you want the inverted bit pattern you enter 025N.
Steve - N8AR
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Steve-N8AR
Larry Macionski