[TangerineSDR] TangerineSDR Digest, Vol 29, Issue 11

Ward Silver hwardsil at gmail.com
Sat Aug 21 18:07:58 EDT 2021 

Type 75 material is recommended for suppression applications from 200 kHz
to 30 MHz

https://www.fair-rite.com/product-category/suppression-components/round-cable-emi-suppression-cores/

73, Ward N0AX

On Sat, Aug 21, 2021 at 5:02 PM <tangerinesdr-request at lists.tapr.org> wrote:

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> Today's Topics:
>
>    1. Re: [HamSCI] RE: Notes from PSWS / TangerineSDR call of
>       07-26-2021 (Jonathan)
>
>
> ----------------------------------------------------------------------
>
> Message: 1
> Date: Thu, 29 Jul 2021 13:23:34 -0400
> From: Jonathan <emuman100 at gmail.com>
> To: Ward Silver <hwardsil at gmail.com>
> Cc: Julius Madey <hillfox at fairpoint.net>, hamsci
>         <hamsci at googlegroups.com>, Tom McDermott <tom.n5eg at gmail.com>,
> TAPR
>         TangerineSDR Modular Software Defined Radio
>         <tangerinesdr at lists.tapr.org>
> Subject: Re: [TangerineSDR] [HamSCI] RE: Notes from PSWS /
>         TangerineSDR call of 07-26-2021
> Message-ID: <29865318-FCCB-4A1E-B3DB-EFF738A19F04 at gmail.com>
> Content-Type: text/plain; charset="utf-8"
>
> Phil,
>
> Thanks for letting me know. I?ll reach out to Earle for more information.
>
> Ward,
>
> Thank you for that reminder and the great design tip. The feedline I will
> be using is shielded CAT6. One pair carries DC power and the other carries
> VLF audio. I plan on grounding the shield too.
>
> Jules,
>
> Would mix 31 be appropriate for VLF? It looks like it?s recommended for a
> frequency range of 1-300MHz, so it that case, it should eliminate any of
> those high frequency transients from EFT? They can?t be installed in the
> conduit, but can be installed on the feedline coming into the Raspberry Pi
> box.
>
>
>
> Thanks.
>
> Jonathan
>
> KC3EEY
>
>
> > On Jul 28, 2021, at 4:46 PM, Ward Silver <hwardsil at gmail.com> wrote:
> >
> > Blocking common-mode RF current using ferrite chokes is a good
> technique.  So is using shielded cable for everything and metal enclosures
> bonded together.  Jim has several tutorials about this available on his web
> page (k9yc.com/publish.htm) - see the slide show about reducing received
> noise.  This was an evolution of a presentation on common-mode chokes (
> http://www.yccc.org/Articles/W1HIS/CommonModeChokesW1HIS2006Apr06.pdf) by
> Chuck Counselman, W1HIS in the context of reduced received noise. (The
> presentation was created before Type 31 ferrite became available which is a
> much better material for EMI suppression.)
> >
> > 73, Ward N0AX
> >
> >       Virus-free. www.avast.com
> >
> >> On Wed, Jul 28, 2021 at 3:32 PM Julius Madey <hillfox at fairpoint.net>
> wrote:
> >> On that note, I wonder if it would be a good idea to put a common mode
> choke (multiple turns of the power feed line through an appropriate ferrite
> mix)  in the line ?  K9YC's audio RFI paper is a good reference.
> >> 73,
> >> Jules-K2KGJ
> >>
> >>> On 7/28/2021 4:02 PM, Ward Silver wrote:
> >>> A quick note - rectifiers, LEDs, or any non-linear devices connected
> to unshielded cables of any significant length will happily act as mixers
> or harmonic generators.  Whenever one of these is used, put a 0.01uF disc
> ceramic across it to bypass it at RF.
> >>>
> >>> 73, Ward N0AX
> >>>
> >>>     Virus-free. www.avast.com
> >>>
> >>>> On Wed, Jul 28, 2021 at 11:41 AM Jonathan <emuman100 at gmail.com>
> wrote:
> >>>> Hi Tom,
> >>>>
> >>>> That makes a lot of sense. I?ll try fit a 0.1uF and a 22-47uF
> electrolytic on the feedline loop.
> >>>>
> >>>> Thanks again!
> >>>>
> >>>> Jonathan
> >>>> KC3EEY
> >>>>
> >>>> On Jul 28, 2021, at 10:55 AM, Tom McDermott <tom.n5eg at gmail.com>
> wrote:
> >>>>
> >>>>> Hi Jonathan - a concern is that the DC-DC converter input stage
> would become unstable and oscillate
> >>>>> with the cable inductance.  If that happens then there could be high
> frequency AC voltages present at the
> >>>>> input of the converter.  Would those over-voltage the input?
> Possibly.   Would it radiate RFI from the cable?  Likely.
> >>>>>
> >>>>> Good design dictates sufficiently low source impedance to the DC-DC
> converter.  Almost all linear regulators
> >>>>> require it.  An electrolytic and ceramic bypass pair right at the
> DC-DC input would be considered good design by many.
> >>>>>
> >>>>> -- Tom, N5EG
> >>>>>
> >>>>>
> >>>>>
> >>>>>
> >>>>>
> >>>>>
> >>>>>> On Wed, Jul 28, 2021 at 7:30 AM Jonathan <emuman100 at gmail.com>
> wrote:
> >>>>>> John,
> >>>>>>
> >>>>>> Thanks for the suggestion! I think I?ll start with the overvoltage
> age spike of 50V for 100ms or less based on the datasheet spec of the DC-DC
> converter. I was thinking of some sort of fusable circuit protection now
> that I?ll be using a TVS diode to mitigate stress from the follow current.
> >>>>>>
> >>>>>>
> >>>>>>
> >>>>>> Tom,
> >>>>>>
> >>>>>> The datasheet wasn?t clear on the need for input filtering. On the
> output of both the IP2415S, I have 0.1uF ceramic capacitors. In the
> datasheet, it only mentions a spec of ?Input Reflected Rated Current? with
> a series inductor and shunt capacitor. I don?t really understand exactly
> what this is, but it lists ?20mAp-p through a 12uH inductor and 47uF
> capacitor?. Nothing else is mentioned about input protection or filtering.
> >>>>>>
> >>>>>> In both situations that the DC-DC failed, the
>      cable length was only 4? of cat 5. This circuit that was proved and
> tested by Paul, including the receiver and schematic I attached, did not
> have such an issue, but the only difference is that the voltage was lower
> than 30V. That?s why I was thinking it was a turn-on/off spike. I think
> that in a lot of typical applications, the input voltage isn?t that high,
> so spikes don?t normally present a problem. The DC-DC that feeds the
> receiver DC-DC has never failed and it was always fed with 18V or less.
> >>>>>>
> >>>>>>
> >>>>>>
> >>>>>> Jules,
> >>>>>>
> >>>>>> You recommend the Schottky diode in parallel with the TVS, then a
> series PTC, so during a spike, the TVS will conduct and the PTC would fuse,
> and during a reverse polarity condition, the Schottky diode will conduct
> with limited current due to the PTC fusing? I can see the benefit that the
> series PTC in normal a normal circuit condition would drop much less
> voltage that the Schottky diode.
> >>>>>>
> >>>>>>
> >>>>>>
> >>>>>> All in all, I agree with adding some capacitance to filter voltage
> spikes and reduce or eliminate them. I?ll need to be sure not to exceed the
> DC-DC max load capacitance, which is 47uF in this case.
> >>>>>>
> >>>>>> But, to me, the most plausible cause for the failures are turn
> on/off voltage spikes, even with a short length of cable. Adding
> electrolytics is a bit difficult due to the tight space constraint as seen
> in my previous email, so I?ll try out the TVS and a PTC. Other than voltage
> spikes, does anything else come to mind?
> >>>>>>
> >>>>>>
> >>>>>>
> >>>>>> Thanks guys.
> >>>>>>
> >>>>>> Jonathan
> >>>>>>
> >>>>>> KC3EEY
> >>>>>>
> >>>>>>
> >>>>>>> On Tue, Jul 27, 2021 at 9:34 AM Jonathan <emuman100 at gmail.com>
> wrote:
> >>>>>>> Hi Everyone,
> >>>>>>>
> >>>>>>> Before the meeting ended last night, I wanted to discuss the
> issues I?ve experienced with my VLF active antenna. As I mentioned, the
> DC-DC converter (XP Power IP2415S) failed after I applied power. I turned
> the volume up because I wasn?t hearing sferics, and shortly after, I heard
> the squeal of the DC-DC converter. When I pulled out the smaller foam core
> partially, I heard a squeal coming from the DC-DC converter itself.
> >>>>>>> <image3.jpeg>
> >>>>>>>
> >>>>>>> I had a failure of the DC-DC converter when I first built the VLF
> preamp. It was being powered by the Raspberry Pi box (same power circuit as
> my text box). I had a power failure and when the power was restored, the
> DC-DC converter failed.  In both situations, it was being supplied with
> 30VDC, with the limit is 36V. The reason for using 30V is to overcome the
> voltage drop from long cable lengths.
> >>>>>>>
> >>>>>>> After both failures, there was a low impedance across the input of
> the DC-DC converter causing the supply to be pulled down. Because the input
> and output are isolated, I figured the fault had to have been caused by a
> voltage spike on the input due to power being turned on and off. The
> datasheet mentions that it can withstand 50V spikes at 100ms, but I can?t
> think of anything else that could cause the DC-DC to fail, especially that
> 30V is used to power it and any voltage spike would ride on top of that
> 30V. I contacted XP Power about the issue.
> >>>>>>>
> >>>>>>> Here is the schematic of the power path. The blocks are the
> IP2415S DC-DC converter.
> >>>>>>>
> >>>>>>> I?m powering the DC-DC converter with 30V from another DC-DC
> converter in the test box and Raspberry Pi box (Raspberry Pi box not shown,
> but same circuit). Keep in mind, the length is still relatively short in my
> testing, so cable inductance isn?t the primary reason for the spike. Plus,
> at long lengths, the voltage would be much lower due to voltage drop across
> the length, and I think this was why Paul might not have seen this issue
> when he originally tried and built this design.
> >>>>>>>
> >>>>>>> To mitigate this problem with the supply voltage at 30V, I decided
> to use a TVS diode across the input of the DC-DC converter. Here is the
> schematic: (my apologies for the TVS diode being backwards)
> >>>>>>>
> >>>>>>> I chose a unidirectional TVS so there is also protection if the
> voltage spikes have any negative components. I picked a TVS with a working
> voltage of 33V, a Littel Fuse P4KE39A. According to the datasheet, it looks
> like this would be adequate. TVS diodes have a PN junction that is more
> rugged, with a larger surface area for greater current density. One thing I
> overlooked with this type of circuit protection is that once the TVS
> conducts, current from the power supply will be shunted too, known as the
> follow current, and in some situations, this may cause issues requiring a
> fuse. In this case, since the spikes are probably short duration, and since
> the DC-DC converter in the text/Pi box has short circuit protection, this
> should not be an issue.
> >>>>>>>
> >>>>>>> So the questions I have are: do you also think it could be voltage
> spikes that caused the failures, and if so, was my choice of TVS diode
> adequate. Also, one important question, if I connect the anode of the TVS
> diode to the receiver side ground, will I lose
>    isolation? I know that during spike current conduction, I will. I?m sure
> I can still get adequate protection with the TVS diode anode connected to
> the negative of the isolated power loop too, but I just wanted to be sure.
> >>>>>>>
> >>>>>>> Lastly, since the magnetometer board will undergo another
> revision, I feel it may be worth it to add some sort or adjustable
> regulator or use of an external power source (not connected to the 5V pin
> of the Pi header) because even with paralleling wires or pairs, some
> installations will require very long lengths (especially since
> interference-free locations are often far away from the shack) and the
> voltage may drop to where the LDO cant regulate. Using a higher voltage at
> the Pi end (like I do with the VLF preamp) may be required for some
> installations. I think this should be considered if it already wasn?t
> addressed.
> >>>>>>>
> >>>>>>> Jonathan
> >>>>>>> KC3EEY
> >>>>>>>
> >>>>>>>
> >>>>>>>
> >>>>>>> On Jul 27, 2021, at 7:21 AM, Dr. Nathaniel A. Frissell Ph.D. <
> nathaniel.frissell at scranton.edu> wrote:
> >>>>>>>
> >>>>>>>>
> >>>>>>>>
> >>>>>>>>
> >>>>>>>>
> >>>>>>>>
> >>>>>>>>
> >>>>>>>>
> >>>>>>>>
> >>>>>>>>
> >>>>>>>>
> >>>>>>>>
> >>>>>>>>
> >>>>>>>>
> >>>>>>>>
> >>>>>>>>
> >>>>>>>>
> >>>>>>>> Thank you, Tom.
> >>>>>>>>
> >>>>>>>>
> >>>>>>>>
> >>>>>>>>
> >>>>>>>>
> >>>>>>>>
> >>>>>>>>
> >>>>>>>> The recording will be available later today at
> >>>>>>>>
> >>>>>>>> https://youtu.be/AammohuygMw and hamsci.org/telecons.
> >>>>>>>>
> >>>>>>>>
> >>>>>>>>
> >>>>>>>>
> >>>>>>>>
> >>>>>>>>
> >>>>>>>>
> >>>>>>>> 73 de Nathaniel W2NAF
> >>>>>>>>
> >>>>>>>>
> >>>>>>>>
> >>>>>>>>
> >>>>>>>>
> >>>>>>>>
> >>>>>>>>
> >>>>>>>>
> >>>>>>>>
> >>>>>>>> From: TangerineSDR <tangerinesdr-bounces at lists.tapr.org>
> >>>>>>>>
> >>>>>>>> On Behalf Of Tom McDermott via TangerineSDR
> >>>>>>>>
> >>>>>>>>
> >>>>>>>> Sent: Monday, July 26, 2021 10:02 PM
> >>>>>>>>
> >>>>>>>>
> >>>>>>>> To: TAPR TangerineSDR Modular Software Defined Radio <
> tangerinesdr at lists.tapr.org>
> >>>>>>>>
> >>>>>>>>
> >>>>>>>> Cc: Tom McDermott <tom.n5eg at gmail.com>
> >>>>>>>>
> >>>>>>>>
> >>>>>>>> Subject: [TangerineSDR] Notes from PSWS / TangerineSDR call of
> 07-26-2021
> >>>>>>>>
> >>>>>>>>
> >>>>>>>>
> >>>>>>>>
> >>>>>>>>
> >>>>>>>>
> >>>>>>>>
> >>>>>>>>
> >>>>>>>>
> >>>>>>>>
> >>>>>>>>
> >>>>>>>>
> >>>>>>>>
> >>>>>>>>
> >>>>>>>>
> >>>>>>>>
> >>>>>>>>
> >>>>>>>>
> >>>>>>>>
> >>>>>>>>
> >>>>>>>>
> >>>>>>>>
> >>>>>>>>
> >>>>>>>> Notes from PSWS / TangerineSDR call of 07-26-2021
> >>>>>>>>
> >>>>>>>>
> >>>>>>>>
> >>>>>>>>
> >>>>>>>>
> >>>>>>>>
> >>>>>>>>
> >>>>>>>>
> >>>>>>>>
> >>>>>>>>
> >>>>>>>>
> >>>>>>>>
> >>>>>>>>
> >>>>>>>>
> >>>>>>>>
> >>>>>>>> 1. Bill is using chart.js for magnetometer charting. He is
> setting up a database using Django web and database framework for Python.
> >>>>>>>>
> >>>>>>>>
> >>>>>>>>
> >>>>>>>>
> >>>>>>>>
> >>>>>>>>
> >>>>>>>>
> >>>>>>>>
> >>>>>>>>
> >>>>>>>>
> >>>>>>>>
> >>>>>>>>
> >>>>>>>>
> >>>>>>>>
> >>>>>>>>
> >>>>>>>> 2. Scotty is looking at the Intel (Altera) Arria 10 GX FPGA
> 10GX270 for the version 2 Data Engine (supporting 10GE). These FPGAs appear
> to be more available than the MAX10 FPGAs. The intention is to develop DE
> Ver 1 and DE Ver 2 in parallel
> >>>>>>>>
> >>>>>>>> while awaiting FPGA component availability. The 10 GX development
> boards are pretty expensive.
> >>>>>>>>
> >>>>>>>>
> >>>>>>>>
> >>>>>>>>
> >>>>>>>>
> >>>>>>>>
> >>>>>>>>
> >>>>>>>>
> >>>>>>>>
> >>>>>>>>
> >>>>>>>>
> >>>>>>>>
> >>>>>>>>
> >>>>>>>>
> >>>>>>>>
> >>>>>>>> -- Tom, N5EG
> >>>>>>>>
> >>>>>>>>
> >>>>>>>>
> >>>>>>>>
> >>>>>>>>
> >>>>>>>>
> >>>>>>>>
> >>>>>>>>
> >>>>>>>>
> >>>>>>>>
> >>>>>>>>
> >>>>>>>>
> >>>>>>>>
> >>>>>>>>
> >>>>>>>>
> >>>>>>>>
> >>>>>>>>
> >>>>>>>>
> >>>>>>>>
> >>>>>>>>
> >>>>>>>>
> >>>>>>>>
> >>>>>>>>
> >>>>>>>>
> >>>>>>>>
> >>>>>>>>
> >>>>>>>>
> >>>>>>>>
> >>>>>>>>
> >>>>>>>>
> >>>>>>>>
> >>>>>>>>
> >>>>>>>>
> >>>>>>>>
> >>>>>>>>
> >>>>>>>>
> >>>>>>>>
> >>>>>>>>
> >>>>>>>>
> >>>>>>>>
> >>>>>>>>
> >>>>>>>>
> >>>>>>>>
> >>>>>>>>
> >>>>>>>>
> >>>>>>>> --
> >>>>>>>>
> >>>>>>>>
> >>>>>>>> Please follow the HamSCI Community Participation Guidelines at
> http://hamsci.org/hamsci-community-participation-guidelines.
> >>>>>>>>
> >>>>>>>>
> >>>>>>>> ---
> >>>>>>>>
> >>>>>>>>
> >>>>>>>> You received this message because you are subscribed to the
> Google Groups "HamSCI" group.
> >>>>>>>>
> >>>>>>>>
> >>>>>>>> To unsubscribe from this group and stop receiving emails from it,
> send an email to hamsci+unsubscribe at googlegroups.com.
> >>>>>>>>
> >>>>>>>>
> >>>>>>>> To view this discussion on the web visit
> https://groups.google.com/d/msgid/hamsci/SA0PR03MB5547CBF733EFEB4D829E659FF2E99%40SA0PR03MB5547.namprd03.prod.outlook.com
> .
> >>>>>>>>
> >>>>>>>>
> >>>> --
> >>>> Please follow the HamSCI Community Participation Guidelines at
> http://hamsci.org/hamsci-community-participation-guidelines.
> >>>> ---
> >>>> You received this message because you are subscribed to the Google
> Groups "HamSCI" group.
> >>>> To unsubscribe from this group and stop receiving emails from it,
> send an email to hamsci+unsubscribe at googlegroups.com.
> >>>> To view this discussion on the web visit
> https://groups.google.com/d/msgid/hamsci/59FAEE9C-11F5-4CDF-B960-2E583E42E89C%40gmail.com
> .
> >>>
> >>>
> >>>     Virus-free. www.avast.com
> >>> --
> >>> Please follow the HamSCI Community Participation Guidelines at
> http://hamsci.org/hamsci-community-participation-guidelines.
> >>> ---
> >>> You received this message because you are subscribed to the Google
> Groups "HamSCI" group.
> >>> To unsubscribe from this group and stop receiving emails from it, send
> an email to hamsci+unsubscribe at googlegroups.com.
> >>> To view this discussion on the web visit
> https://groups.google.com/d/msgid/hamsci/CAFr7d%3DqbQQj4-iEcb_wFnPzbeG6XYO1Q6RV4RhTpX0ihyFxvEQ%40mail.gmail.com
> .
> >>
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