<div dir="ltr"><div>Recent editions of the Handbook offer several polarity protection circuits in the Power Sources chapter (Chapter 7). Some of them use P-channel MOSFETS that have much lower forward voltage drops than standard diodes, even Schottky barrier diodes.</div><div><br></div><div>Regarding common-mode chokes, I think it is better to determine the need first - what frequency range and amplitude, for example - and then select a type of choke to do the job. For example, blocking RF common-mode at VLF, HF, and VHF/UHF requires different ferrite mixes and the number of turns also makes a difference in the choke's peak rejection range. (See Chapter 5 - RF Techniques - of recent Handbook editions. Much of this was written by K9YC and comes from his tutorials.)</div><div><br></div><div>I realize the original post was about power supply failures and not RFI but nothing like a good digression :-) Analog Devices also just published a couple of articles about protecting inputs for low-power interfaces in the Analog Dialogue - a little Googling will find the recent issues which are free and public. All good stuff.</div><div><br></div><div>73, Ward N0AX</div><br><div class="gmail_quote"><div dir="ltr" class="gmail_attr">On Wed, Jul 28, 2021 at 7:54 PM <<a href="mailto:tangerinesdr-request@lists.tapr.org">tangerinesdr-request@lists.tapr.org</a>> wrote:<br></div><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex"><br> Jonathan,<br>
You can use a standard silicon diode like the 1N4000 series (1A rating) <br>
for the polarity protection diode unless you want to clamp the reverse <br>
voltage at less than 0.7-0.8 volts, in which case a Schottky will <br>
provide a lower clamping voltage.? Since the reverse protection diode <br>
will clamp reverse transients, you don't need a bidirectional TVS.<br>
Jules<br>
<br>
<br>
On 7/28/2021 3:16 PM, Jonathan wrote:<br>
> Phil,<br>
><br>
> This design (Integrated VLF antenna/preamp in PVC pipe with Raspberry <br>
> Pi box) was used for an MIT study and the author of vlfrx-tools built <br>
> a bunch of these antennas and boxes for those conducting the study. <br>
> This was in 2018. Since this might have fallen under your umbrella, <br>
> did you hear of it or know who the PI might be? The DC-DC converter <br>
> has an operating frequency of 100-600 kHz, so it doesn?t really affect <br>
> anything below that. Paul really liked the performance of his design. <br>
> He even wrote a guide on how to set up the Radpberry Pi as a VLF SDR <br>
> using his vlfrx-tools software.<br>
><br>
> Jules,<br>
><br>
> I really appreciate the supplied schematic. Should I use the Schottky <br>
> diode where you drew the regular diode, in parallel like you said? I <br>
> could also probably solder the MLCC across the leads of the <br>
> electrolytic and install it. Also, that TVS is bidirectional. Should a <br>
> unidirectional TVS be used so it clips any negative spikes closer to 0V?<br>
><br>
> David,<br>
><br>
> Tom mentioned the same. I?ll be working on trying to fit an <br>
> electrolytic and a ceramic capacitor.<br>
><br>
> Khan,<br>
><br>
> This is good news. Email me if you have issues.<br>
><br>
> Jonathan<br>
> KC3EEY<br>
><br>
><br>
><br>
> On Jul 28, 2021, at 2:27 PM, Julius Madey <<a href="mailto:hillfox@fairpoint.net" target="_blank">hillfox@fairpoint.net</a> <br>
> <mailto:<a href="mailto:hillfox@fairpoint.net" target="_blank">hillfox@fairpoint.net</a>>> wrote:<br>
><br>
>> Jonathan,<br>
>> I still think you need to get rid of the series polarity protection <br>
>> diode and suggest the following schematic (with 22uf 50 volt Aluminum <br>
>> electrolytic)<br>
>><br>
>><br>
>> <eaeficdplljflikc.png><br>
>><br>
>> The PTC poly fuse will open either on overload, sustained voltage <br>
>> above TVS rating or reverse polarity.? This will also snub transients <br>
>> on the line the series diode may have permitted.? There might be some <br>
>> virtue in adding an MLCC cap of ~ 0.47uf in parallel with the <br>
>> electrolytic for lower overall ESR.<br>
>><br>
>> Regards,<br>
>> Jules-K2KGJ<br>
>><br>
>><br>
>><br>
>><br>
>><br>
>><br>
>> On 7/28/2021 12:41 PM, Jonathan wrote:<br>
>>> Hi Tom,<br>
>>><br>
>>> That makes a lot of sense. I?ll try fit a 0.1uF and a 22-47uF <br>
>>> electrolytic on the feedline loop.<br>
>>><br>
>>> Thanks again!<br>
>>><br>
>>> Jonathan<br>
>>> KC3EEY<br>
>>><br>
>>> On Jul 28, 2021, at 10:55 AM, Tom McDermott <<a href="mailto:tom.n5eg@gmail.com" target="_blank">tom.n5eg@gmail.com</a> <br>
>>> <mailto:<a href="mailto:tom.n5eg@gmail.com" target="_blank">tom.n5eg@gmail.com</a>>> wrote:<br>
>>><br>
>>>> Hi Jonathan - a concern is that the DC-DC converter input stage <br>
>>>> would become unstable and oscillate<br>
>>>> with the cable inductance.? If that happens then there could be <br>
>>>> high frequency AC voltages present at the<br>
>>>> input of the converter.? Would those over-voltage the input?? <br>
>>>> Possibly.?? Would it radiate RFI from the cable?? Likely.<br>
>>>><br>
>>>> Good design dictates sufficiently low source impedance to the DC-DC <br>
>>>> converter.? Almost all linear regulators<br>
>>>> require it.? An electrolytic and ceramic bypass pair right at the <br>
>>>> DC-DC input would be considered good design by many.<br>
>>>><br>
>>>> -- Tom, N5EG<br>
>>>><br>
>>>><br>
>>>><br>
>>>><br>
>>>><br>
>>>><br>
>>>> On Wed, Jul 28, 2021 at 7:30 AM Jonathan <<a href="mailto:emuman100@gmail.com" target="_blank">emuman100@gmail.com</a> <br>
>>>> <mailto:<a href="mailto:emuman100@gmail.com" target="_blank">emuman100@gmail.com</a>>> wrote:<br>
>>>><br>
>>>> John,<br>
>>>><br>
>>>> Thanks for the suggestion! I think I?ll start with the<br>
>>>> overvoltage age spike of 50V for 100ms or less based on the<br>
>>>> datasheet spec of the DC-DC converter. I was thinking of some<br>
>>>> sort of fusable circuit protection now that I?ll be using a TVS<br>
>>>> diode to mitigate stress from the follow current.<br>
>>>><br>
>>>><br>
>>>> Tom,<br>
>>>><br>
>>>> The datasheet wasn?t clear on the need for input filtering. On<br>
>>>> the output of both the IP2415S, I have 0.1uF ceramic<br>
>>>> capacitors. In the datasheet, it only mentions a spec of ?Input<br>
>>>> Reflected Rated Current? with a series inductor and shunt<br>
>>>> capacitor. I don?t really understand exactly what this is, but<br>
>>>> it lists ?20mAp-p through a 12uH inductor and 47uF capacitor?.<br>
>>>> Nothing else is mentioned about input protection or filtering.<br>
>>>><br>
>>>> In both situations that the DC-DC failed, the cable length was<br>
>>>> only 4? of cat 5. This circuit that was proved and tested by<br>
>>>> Paul, including the receiver and schematic I attached, did not<br>
>>>> have such an issue, but the only difference is that the voltage<br>
>>>> was lower than 30V. That?s why I was thinking it was a<br>
>>>> turn-on/off spike. I think that in a lot of typical<br>
>>>> applications, the input voltage isn?t that high, so spikes<br>
>>>> don?t normally present a problem. The DC-DC that feeds the<br>
>>>> receiver DC-DC has never failed and it was always fed with 18V<br>
>>>> or less.<br>
>>>><br>
>>>><br>
>>>> Jules,<br>
>>>><br>
>>>> You recommend the Schottky diode in parallel with the TVS, then<br>
>>>> a series PTC, so during a spike, the TVS will conduct and the<br>
>>>> PTC would fuse, and during a reverse polarity condition, the<br>
>>>> Schottky diode will conduct with limited current due to the PTC<br>
>>>> fusing? I can see the benefit that the series PTC in normal a<br>
>>>> normal circuit condition would drop much less voltage that the<br>
>>>> Schottky diode.<br>
>>>><br>
>>>><br>
>>>> All in all, I agree with adding some capacitance to filter<br>
>>>> voltage spikes and reduce or eliminate them. I?ll need to be<br>
>>>> sure not to exceed the DC-DC max load capacitance, which is<br>
>>>> 47uF in this case.<br>
>>>><br>
>>>> But, to me, the most plausible cause for the failures are turn<br>
>>>> on/off voltage spikes, even with a short length of cable.<br>
>>>> Adding electrolytics is a bit difficult due to the tight space<br>
>>>> constraint as seen in my previous email, so I?ll try out the<br>
>>>> TVS and a PTC. Other than voltage spikes, does anything else<br>
>>>> come to mind?<br>
>>>><br>
>>>><br>
>>>> Thanks guys.<br>
>>>><br>
>>>> Jonathan<br>
>>>><br>
>>>> KC3EEY<br>
>>>><br>
>>>><br>
>>>> On Tue, Jul 27, 2021 at 9:34 AM Jonathan <<a href="mailto:emuman100@gmail.com" target="_blank">emuman100@gmail.com</a><br>
>>>> <mailto:<a href="mailto:emuman100@gmail.com" target="_blank">emuman100@gmail.com</a>>> wrote:<br>
>>>><br>
>>>> Hi Everyone,<br>
>>>><br>
>>>> Before the meeting ended last night, I wanted to discuss<br>
>>>> the issues I?ve experienced with my VLF active antenna. As<br>
>>>> I mentioned, the DC-DC converter (XP Power IP2415S) failed<br>
>>>> after I applied power. I turned the volume up because I<br>
>>>> wasn?t hearing sferics, and shortly after, I heard the<br>
>>>> squeal of the DC-DC converter. When I pulled out the<br>
>>>> smaller foam core partially, I heard a squeal coming from<br>
>>>> the DC-DC converter itself.<br>
>>>> <image3.jpeg><br>
>>>><br>
>>>> I had a failure of the DC-DC converter when I first built<br>
>>>> the VLF preamp. It was being powered by the Raspberry Pi<br>
>>>> box (same power circuit as my text box). I had a power<br>
>>>> failure and when the power was restored, the DC-DC<br>
>>>> converter failed.? In both situations, it was being<br>
>>>> supplied with 30VDC, with the limit is 36V. The reason for<br>
>>>> using 30V is to overcome the voltage drop from long cable<br>
>>>> lengths.<br>
>>>><br>
>>>> After both failures, there was a low impedance across the<br>
>>>> input of the DC-DC converter causing the supply to be<br>
>>>> pulled down. Because the input and output are isolated, I<br>
>>>> figured the fault had to have been caused by a voltage<br>
>>>> spike on the input due to power being turned on and off.<br>
>>>> The datasheet mentions that it can withstand 50V spikes at<br>
>>>> 100ms, but I can?t think of anything else that could cause<br>
>>>> the DC-DC to fail, especially that 30V is used to power it<br>
>>>> and any voltage spike would ride on top of that 30V. I<br>
>>>> contacted XP Power about the issue.<br>
>>>><br>
>>>> Here is the schematic of the power path. The blocks are the<br>
>>>> IP2415S DC-DC converter.<br>
>>>> <image1.jpeg><br>
>>>> I?m powering the DC-DC converter with 30V from another<br>
>>>> DC-DC converter in the test box and Raspberry Pi box<br>
>>>> (Raspberry Pi box not shown, but same circuit). Keep in<br>
>>>> mind, the length is still relatively short in my testing,<br>
>>>> so cable inductance isn?t the primary reason for the spike.<br>
>>>> Plus, at long lengths, the voltage would be much lower due<br>
>>>> to voltage drop across the length, and I think this was why<br>
>>>> Paul might not have seen this issue when he originally<br>
>>>> tried and built this design.<br>
>>>><br>
>>>> To mitigate this problem with the supply voltage at 30V, I<br>
>>>> decided to use a TVS diode across the input of the DC-DC<br>
>>>> converter. Here is the schematic: (my apologies for the TVS<br>
>>>> diode being backwards)<br>
>>>> <image2.jpeg><br>
>>>> I chose a unidirectional TVS so there is also protection if<br>
>>>> the voltage spikes have any negative components. I picked a<br>
>>>> TVS with a working voltage of 33V, a Littel Fuse P4KE39A.<br>
>>>> According to the datasheet, it looks like this would be<br>
>>>> adequate. TVS diodes have a PN junction that is more<br>
>>>> rugged, with a larger surface area for greater current<br>
>>>> density. One thing I overlooked with this type of circuit<br>
>>>> protection is that once the TVS conducts, current from the<br>
>>>> power supply will be shunted too, known as the follow<br>
>>>> current, and in some situations, this may cause issues<br>
>>>> requiring a fuse. In this case, since the spikes are<br>
>>>> probably short duration, and since the DC-DC converter in<br>
>>>> the text/Pi box has short circuit protection, this should<br>
>>>> not be an issue.<br>
>>>><br>
>>>> So the questions I have are: do you also think it could be<br>
>>>> voltage spikes that caused the failures, and if so, was my<br>
>>>> choice of TVS diode adequate. Also, one important question,<br>
>>>> if I connect the anode of the TVS diode to the receiver<br>
>>>> side ground, will I lose isolation? I know that during<br>
>>>> spike current conduction, I will. I?m sure I can still get<br>
>>>> adequate protection with the TVS diode anode connected to<br>
>>>> the negative of the isolated power loop too, but I just<br>
>>>> wanted to be sure.<br>
>>>><br>
>>>> Lastly, since the magnetometer board will undergo another<br>
>>>> revision, I feel it may be worth it to add some sort or<br>
>>>> adjustable regulator or use of an external power source<br>
>>>> (not connected to the 5V pin of the Pi header) because even<br>
>>>> with paralleling wires or pairs, some installations will<br>
>>>> require very long lengths (especially since<br>
>>>> interference-free locations are often far away from the<br>
>>>> shack) and the voltage may drop to where the LDO cant<br>
>>>> regulate. Using a higher voltage at the Pi end (like I do<br>
>>>> with the VLF preamp) may be required for some<br>
>>>> installations. I think this should be considered if it<br>
>>>> already wasn?t addressed.<br>
>>>><br>
>>>> Jonathan<br>
>>>> KC3EEY<br>
>>>><br>
>>>><br>
>>>><br>
>>>> On Jul 27, 2021, at 7:21 AM, Dr. Nathaniel A. Frissell<br>
>>>> Ph.D. <<a href="mailto:nathaniel.frissell@scranton.edu" target="_blank">nathaniel.frissell@scranton.edu</a><br>
>>>> <mailto:<a href="mailto:nathaniel.frissell@scranton.edu" target="_blank">nathaniel.frissell@scranton.edu</a>>> wrote:<br>
>>>><br>
>>>>><br>
>>>>><br>
>>>>><br>
>>>>><br>
>>>>><br>
>>>>><br>
>>>>><br>
>>>>><br>
>>>>><br>
>>>>><br>
>>>>><br>
>>>>><br>
>>>>><br>
>>>>><br>
>>>>><br>
>>>>><br>
>>>>> Thank you, Tom.<br>
>>>>><br>
>>>>><br>
>>>>><br>
>>>>><br>
>>>>><br>
>>>>> The recording will be available later today at<br>
>>>>><br>
>>>>> <a href="https://youtu.be/AammohuygMw" rel="noreferrer" target="_blank">https://youtu.be/AammohuygMw</a><br>
>>>>> <<a href="https://youtu.be/AammohuygMw" rel="noreferrer" target="_blank">https://youtu.be/AammohuygMw</a>> and <a href="http://hamsci.org/telecons" rel="noreferrer" target="_blank">hamsci.org/telecons</a><br>
>>>>> <<a href="http://hamsci.org/telecons" rel="noreferrer" target="_blank">http://hamsci.org/telecons</a>>.<br>
>>>>><br>
>>>>><br>
>>>>><br>
>>>>><br>
>>>>><br>
>>>>> 73 de Nathaniel W2NAF<br>
>>>>><br>
>>>>><br>
>>>>><br>
>>>>><br>
>>>>><br>
>>>>><br>
>>>>><br>
>>>>> *From:* TangerineSDR <<a href="mailto:tangerinesdr-bounces@lists.tapr.org" target="_blank">tangerinesdr-bounces@lists.tapr.org</a><br>
>>>>> <mailto:<a href="mailto:tangerinesdr-bounces@lists.tapr.org" target="_blank">tangerinesdr-bounces@lists.tapr.org</a>>><br>
>>>>><br>
>>>>> *On Behalf Of *Tom McDermott via TangerineSDR<br>
>>>>><br>
>>>>><br>
>>>>> *Sent:* Monday, July 26, 2021 10:02 PM<br>
>>>>><br>
>>>>><br>
>>>>> *To:* TAPR TangerineSDR Modular Software Defined Radio<br>
>>>>> <<a href="mailto:tangerinesdr@lists.tapr.org" target="_blank">tangerinesdr@lists.tapr.org</a><br>
>>>>> <mailto:<a href="mailto:tangerinesdr@lists.tapr.org" target="_blank">tangerinesdr@lists.tapr.org</a>>><br>
>>>>><br>
>>>>><br>
>>>>> *Cc:* Tom McDermott <<a href="mailto:tom.n5eg@gmail.com" target="_blank">tom.n5eg@gmail.com</a><br>
>>>>> <mailto:<a href="mailto:tom.n5eg@gmail.com" target="_blank">tom.n5eg@gmail.com</a>>><br>
>>>>><br>
>>>>><br>
>>>>> *Subject:* [TangerineSDR] Notes from PSWS / TangerineSDR<br>
>>>>> call of 07-26-2021<br>
>>>>><br>
>>>>><br>
>>>>><br>
>>>>><br>
>>>>><br>
>>>>><br>
>>>>><br>
>>>>><br>
>>>>><br>
>>>>><br>
>>>>><br>
>>>>><br>
>>>>><br>
>>>>><br>
>>>>><br>
>>>>><br>
>>>>><br>
>>>>><br>
>>>>><br>
>>>>> Notes from PSWS / TangerineSDR call of 07-26-2021<br>
>>>>><br>
>>>>><br>
>>>>><br>
>>>>><br>
>>>>><br>
>>>>><br>
>>>>><br>
>>>>><br>
>>>>><br>
>>>>><br>
>>>>><br>
>>>>><br>
>>>>><br>
>>>>> 1. Bill is using chart.js for magnetometer charting. He is<br>
>>>>> setting up a database using Django web and database<br>
>>>>> framework for Python.<br>
>>>>><br>
>>>>><br>
>>>>><br>
>>>>><br>
>>>>><br>
>>>>><br>
>>>>><br>
>>>>><br>
>>>>><br>
>>>>><br>
>>>>><br>
>>>>><br>
>>>>><br>
>>>>> 2. Scotty is looking at the Intel (Altera) Arria 10 GX<br>
>>>>> FPGA 10GX270 for the version 2 Data Engine (supporting<br>
>>>>> 10GE). These FPGAs appear to be more available than the<br>
>>>>> MAX10 FPGAs. The intention is to develop DE Ver 1 and DE<br>
>>>>> Ver 2 in parallel<br>
>>>>><br>
>>>>> while awaiting FPGA component availability. The 10 GX<br>
>>>>> development boards are pretty expensive.<br>
>>>>><br>
>>>>><br>
>>>>><br>
>>>>><br>
>>>>><br>
>>>>><br>
>>>>><br>
>>>>><br>
>>>>><br>
>>>>><br>
>>>>><br>
>>>>><br>
>>>>><br>
>>>>> -- Tom, N5EG<br>
>>>>><br>
>>>>><br>
>>>>><br>
>>>>><br>
>>>>><br>
>>>>><br>
>>>>><br>
>>>>><br>
>>>>><br>
>>>>><br>
>>>>><br>
>>>>><br>
>>>>><br>
>>>>><br>
>>>>><br>
>>>>><br>
>>>>><br>
>>>>><br>
>>>>><br>
>>>>><br>
>>>>><br>
>>>>><br>
>>>>><br>
>>>>><br>
>>>>><br>
>>>>><br>
>>>>><br>
>>>>><br>
>>>>><br>
>>>>><br>
>>>>><br>
>>>>><br>
>>>>><br>
>>>>><br>
>>>>><br>
>>>>><br>
>>>>><br>
>>>>><br>
>>>>><br>
>>>>> -- <br>
>>>>><br>
>>>>><br>
>>>>> Please follow the HamSCI Community Participation<br>
>>>>> Guidelines at<br>
>>>>> <a href="http://hamsci.org/hamsci-community-participation-guidelines" rel="noreferrer" target="_blank">http://hamsci.org/hamsci-community-participation-guidelines</a><br>
>>>>> <<a href="http://hamsci.org/hamsci-community-participation-guidelines" rel="noreferrer" target="_blank">http://hamsci.org/hamsci-community-participation-guidelines</a>>.<br>
>>>>><br>
>>>>><br>
>>>>> ---<br>
>>>>><br>
>>>>><br>
>>>>> You received this message because you are subscribed to<br>
>>>>> the Google Groups "HamSCI" group.<br>
>>>>><br>
>>>>><br>
>>>>> To unsubscribe from this group and stop receiving emails<br>
>>>>> from it, send an email to<br>
>>>>> <a href="mailto:hamsci%2Bunsubscribe@googlegroups.com" target="_blank">hamsci+unsubscribe@googlegroups.com</a><br>
>>>>> <mailto:<a href="mailto:hamsci%2Bunsubscribe@googlegroups.com" target="_blank">hamsci+unsubscribe@googlegroups.com</a>>.<br>
>>>>><br>
>>>>><br>
>>>>> To view this discussion on the web visit<br>
>>>>> <a href="https://groups.google.com/d/msgid/hamsci/SA0PR03MB5547CBF733EFEB4D829E659FF2E99%40SA0PR03MB5547.namprd03.prod.outlook.com" rel="noreferrer" target="_blank">https://groups.google.com/d/msgid/hamsci/SA0PR03MB5547CBF733EFEB4D829E659FF2E99%40SA0PR03MB5547.namprd03.prod.outlook.com</a><br>
>>>>> <<a href="https://groups.google.com/d/msgid/hamsci/SA0PR03MB5547CBF733EFEB4D829E659FF2E99%40SA0PR03MB5547.namprd03.prod.outlook.com?utm_medium=email&utm_source=footer" rel="noreferrer" target="_blank">https://groups.google.com/d/msgid/hamsci/SA0PR03MB5547CBF733EFEB4D829E659FF2E99%40SA0PR03MB5547.namprd03.prod.outlook.com?utm_medium=email&utm_source=footer</a>>.<br>
>>>>><br>
>>>>><br>
>>> -- <br>
>>> Please follow the HamSCI Community Participation Guidelines at <br>
>>> <a href="http://hamsci.org/hamsci-community-participation-guidelines" rel="noreferrer" target="_blank">http://hamsci.org/hamsci-community-participation-guidelines</a> <br>
>>> <<a href="http://hamsci.org/hamsci-community-participation-guidelines" rel="noreferrer" target="_blank">http://hamsci.org/hamsci-community-participation-guidelines</a>>.<br>
>>> ---<br>
>>> You received this message because you are subscribed to the Google <br>
>>> Groups "HamSCI" group.<br>
>>> To unsubscribe from this group and stop receiving emails from it, <br>
>>> send an email to <a href="mailto:hamsci%2Bunsubscribe@googlegroups.com" target="_blank">hamsci+unsubscribe@googlegroups.com</a> <br>
>>> <mailto:<a href="mailto:hamsci%2Bunsubscribe@googlegroups.com" target="_blank">hamsci+unsubscribe@googlegroups.com</a>>.<br>
>>> To view this discussion on the web visit <br>
>>> <a href="https://groups.google.com/d/msgid/hamsci/59FAEE9C-11F5-4CDF-B960-2E583E42E89C%40gmail.com" rel="noreferrer" target="_blank">https://groups.google.com/d/msgid/hamsci/59FAEE9C-11F5-4CDF-B960-2E583E42E89C%40gmail.com</a> <br>
>>> <<a href="https://groups.google.com/d/msgid/hamsci/59FAEE9C-11F5-4CDF-B960-2E583E42E89C%40gmail.com?utm_medium=email&utm_source=footer" rel="noreferrer" target="_blank">https://groups.google.com/d/msgid/hamsci/59FAEE9C-11F5-4CDF-B960-2E583E42E89C%40gmail.com?utm_medium=email&utm_source=footer</a>>.<br>
>><br>
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</td>
</tr>
</table><a href="#DAB4FAD8-2DD7-40BB-A1B8-4E2AA1F9FDF2" width="1" height="1"></a></div>