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Re: SD CARD "FAIL TO WRITE"
Hello Larry...thanks for response...I may have found the answer in
"messages"...my card is 32Mb and many responses to this "fail to write" are resolved with a slower 16GB card, so I ordered some... in reply to your questions, 1. new card, never used, never put into my computer; 2. inserted in Nano with power off; 3. never put into my computer... Mike On Thu, Nov 24, 2022 at 3:30 PM Larry McElhiney via groups.io <lmcelhiney= [email protected]> wrote: Hi Michael, |
Re: suspected faulty vna
General advice, Ken G3YKI, identify who you are responding to correctly! Just for your information, I know this wasn't directed to me but there could be a great number of people called Paul who could be subscribed to this group and all will be scratching their heads at seeing your post hit their inbox!
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-----Original Message-----
From: [email protected] <[email protected]> On Behalf Of Ken G3YKI Sent: 25 November 2022 09:35 To: [email protected] Subject: Re: [nanovna-users] suspected faulty vna General advice, and please do not be offended, Paul. If you have a long story, divide it up into several shorter sentences. It will be easier to get your message across and you will find it helps you to consider the problem more clearly yourself. |
Re: SD CARD "FAIL TO WRITE"
If r93 is a 10 ohm resistor, try shorting r93.
/g/nanovna-users/topic/micro_sd_card_issue/94630098?p=,,,20,0,0,0::recentpostdate/sticky,,,20,2,20,94630098,previd%3D1668372635506758650,nextid%3D1666746808442404351&previd=1668372635506758650&nextid=1666746808442404351 |
Re: SD CARD "FAIL TO WRITE"
Hi Michael,
1) Have you previously written to that card or is it the first time. (I.e., compatibility) 2) Was the card in the slot when you powered up or did you insert it with power on? (Best to insert and remove with no power.) 3) When you read the card from your computer do you always reject the card electronically before removing it? Hope it gets resolved for you. Larry AC9OX |
Re: SD CARD "FAIL TO WRITE"
Most likely need to use a different card. Some are not compatible.
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Search the messages here for SD card to see what has been shared by others on this topic. On Thu, Nov 24, 2022, 12:19 PM Michael Reid <mhreid4@...> wrote:
New NanoVNA-H4 with latest DiSlord v.1.2.00 upgrade, Clk SD CARD, Clk Save |
Re: suspected faulty vna
On Thu, Nov 24, 2022 at 07:25 PM, Jim Lux wrote:
Jim, Ok, my bad, my answer was too short, I should have written: Don't be surprised if you measure 50 ¦¸ - and if you do not see 50 ¦¸ think twice what could be the reason. You gave good examples of influence: On Thu, Nov 24, 2022 at 07:25 PM, Jim Lux wrote: only if the power is onOn Thu, Nov 24, 2022 at 07:25 PM, Jim Lux wrote: be careful measuring the ports of RF devices with a ohmmeterYou could measure the port resistance of the VNA with a VNA - oops, catch 22 :) Martin |
Re: suspected faulty vna
On 11/24/22 9:29 AM, Ho-Ro wrote:
On Thu, Nov 24, 2022 at 05:47 PM, Paul M3VUV wrote:measured the resistance on the s11 port on my vna ... it read 49 ohms ... is that normal ... ? On a NanoVNA the CHO port connects to a bridge with ~50 ohm DC resistance. See the schematic of at least one version. CH1 connects to a attenuator, also with approximately 50 ohm DC resistance. All RF devices have input and output resistance of 50 ¦¸ - unless you're in the TV business (they have 75 ¦¸) - otherwise youi'll get reflections (bad SWR).That's not generally true - A lot of devices will have a RF impedance of 50 ohm resistive, but that's also only if the power is on and if the other ports are terminated in their expected impedances. And at the design frequency. For example, a Bias T might show infinite DC resistance, because there's a blocking capacitor. a typical power divider will NOT show 50 ohms DC resistance, depending on the configuration. A Wilkinson, certainly not, since it depends on the impedance transformation of the 1/4 wavelength lines. Same with a Lange coupler. A "triangle" resistive power divider might show 50 ohms DC, if the output ports are terminated in 50 ohms. One does want to be careful measuring the ports of RF devices with a ohmmeter, too. For instance the NanoVNA2 has some RF switches connected directly to the ports, and depending on the voltage of your ohmmeter, those could be damaged. |
Re: suspected faulty vna
On Thu, Nov 24, 2022 at 05:47 PM, Paul M3VUV wrote:
measured the resistance on the s11 port on my vna ... it read 49 ohms ... is that normal ... ?All RF devices have input and output resistance of 50 ¦¸ - unless you're in the TV business (they have 75 ¦¸) - otherwise youi'll get reflections (bad SWR). Martin |
Re: max save slots on the vna "h" version running hugens fw
On Thu, Nov 24, 2022 at 04:45 PM, Paul M3VUV wrote:
Paul, Trace 1? Yellow is the color of the 1st trace (Trace 0) - but nevertheless: Menu - Display - Trace - set Trace 0 active - Back - Format S11 (Refl) - set SWR active Enable/disable the other traces accordingly. Martin |
suspected faulty vna
Hi all,long story my homebrew pi network atu wasnt tuning so stuck my v2 vna on it to have a look,at one point in the c2(variable cap nearest the output jack for the rig)looked as iff the vanes were shorting to ground,after removing the said cap it actualy looked ok but both sides looked like shorting to ground,the cap was still wired to the atu at this point, also the vna was conected to the atu,my meter was belling out between both legs of the cap and ground,i disconnected the vna and it stopped buzzing,i then measured the resistance on the s11 port on my vna,ie the center pin and outer of the s11 plug,it read 49 ohms low enough to make my fluke 87 dmm buzz on resistance mode,is that normal or a diode sc in my vna front end?.
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Re: Nano vna-saver
On 11/24/22 5:57 AM, N3MEL - Glenn wrote:
Is there a document that better explains what the returned data from a sweep really means?In terms of the raw message from the NanoVNA (in response to the "data" command)? It's real and imaginary of the reflection coefficient(for CH0) or transmission coefficient (for CH1) You'll also need to do a "sweep" command which returns the start and stop frequency, and number of points. The document I use is a pdf from 2019 called NanoVNA_Console_Commands_Dec 9-19.pdf It's on the wiki here /g/nanovna-users/wiki#For-Beginners-and-Experienced-Users 73 de Glenn N3MEL |
Re: Problem with eBay seller SV4401A: CAUTION11
#buying
I would also encourage you to try PayPal, and to include any independent statements you can get about the non-delivery of your item.
I raised a case with eBay about non-delivery of an item from a UK seller which may, in fact, have never been sent. eBay were unhelpful and did the same thing to me as they did to you: removed the item from my "purchased" list as soon as the case was opened. Fortunately I had email copies of all the invoices, shipping advice, etc. I submitted these to PayPal, and received a commitment to resolve the case one way or the other within a couple of weeks. Within an hour or two of submitting the case to PayPal, eBay closed the case - despite their tardiness in getting an actual human to discuss my case (never did achieve that). A few days later PayPal refunded my money, including shipping, taxes and foreign exchange charges. Although the amount involved was not huge, I considered the PayPal purchasing charges to be well worthwhile. Don't waste your time with eBay, but do see if you can get some independent statement about the fictitious package for PayPal. And, as others have said, stay with the more reputable sellers - I only buy from "RF" oriented sellers (check out their "other items") with manufacturers' recommendations. Regards, Peter. |
Re: Problem with eBay seller SV4401A: CAUTION11
#buying
I'm careful, but my experience with PayPal fixing bad deals, frauds,
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non-deliveries, etc, is very good and has been for years. I never leave money with them. Chuck On Wed, Nov 23, 2022 at 8:58 PM Mike C. <mg@...> wrote:
I agree, Paypal is UNSCRUPULOUS, disagree?? Read the story about the guy --
Chuck Cole ?K4TZO |
Re: Problem with eBay seller SV4401A: CAUTION11
#buying
I've been lucky that I have not actually lost any money. I've always managed to get a refund. My close calls have all been on deals that seemed too good to be true. One was half the price of any other vendor with "free delivery" by FedEx!
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Lesson (re)learned. If its too good to be true it probably isn't real, especially on the Internet. On Wed, Nov 23, 2022 at 02:37 PM, Costin R wrote:
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Re: Problem with eBay seller SV4401A: CAUTION11
#buying
Of course anyone¡¯s experience may vary, but over a period of years I have made purchased dozens of purchases from both AliExpress and Banggood. I have never had any issues with either group.
However my guiding credo is: If a price is too good to be true, it probably is. (I never buy from commercial vendors selling on eBay.) Over the many years of having a PayPal account, I have never had to file a dispute with them. Maybe I have been lucky¡ |
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