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Re: Voltage sensing diode
On Thu, Oct 31, 2019 at 11:31 AM, Raymond Domp Frank wrote:
OK I just checked my OTHER unit. I got it weeks after the first one and from a different supplier. Same diode installed - no problems with the unit whatsoever calibrates and works great. With unit OFF (USB NOT plugged in) Actual V at battery terminals = 4.17 V Actual voltage at cathode of diode = 4.13V About the same Vdrop across the diode with power unplugged, checked with the Rigol in diode check mode. So, there you have it. I'm going to take a break Raymond because I have other things to do. I thank you for working along but I do not think you are correct in your analysis (neither am I) . I think others may want to try and play along or explain what the observations are. I will check in later and see if I can add any more to it. But again I do not think we understand this circuit in toto. I've learned in life if the facts don't fit your understanding, then you may need to change your understanding. Talk to you guys later today. |
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Re: Voltage sensing diode
On Thu, Oct 31, 2019 at 07:29 PM, Mike_nano wrote:
You're right, I didn't see that. With the NanoVNA off, there shouldn't be a voltage supplying the IC, resulting in 4V on the Vbat terminal. Looks like a problem (defect?) in the IC or circuit. Maybe there's a short (solder bridge?) in your PCB. This means that you'll have a battery symbol and voltage indication even without D2, correct? Raymond |
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Re: Voltage sensing diode
Rich,
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Vdd is NOT what the 5303 is putting out - that is 5V Vdd? IS? the output of the LDO XC6206P332MR? 3V regulator. Check the attached schematic. On Thursday, October 31, 2019, 2:19:43 p.m. GMT-4, Rich NE1EE <ne1ee@...> wrote:
Hi Mike I get where you are coming from...but it's the drop /across/ the diode that is important. It's not what the batt has, or what VDD is, it is what VBAT sees. The USB and the batt both feed the 5303, and IT feeds the ST. So VDD is whatever the 5303 is putting out. VBAT is a different story. In the device, the batt feeds BOTH the 5303 (at say 4.1V) and the diode. So it sounds like you are measuring the anode. Measure across the diode, and tell us what you see, with USB power and/or no USB power. 73 ~R~ On 2019-10-31 11:07:-0700, you wrote: On Thu, Oct 31, 2019 at 10:28 AM, Raymond Domp Frank wrote:It is NOT achieved though ... that's my point - it doesn't do that. It isn't preventing the 4V Max rating from being reached with the other components in the unit such as the actual battery supplied. I just measured mine again. This with the SD103AWS part for the diode. -- On the banks of the Piscataqua Rich NE1EE |
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Re: Voltage sensing diode
On Thu, Oct 31, 2019 at 07:21 PM, Mike_nano wrote:
Not re. what the voltages or the circuit *should* be. That should never happen; it's a problem in your IC or circuit. Vbat should *never* source a current. Raymond |
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Re: IP3 measurement
Under very carefully controlled circumstances you can use the nanoVNA as a poor mans spectrum analyzer
/g/nanovna-users/topic/34079496#3464 Or better said, as a tunable power meter as there are many things you have to be careful about. First: make sure input power to CH1 is ALWAYS below -10dB to avoid artifacts Second: make sure there are no other signals, only the fundamental and its harmonics. Or for a two tone IIP3 the two tones plus their harmonics Example measurement: Set the transmitter on a fixed frequency into a dummy load, tap of a tiny bit of signal (below -10dB) into the nanoVNA CH1 and set the sweep very narrow (100Hz steps max) to where the fundamental(s) and the harmonics should be. Read the power from the CH1 logmag graph. Add a 10dB attenuator and repeat the whole measurement. This should give the SAME numbers, only 10dB lower. If not you are overloading the CH1 input and the nanoVNA is generating the harmonics.Or there are unwanted mixing product making the measurement impossible |
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Re: Voltage sensing diode
On Thu, Oct 31, 2019 at 07:21 PM, Mike_nano wrote:
I don't deny any measured facts. I know what the circuit is - or is supposed to be. I *don't* know what your NanoVNA behaves like, apart from what you describe. Either the diode is leaky (which to me seemed/seems more likely) or what's "behind" your Vbat terminal is problematic/leaky. What do you measure with the NanoVNA off, i.e. no Vdd present? Raymond |
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Re: Using a larger battery
Hi Barry,
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You will have no issues using that battery as long as you keep the original protection PCB (the small board inside the battery). Look at some of my posts - I use a cellphone battery as-is.? /g/nanovna-users/message/5913 On Thursday, October 31, 2019, 1:47:39 p.m. GMT-4, BARRY JACKSON via Groups.Io <g4mkt@...> wrote:
Hi folks, I just happen to have a spare 3.7v 2Ah battery from a new Baofeng 888 hand-held which has been stripped down for use in an Allstar micronode. I can't think of a reason why this should not be used to replace the 500mAh battery in the NanoVNA. I appreciate that the charge time would increase but this is not an issue for me. My plan would be to use longer spacers and attach the battery inside the bottom cover rather than the main PCB. I would appreciate any thoughts from the group. Barry. |
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Re: Voltage sensing diode
On Thu, Oct 31, 2019 at 11:14 AM, Raymond Domp Frank wrote:
Nope ... just checked it with the battery pulled - it has 0.243 V drop. So do the other diodes I purchased that are unused. No, there is a misunderstanding of the voltages in the IC or the circuit that is obvious now. Don't be so certain you know what is going on. I certainly do not at the present time. Something on the cathode side of the diode in the IC has more than 4.0 volts and it shows at the Vbat pin. You cannot deny the measured facts. FYI using a Rigol DM3058E |
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Re: Voltage sensing diode
Hi Mike
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I get where you are coming from...but it's the drop /across/ the diode that is important. It's not what the batt has, or what VDD is, it is what VBAT sees. The USB and the batt both feed the 5303, and IT feeds the ST. So VDD is whatever the 5303 is putting out. VBAT is a different story. In the device, the batt feeds BOTH the 5303 (at say 4.1V) and the diode. So it sounds like you are measuring the anode. Measure across the diode, and tell us what you see, with USB power and/or no USB power. 73 ~R~ On 2019-10-31 11:07:-0700, you wrote:
On Thu, Oct 31, 2019 at 10:28 AM, Raymond Domp Frank wrote:It is NOT achieved though ... that's my point - it doesn't do that. It isn't preventing the 4V Max rating from being reached with the other components in the unit such as the actual battery supplied. I just measured mine again. This with the SD103AWS part for the diode. --
On the banks of the Piscataqua Rich NE1EE |
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Re: Voltage sensing diode
On Thu, Oct 31, 2019 at 07:07 PM, Mike_nano wrote:
My Schottky diode wasn't one of those. Schottky diodes tend to (forward) leak a bit more than regular good PN Si diodes. I replaced the Schottky with a regular PN Si diode and now my voltage indication (without offset adjustment) is much better. Raymond |
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Re: Voltage sensing diode
On Thu, Oct 31, 2019 at 07:07 PM, Mike_nano wrote:
No misunderstanding of functionality. Your diode is leaky I guess. I'm not sure about the current (through the diode) into the Vbat connection (going to measure that one of these days) but in my case, the difference between a Schottky and a regular Si PN diode was over 300 mV so there definitely *is* some current flowing. Raymond |
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Re: Using a larger battery
David KD4E
I don't know this but I was once warned about attaching a large
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external battery to a UPS box - you might overheat the charging circuit on the board - because it was only designed to maintain a smaller battery. It may be nothing ... David KD4E Hi folks, I just happen to have a spare 3.7v 2Ah battery from a new Baofeng 888 hand-held which has been stripped down for use in an Allstar micronode. |
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Re: Voltage sensing diode
On Thu, Oct 31, 2019 at 10:28 AM, Raymond Domp Frank wrote:
It is NOT achieved though ... that's my point - it doesn't do that. It isn't preventing the 4V Max rating from being reached with the other components in the unit such as the actual battery supplied. I just measured mine again. This with the SD103AWS part for the diode. With unit OFF (USB NOT plugged in) Actual V at battery terminals = 4.13 V Actual voltage at cathode of diode = 4.14V With unit ON (USB NOT plugged in) Actual V at battery terminals = 4.13 V Actual voltage at cathode of diode = 4.11 V These are the actual voltages I checked them several times. I do not see a 0.2 V drop across the diode. I think we are misunderstanding some functionality ... |
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Re: Measuring swr
On Thu, Oct 31, 2019 at 10:11 AM, Larry Rothman wrote:
--------------------------------------------------------------------------------------------------------- You'd be surprised how many under warrenty Tracfone smartphones are still at version 4.4 :) My biggest fear would be losing data stored in my phone during the rooting and upgrade process. - Herb |
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Using a larger battery
Hi folks, I just happen to have a spare 3.7v 2Ah battery from a new Baofeng 888 hand-held which has been stripped down for use in an Allstar micronode.
I can't think of a reason why this should not be used to replace the 500mAh battery in the NanoVNA. I appreciate that the charge time would increase but this is not an issue for me. My plan would be to use longer spacers and attach the battery inside the bottom cover rather than the main PCB. I would appreciate any thoughts from the group. Barry. |
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Re: Voltage sensing diode
On Thu, Oct 31, 2019 at 06:06 PM, Mike_nano wrote:
It's not an error. The diode is just there to prevent Vbat from ever exceeding the IC's absolute maximum rating of 4V. With either a Schottky or traditional Si diode, that is achieved, because the diode drops at least 0.2V (Schottky) and 0.5V (PN Si), usually more. Since the actual Vbat is dependent on diode type (technology) and sample, voltage indication has to be tuned for each NanoVNA for optimum results. QRP RX's recent offset adjustment facility (I haven't tried it yet) allows just that. Because of a.o. the temperature dependence of the voltage across the diode (about -2mV/K .. -2.5mV/K), displaying more than 2 decimals (10 mV resolution) doesn't make sense, unless you want to make a thermometer. I'm going to do some measurements one of these days and also check if just taking an offset is good enough. and publish here. Raymond |
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Re: Newbie
Yup - about 600mAH?
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I raised the rear cover using an extra 2mm using a small hex nut under each (longer) screw and it works great. I'll have to see how long it runs on one charge. The only issue I have now is I cannot perform a screen capture as my device has a clone ILI9343 display - INANBO-T28SPIP18-V16? It appears this display's RAM buffer cannot be read. On Thursday, October 31, 2019, 12:21:00 p.m. GMT-4, Dick <w1ksz@...> wrote:
That looks like the Battery from an old Motorola RAZR Cell-Phone. They are still available on e-Pay for short money. 73, Dick, W1KSZ ________________________________ From: [email protected] <[email protected]> on behalf of Larry Rothman <nlroth@...> Sent: Monday, October 21, 2019 4:59 AM To: [email protected] <[email protected]> Subject: Re: [nanovna-users] Newbie You could do what I did when I got my Nano back in June - use a very thin cellphone battery.It's perfectly safe and there are a couple of photos in the photo section of the forum: /g/nanovna-users/photo/0/40?p=Created,,,20,1,40,0 ? ? On Monday, October 21, 2019, 7:47:07 a.m. GMT-4, hamrad45 <hamrad@...> wrote: Excellent information.? Thanks for taking the time to provide this information. Tom Stiles | | |? | Welcome to Groups.io! | | | |
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Re: Voltage sensing diode
On Thu, Oct 31, 2019 at 05:04 PM, QRP RX wrote:
I have all instruments and tools to exactly measure the voltage behavior of my NanoVNA. I'll try and find the time one of these days. Raymond |
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Re: Measuring swr
I don't think users running android 6 or less have to worry about warranty at this point.
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On Thursday, October 31, 2019, 12:46:59 p.m. GMT-4, hwalker <herbwalker2476@...> wrote:
In my experience if an app is not downloadable from Google Play Store because it does not support your phone version, then you will not be able to side load it either.? At install you generally receive a message that effectively? means the app is not compatible with your phone version.? Pretty much the only way around it is to root your phone and install a 7.0 or higher rom from XDA or one of the other sites that offer un-official upgrades.? The procedure voids your phone warranty and is not for the faint of heart. - Herb |
Rich NE1EE
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