Date   

Re: The Light APRS Reciever

Erwin - PE3ES - F4VTQ
 

For wspr spots you would normally go to

wsprnet.org not to pskreporter which is more useful for all the other digital and other modes.

Erwin
PE3ES/F4VTQ


not find error - no transmitting

HB9FIH
 

GD,

QCX 2017 / 2 #2306

Inn QTH TA3 2019 suddently no transmit. Several looked and changed PA...

But its not the PA.

Today removed Q4 / Q6 (and supplied precision pins) and checked.

Pin 16 of AtMega  is always low.

ATMega broken ?  - Also Display is broken (tested on Arduino)

(Cannot here make a bootstrap on a fresh ATMega - missing C for the circuit)


--
---
73 de Erich

HB9FIH

HS0ZLS


Re: Clock Display - Contrast Issue?

Phill M1PUW
 

Alan,

What did I find?  That I'm a muppet, is what.  I wanted to have the display on a ribbon cable.  I'd only put the perishing thing back to front.  After swapping the plug back around the right way it works nicely now.
Now for the GPS board.....

73s
Phill


.  


Re: Clock Display - Contrast Issue?

Alan G4ZFQ
 

- assembly manual http://www.qrp-labs.com/ultimate3/u3trouble
Phill,

Yes, specifically http://www.qrp-labs.com/ultimate3/u3trouble#squares
It does not mention scope checks so I cannot comment.
After you've done those checks tell us what you find.

73 Alan G4ZFQ


Re: Clock Display - Contrast Issue?

Phill M1PUW
 

Alan,

Thanks for your reply.  I'm not too sure where you mean:
- The troubleshooting page u3trouble 
or this one?
- assembly manual http://www.qrp-labs.com/ultimate3/u3trouble
 
Either way, I can't see a specific reference to comms between the two.  As I can see pulses on D4-7 my assumption was that the link between them is satisfactory.

Phill


Re: favorite DVMs

danielu@upcnet.ro danielu@upcnet.ro
 

Dear colleagues, stay away from OLED display devices, especially the VC890 made by Voltcraft . I can recommend , although not at 80Euro UNI-T71D (E)  because it measures frequency up to 400Mhz.
Best regards
Daniel Ungureanu
YO8SAK


Re: Clock Display - Contrast Issue?

Alan G4ZFQ
 

but this is the range of "contrast" I've been able to get out of the display.
Phill,

Your description shows that there is no problem with the contrast control.
There is no data coming from the processor.
This is shown in the manual, look at the troubleshooting page.

73 Alan G4ZFQ


Re: Measure LPFs Re: [QRPLabs] Impedance measuring

Andrew Lenton
 

Hi Your Nano VNA is working nicely

 

 

73

 

Andrew


Clock Display - Contrast Issue?

Phill M1PUW
 

Morning,

First post, so apologies if I get this stuff wrong.  Anyway, I received the clock and GPS kits this weekend and started putting the clock kit together.  There's not too much there, so what could go wrong.......

On powering it up I get 2 rows (I'm using a 20x4) of flashing blocks.  Adjusting the 100k pot makes no difference whatsoever.  The left button stops the flashing and the blocks then are either static, or fade away, dependent on the position of the pot.  Subsequent changes of the pot makes no change to the contrast.

I've:
- measured around the track of the pot (i.e. not off the slider) and it sits at 49k, which seems odd.  I didn't fit the optional 220k.
- checked continuity with all the leads (to the LCD) and they're fine

I'm using 5V from a Farnell bench supply, so can foreclose any PSU issues (unless that's gone haywire!).  

The oscillator works: I can see the pins D4-7 pulsing.  I know the following pictures don't really say a great deal, but this is the range of "contrast" I've been able to get out of the display.

Can anyone offer any help/suggestions, please?

73s 
Phill
M1PUW



Re: favorite DVMs

jim
 

One thing to be aware of is the input impedance of the "cheaper" meters ...Harbor Fright is 1 Mohm per volt ...Fluke is 10 Mohm per volt ...if you're futzing with fets it WILL make a difference ..

Jim

On Monday, April 6, 2020, 2:09:58 AM UTC, Dave Edwards <kd2e@...> wrote:


I'd be just fine with one, but I have this sickness.   I must own 30 of them!!   Although I use to work for HP/Agilent, so...they gave me 4 or 5 of them!! Current bench is a Keithley, and I often use small handheld Fluke, or Agilent.

....Dave

On 4/5/20 11:45 AM, Jim - W7EZN via groups.io wrote:
What are your favorite DVM's in the $50 - $75 range.  I have a cheapo analog and am thinking about a decent upgrade.  Maybe with a component tester on board?
--
Jim, W7EZN    73!


Re: favorite DVMs

Dave Edwards
 

I'd be just fine with one, but I have this sickness.   I must own 30 of them!!   Although I use to work for HP/Agilent, so...they gave me 4 or 5 of them!! Current bench is a Keithley, and I often use small handheld Fluke, or Agilent.

....Dave

On 4/5/20 11:45 AM, Jim - W7EZN via groups.io wrote:
What are your favorite DVM's in the $50 - $75 range.  I have a cheapo analog and am thinking about a decent upgrade.  Maybe with a component tester on board?
--
Jim, W7EZN    73!


Re: favorite DVMs

Glen Leinweber
 

Jim,
At one time in the distant past, Fluke commissioned a dual-slope integrating DVM chip (40-pin DIP).

A very similar 40-pin version was released by Intersil: the ICL7106.
The ICL7106 was designed to drive LCD 7-segment display of type "1.999" pin-for-pin direct.
The ICL7107 was designed to drive LED 7-segment display. Since a lot more
current was required, it ran hotter, so that the built-in voltage reference was less reliable
than the internal reference of the ICL7106

The ICL7106 is ubiquitously used as the heart of very many "3+1/2 digit" DVMs.
I had the opportunity to investigate closely its operation. It is a work-of-art!
Its linearity and offset performance is very impressive.
Many DVMs that use the ICL7106 have poor accuracy that can be traced to the
front-end resistor divider which scale down input voltage to be compatible with the
chip's input voltage range. The tolerances of these front-end resistors limit the
meter's accuracy. The chip itself is very linear.

So you can calculate a "scaling factor" for each DVM DC voltmeter scale if you have
a known good voltage reference. Once a scale factor is found, you can used it
to correct any reading on that scale.
Its not a good idea to try this on AC scales, since AC-to-DC conversion circuits
external to the ICL7106 chip are notoriously non-linear.


Re: favorite DVMs

Steve in Okinawa
 

Gonna jump in here to say i hate the auto-off on my two bench DMMs because they ALWAYS turn off while I'm juggling two probes. I love the ubiquitous $15 UT33D which is rugged and lacks auto-off but has extremely low drain when off so Is always there when i need it. And with decent DAISO batteries for 100 yen if I forget to turn it off no big deal. JS6TMW 


Re: favorite DVMs

Bill Cromwell
 

Hi,

RUD is a new expression for me. I used to know a licensed journeyman industrial electrician who put his meter across 440 volts AC while it was set to read ohms. yes...RUD. He was gone for several months and was vision impaired with a lot of scars. Lucky to be alive..I think. Be careful with those meters.

73,

Bill KU8H

On 4/5/20 2:16 PM, Stanly Witherspoon wrote:
This topic comes up enough on the EEVblog forums that there is a sticky on the info. There are a lot of junk DMMs.  If you are just doing low voltage(<48 V)they should be OK, but be aware of accuracy, noise and RF susceptibility. The issues start showing up in how they fail at higher voltages, such as wall AC, especially if you have them in the wrong mode. Some of the cheaper ones have done a RUD  (aerospace term: Rapid Unscheduled Disassembly:-)
Stan W AI6NF
--
bark less - wag more


Re: favorite DVMs

Daniel Walter
 

Many years ago (~40) I wanted a DVM as an upgrade from my Lafayette VOM. So I bought as good a Fluke as I could afford. It was defective on arrival! So I returned it for a no-name Scope 638 with more functions than the Fluke for about 1/3 the price. I'm still using it. Okay, the capacitance no longer works, but everything else does and does it well! So name and price don't always mean everything.  
--
73, Dan  NM3A


Re: Measure LPFs Re: [QRPLabs] Impedance measuring

Henk PA3BLP
 

For those who would like a better resolution photo, please email me at groups.iog_hb@...

with kind regards

Henkhenk

On 06-04-2020 01:24, Henkhenk wrote:
Here some (true screenshots) from my little nanoVNA (35 some euro, Aliexpress) when checking the low pass filters I made. I probably did one turn too many in some cases but well: 0.5 or 1 or even 1.5dB does not really hurt me. So not enough bother to try to correct the number of turns in the coils (if that is the cause).

When doing a sweep from 1 to 40 MHz (output) the response (input from the other side of the filter) should be within 0-2dB up to the working frequency and somewhere after the working frequency the output should decrease a lot so that on 2xf and 3xf the output is much lower (30 dB is possible). See my photos of the measuring setup (not high tech, just with some connectors I had laying around). Connecting two female pins from for instance a Arduino set makes plugging them onto the filters pretty easy. I found two times a non-connected wire of one of the coils, despite measuring input versus output on Ohms to ensure a DC path (and none to earth).

Explanation: the blue line is the signal that is the output of the LPF: above the working frequency of each filter you see a strong decrease of the signal. One square is 10dB. So 30 to 40dB (left bottom is 40dB supression) at 2*f and 3*f. And remember: the filter #0 is always in the output line so in my case with the 10m filter fitted everything above 40MHz is extra attenuated.

With kind regards

Henk PA3BLP

 

 



On 06-04-2020 00:49, fred.g3srf@... wrote:
I'm not certain that a LPF has a resonant frequency, it is a cut off frequency designed to remove harmonics. What are you showing in your picture of the analyser? Is your LPF showing a resonance at that frequency?
To check the response of a filter, it is best to look at a graphic display, does the Autek Research unit give such a display?




Re: favorite DVMs

Jim - W7EZN
 

Thanks everyone for some really great suggestions.  I have a lot of food for thought!
--
Jim, W7EZN    73!


Measure LPFs Re: [QRPLabs] Impedance measuring

Henk PA3BLP
 

Here some (true screenshots) from my little nanoVNA (35 some euro, Aliexpress) when checking the low pass filters I made. I probably did one turn too many in some cases but well: 0.5 or 1 or even 1.5dB does not really hurt me. So not enough bother to try to correct the number of turns in the coils (if that is the cause).

When doing a sweep from 1 to 40 MHz (output) the response (input from the other side of the filter) should be within 0-2dB up to the working frequency and somewhere after the working frequency the output should decrease a lot so that on 2xf and 3xf the output is much lower (30 dB is possible). See my photos of the measuring setup (not high tech, just with some connectors I had laying around). Connecting two female pins from for instance a Arduino set makes plugging them onto the filters pretty easy. I found two times a non-connected wire of one of the coils, despite measuring input versus output on Ohms to ensure a DC path (and none to earth).

Explanation: the blue line is the signal that is the output of the LPF: above the working frequency of each filter you see a strong decrease of the signal. One square is 10dB. So 30 to 40dB (left bottom is 40dB supression) at 2*f and 3*f. And remember: the filter #0 is always in the output line so in my case with the 10m filter fitted everything above 40MHz is extra attenuated.

With kind regards

Henk PA3BLP

 

 



On 06-04-2020 00:49, fred.g3srf@... wrote:
I'm not certain that a LPF has a resonant frequency, it is a cut off frequency designed to remove harmonics. What are you showing in your picture of the analyser? Is your LPF showing a resonance at that frequency?
To check the response of a filter, it is best to look at a graphic display, does the Autek Research unit give such a display?



Re: Impedance measuring

K2DB Paul Mackanos
 

Thanks for the heads up, I was thinking it had to be set for a freq. 
73 Paul K2DB

On Sun, Apr 5, 2020 at 6:49 PM <fred.g3srf@...> wrote:
I'm not certain that a LPF has a resonant frequency, it is a cut off frequency designed to remove harmonics. What are you showing in your picture of the analyser? Is your LPF showing a resonance at that frequency?
To check the response of a filter, it is best to look at a graphic display, does the Autek Research unit give such a display?


Re: Impedance measuring

fred.g3srf@...
 

I'm not certain that a LPF has a resonant frequency, it is a cut off frequency designed to remove harmonics. What are you showing in your picture of the analyser? Is your LPF showing a resonance at that frequency?
To check the response of a filter, it is best to look at a graphic display, does the Autek Research unit give such a display?