Date   

Re: 10W PA and HackRF #pa

Karsten Benz
 

Thanks, this probably explains it.

And it's the information I was looking for. Couldn't find it in the instructions ... My apologies if I overlooked it.

Allegedly the HackRF puts out 5dbm to 15dbm in the range 0-10MHz, increasing with the frequency.

That should work in the higher ranges.

But I will have to investigate my transmission line as well ...

Cheers, 

-Karsten-
--
Karsten Benz - ZL1KPB


Re: Does QCX Mini have DIY emission indication function? #qcxmini

John Pagett G4YTJ
 

Alan,

You are right, that there can’t be a single ended indicator. But what the circuit diagram shows and what is reality can differ. Let’s assume there’s some capacitance to ground at the LED. To charge this capacitance, current would flow through one diode (with a smaller amount through the junction capacitance of the other diode). To discharge the stray capacitance, the current will then pass through the other diode, passing through the LED on the way.

I’m not saying that this is what happens, just that it’s a possible explanation.

Tomorrow afternoon happens to be a “do some electronics / radio” session over Zoom with a couple of friends. I’ll lash something up and see what results I get.

Pagett’s axiom - When reality and theory differ, reality takes precedence.

73
John Pagett
G4YTJ

On 17 Mar 2021, at 17:19, Alan G4ZFQ <alan4alan@...> wrote:



So chucking a "single ended" indicator to it is quite safe, it when you make it a "double ender" that it becomes a problem.
There can be no "single ended" indicator. If it indicates it is consuming power that has to be returned, just like an antenna.

I would think that any harmonics would be low but they could well be there.

73 Alan G4ZFQ






Re: Battery Indicator Showing Zero Bars

GIUSEPPE
 


Il mer 17 mar 2021, 18:13 Steven J. Hlibichuk <sjhlibichuk@...> ha scritto:
I will send the info in English once I'm back in front of my computer this evening. 

On Wed, Mar 17, 2021, 11:11 AM ae1ct1998 <AE1CT1998@...> wrote:
Went to his site but I couldn't read anything it was in a differant language


Re: Does QCX Mini have DIY emission indication function? #qcxmini

geoff M0ORE
 

Agreed 100%.

A diode across the RF was used and maybe still is to generate harmonics. Called Varactor diodes when I used one is a Wood & Douglas 70cm rig.

On 17/03/2021 17:18, Alan G4ZFQ wrote:

So chucking a "single ended" indicator to it is quite safe, it when you make it a "double ender" that it becomes a problem.

There can be no "single ended" indicator. If it indicates it is consuming power that has to be returned, just like an antenna.

I would think that any harmonics would be low but they could well be there.

73 Alan G4ZFQ







Re: Does QCX Mini have DIY emission indication function? #qcxmini

Arv Evans <arvid.evans@...>
 

There are several types of SWR bridge that can be left in-circuit full-time. 
These draw little current through the FWD and REV bridge and can to
set up to drive either LEDs or meter(s).  If there is room enough, one of
these can be installed inside or just outside the chassis for indicating RF
presence. 

Hmmmm...maybe put an SWR bridge in the ground circuit as well to see
just how good your ground might be.   😁

Arv  K7HKL
_._


On Wed, Mar 17, 2021 at 9:34 AM <jakob@...> wrote:
Is that a prank or can you explain this circuit's method of operation?


Re: Can't enter setup mode. #40m

Drsammoore <Drsammoore@...>
 

I had seen another report of the 5V not feeding this area of the board (bad conn or feed-thru).  I had jumpered the 5V, but had the 5V jumpered in to the wrong side of R24/25.  After moving, the QCX 40 went into the setup mode just fine.

In the setup mode, I had no tone thru the headphones.  Also saw a post about this, where the guy didn't have C21/22 in his.  I had C22 in the C54 spot (C54 not used on this version). All worked fine after moving C22. 

I made a contact 2 states away on 40 with a 579 RST!

It's all good!

73, Sam, W5GND  


-----Original Message-----
From: Ham Radio <bernard.murphy@...>
To: QRPLabs@groups.io
Sent: Wed, Mar 17, 2021 12:44 pm
Subject: Re: [QRPLabs] Can't enter setup mode. #40m

What is your result as outlined in Mel’s response?
You should see three different voltages as you push each left and right button and the encoder push button.  Measure as close to pin 26 to the micro as you can.
--
73, Bernie, VE3FWF
(most typos in this message have been generated by highly sophisticated auto-correction software)


Re: Can't enter setup mode. #40m

 

What is your result as outlined in Mel’s response?

You should see three different voltages as you push each left and right button and the encoder push button.  Measure as close to pin 26 to the micro as you can.
--
73, Bernie, VE3FWF
(most typos in this message have been generated by highly sophisticated auto-correction software)


Re: QCX+ station

Al Holt
 

Nice looking set up!

I'd like to chime in on the ATU-100 tuner. I have 2, one purchased completely assembled and the other a kit with SMD parts pre-installed. 
I opened the case on the completely assembled unit and found a couple of things I didn't like. First the 'tradem match' transformer was wound with 11 turns, not the normal 10. But the firmware 3.2 firmware had the turns 'cell' set for 10. Second, the toroids are all wound with 1 additional turn than what's spec'ed on the schematic.  Again, the firmware did not account for the change in inductance with the added turn.

I've been using it with a 100 foot 'all-band' doublet fed with ladder line through a 4:1 balun. My rig is an Icom 718. The pre-built ATU-100 has been struggling to get a match on 80m an can't seem to get it below 2:1. There's some question in this board's case if proper BAT41 diodes have been used. Right now I'm trying a couple of vintage 1N34A's as replacements, but performance is still 'iffy.'

The kit unit seems to be working better. I have the 'tandem match' set with 6 turns (to handle ~55W) which is supposed to give better low-power performance. But, it also has that tuning problem on 80m, if I recall correctly. I plan to mount it in a QCX+ like case and use a 16x2 display.

There's more tweaking I want to do with these two tuners, but I feel like they are better suited to use with my QRP Labs equipment.

I've joined the groups.io that supports the ATU-100 but there haven't been any posts since Feb. 20. I tried contacting the admin without receiving a response. I think, posts to that group have to be approved by the admin prior to showing up on the list.

Please, I don't want to derail this tread as the ATU-100 is way off topic relative to this list. Any follow up should be off-list Thanks!!

--Al
WD4AH


Re: Does QCX Mini have DIY emission indication function? #qcxmini

Alan G4ZFQ
 

So chucking a "single ended" indicator to it is quite safe, it when you make it a "double ender" that it becomes a problem.
There can be no "single ended" indicator. If it indicates it is consuming power that has to be returned, just like an antenna.

I would think that any harmonics would be low but they could well be there.

73 Alan G4ZFQ


Re: Battery Indicator Showing Zero Bars

Steven J. Hlibichuk
 

I will send the info in English once I'm back in front of my computer this evening. 


On Wed, Mar 17, 2021, 11:11 AM ae1ct1998 <AE1CT1998@...> wrote:
Went to his site but I couldn't read anything it was in a differant language


Re: 10W PA and HackRF #pa

ajparent1/kb1gmx
 

 50 millivolts of rf is not the needed 25 milliwatts of rf.
Actually its not even 1 milliwatt more like maybe 100 microwatts.

It may generate a few milliwatts of RF out oif working normally

No Data on HackRF power out if any.


Allison
-------------------------------
Please reply on list so we can share.
No private email, it goes to a bit bucket due address harvesting


Re: Battery Indicator Showing Zero Bars

ae1ct1998 <AE1CT1998@...>
 

Went to his site but I couldn't read anything it was in a differant language


Re: Does QCX Mini have DIY emission indication function? #qcxmini

David
 

Is that a prank.  Ha Ha, well it isn't  April 1st yet.  No it isn't a prank and no I can't explain how it works.  It seems too simple.
Anyway I have moved the "circuit" from the BNC to the junction of C27, C29 and L3.  That way if there are any harmonics generated,  hopefully,  they will be attenuated when they pass through the LPF.  The photo shows my 20M QCX which is fitted to a copper clad paxolin board which is useful for carrying out experiments such as AGC etc. The QCX was putting out about 3.5 watts into a dummy load. The LED was brighter than it looks but didn't show up too well.   The original idea behind this circuit was to use it to test for the presence of rf and the components could be mounted inside a biro pen. Again, thanks to Andy/G0FTD for his idea in using it as a piece of test equipment. 73 Dave M3PMG






Re: Can't enter setup mode. #40m

Drsammoore <Drsammoore@...>
 

I found I had the jumper to the 5V line on the wrong side of the resistor! After this I could enter the setup mode.

I then had no tone when I got to that step in setup, but found I had put C22 in C54 spot (which isn't even used). {I used another fellow's post on here with that problem & he had forgotten c21/c22.  Mine was almost identical! }

 I aligned the QCX 40  & double checked & resoldered a bunch of connections & now it seems to work great!  I just made a 40M contact 2 states away & got a 579!

Thank goodness for this website!  

Another QCX 40 on the air. Thanks everyone for the troubleshooting ideas!

73, Sam, W5GND


Re: A simple QCX AGC #mods #qcx

Jack G5JDA
 

Looks like a good mod. I'd be happy to design an SMD PCB for the job, unfortunately haven't gotten around to assembling my mini so will need assistance with permissible dimensions. What cost for an assembled unit do people think is tolerable?


Re: Does QCX Mini have DIY emission indication function? #qcxmini

Albert Tatlock's Greatest Hits - Vol 1
 

Diodes and harmonics.

HInt, solder one end of a diode to the output and observe the effects.

What, you mean there aren't any ? ;-)

Now solder the other end across the output (like some QCX user tried to).

Oh look, harmonics.

So chucking a "single ended" indicator to it is quite safe, it when you make it a "double ender" that it becomes a problem.

Incidentally the "diode double ender" can be made into a useful trick for old signal generators that lack VHF / UHF
coverage.

I keep a diode strapped across a connector, that in turn can be attached or un-attached to a t-piece on the output
of a 0 - 150Mhz sig genny in order to extend it's range up to UHF.


Re: QCX+ R48 gets very hot #qcx

Bob Groh wa2cky
 

Adding this discussion to my list of things to do in QCX+ (some day soon!!).  But a comment: why not wiggle another 5V regulator in the box?  The QCX+ has some spare room (and, yes, I did buy the accessory board just in case).  For example, my build is going to use a 3.3V regulator to drive the Si chip instead of the 2 diode scheme.  

73
Bob Groh, WA2CKY

On Tue, Mar 16, 2021 at 10:21 AM Mont Pierce KM6WT <de.km6wt@...> wrote:
On Mon, Mar 15, 2021 at 05:48 AM, Mehmet Dinch wrote:
Anyone notice that R48 (270 ohm) gets very hot?
R48 is the resistor on the right located on the front panel, just above the LCD module.
Looking at the circuit, it looks like a current limiting resistor for the LCD 12v suplpy line.
Yes, I was quite surprised the first time I touched it.

Here's a dumb question...   ( Hans, see the P.S. below.  :) 

Why is the 12V line used to drive the LCD backlight on the QCXs?  
On the QL kits with the QCU PCB, the LCD is driven with 5V.  (Of course, only 5V available on these).

Hmmmm... reviewing the QCX+ assembly manual (click here), top of page 116 explains:

The LCD backlight consumes about 30 or 35mA of current. The backlight could be connected directly to the 5V supply but this would somewhat increase the power dissipation of the 7805 regulator. In order to avoid overheating the regulator, this backlight is powered instead directly from the +12V rail via R48, a 270-ohm resistor. This resistor value was chosen so that over a supply voltage range of 7 to 20V the backlight brightness still appears reasonable. If you want a reduced brightness display, you could increase the value of R48.

Similar comment in the QCX-mini assembly manual (click here), page 98 2nd paragraph: 

The back-light could be
connected directly to the 5V
supply but this would somewhat increase the power dissipation of the 5V voltage regulator.
In order to avoid overheating the regulator, this back-light is powered instead directly from
the +12V rail via R48, a 560-ohm resistor.


Two points of interests to me in these quote:
  1. the mini uses 560 ohms instead of 270 ohms for R48. 
  2. in the mini R48 is only slightly warm, but NOT Hot like the QCX+'s 270 ohm resistor.

I think I'm going replace the R48s in my QCX+s to 560 ohms, or maybe a 1K pot in series with the 270 ohm.  :)  :)


73
km6wt

P.S.   Hey Hans, I think I'm finally learning  :)  :)      EVERYTHING we need/want to know, can ALWAYS be found in one of your manuals.   THANK YOU !!


Re: A simple QCX AGC #mods #qcx

Gregg Myers
 

Hi Jim,

Do you think 8mm x 23mm would fit in a mini? I figured out how to put components on both sides of the board and now have this:


73,
Gregg W7GRM

On Wed, Mar 17, 2021 at 7:17 AM Jim AJ8S <aj8s@...> wrote:
David,

Nice job with the perfboard, a lot better than my "flying mid-air" solder job! I agree with Dean... ...if someone wants to offer a PCB, either thru-hole or SMD, that would be great! Long and narrow so it also fits in the mini would be best.

Jim AJ8S


Re: Does QCX Mini have DIY emission indication function? #qcxmini

jakob@...
 

Is that a prank or can you explain this circuit's method of operation?


Re: Transmitting at power on

Robb Cole N2VJO
 

I had a similar issue - check to see if your unit beacon mode is set to OFF.  If it is set to anything else (mine had gotten set to CW) then your QCX will start to transmit after the power up splash screen is cleared.

Robb N2VJO