Date   

Re: 10W Linear Bias Setting

ajparent1/kb1gmx
 

That is what is written in the manual.
It is correct.  

Keep in mind the power input needs to be around 25-35 milliwatts
MAX for full output.

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


Re: QRP Field Day

ajparent1/kb1gmx
 

For solar and enough to run QCX...

A 20W panel is cheap.  One with a internal charge controller for the battery in use 
can be had.  Note; most with built in charge controller are for SLA/Gell/AGM
basically lead acid.  However a 7-8AH gell cell will run a QCX for days and
a 20W with charge controller will keep it fully charged with a few hours
direct sun.

The usual 7-9ah gell cell is plenty of power at 12V and they are
common and cheap.  A 20W panel should not cost more than 
35-40$ (without charge controller), and with built in charge
controller 60$ would be high.  A stand alone charge controller
is maybe 35$.  

The advantage with a standalone charge controller is if its
RF noisy you can replace it and if large enough in capacity
you can use with with larger panel or several of the same in
parallel.

FYI for non lead acid batteries go for a 20W or larger panel without
charge controller and buy one design for the specific battery.  Those 
LiFePo4 batteries do not like the charge regimine used for LiPo and
even less so for the typical lead acid charge system same is true for 
Lithium tech (unless the Battery Management system allows it).

Myself I ran 100W for FD.  USed 150W of solar (70W, 50W, 2x 20W)
and  two lawn tractor batteries in parallel (U1 size) for about 60AH
and Morningstar sunguard controller (X2 as they are about 80W max).
Ran the full weekend with that many times.  The overnight is at reduced
power to allow for battery size.  The trick is enough solar to bring the
battery up on as there is sun.  When there is sun there is enough
solar to sustain 100W (actually 230W DC consumption for the
radio).

I use them as I get typically 4-5 years (if kept correctly charged)
from them and they are lighter than one 60Ah battery plus they
are generally cheap most places under 40$(US)

FYI the home station is fully run by 480W of solar and a 150Ah
flooded NiCd industrial battery...  I never run out of power.

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


Re: QRP Field Day

Ted
 

Gwen,

I looked at your blog item about these packs. One thing I did not understand was the reference to 
 a QC "magic cable" I bought pre-made on Amazon.”

I’m dense but I don’t understand.  What is this about?

Ted

W7PO

On Mon, Jun 28, 2021 at 08:48 Gwen Patton <ardrhi@...> wrote:


You can find all the particulars on my ham blog, at https://www.ng3p.com. I also have some links to suitable power banks, though if you're in VK-land, you might have better luck looking for them locally.


Re: QRP Field Day

Tony McUmber
 

Got my Ray-O-Vac solar battery charger at Wal-Mart.  It is a flat plastic assembly with a long pair of wires hanging out the back.  Ready to mount.  Just point it at the sun and attach the wires to a battery.  Puts out about 13V.  Small 12-Volt gel-cel also available.  Both from Wal-Mart sporting goods dept.

Enjoy! The charger will keep things going all day, and the battery all night.  Don't forget to break for snacks occasionally.

73, Tony N0BPA


Re: Antenna Length with Insulated Wire

Stephen Sherer
 

Paul,
Thanks for asking this question. I know there are many new radio operators who don't know this. I hope I can explain the answer to your question in such a way that you and others are left with an understanding of why the 468/F is just a guestimate. The others who mentioned that each wire antenna must be fine tuned for center frequency for the section of band width you plan on using are indeed correct.

First, where did this 468\F in megahertz come from?

The answer is this: The experts of the day, way back when, meaning some time around the time the ARRL began publishing the "ARRL Antenna Book" and began compiling all the data and experiments regarding the building of antennas. Something needed to be used as a bench mark so the rest of us could begin to understand how to cut antennas to resonance. The engineers and other experts of the day had to start some where. They knew this would never be the exact number for any other antenna. Because we all know each antenna must contend with different nearby objects, differences in soil and so on.

Many years ago through hapen-stance while researching somthing else. I read an article about this very subjuct.

According to the article the 468/F was derived from an experiment to start a standard or guide to go by that would be easy to remember and in most cases in general be useful information for determining the approximate length of the antenna wire to be cut, knowing that in many instances or most, this would guide the antenna builder to have an antenna length slightly too long that would eventually require shortening the wires to fine tune the final wire length to attain the resonant frequency desired.

The experiment used 12 guage insulated wire of an unpublished velocity factor so that no one could ever say the information was incorrect. At the same time this is perfect. The only purpose of the 468/F was to give the antenna builder "a place to start". The actual velocity factor could be extrapolated This is not necessary. It's just a guide, a starting point from where one begins the final tuning.

As such, if you want the real number to use that works every time and takes out all of the confusion, this is the number I use when calculating antenna length. With bare un-insulated wire it has always been spot on with no other trimming necessary. Bare wire for practicle purposes, does not need a velocity factor when cutting for the low swr point.

I prefer to use insulated wire for several reasons but I don't want to get in to that here.

The real "un-bastardized" number to use for cutting antennas to resonance with some precision is:

         (1005/F mHz)(velocity factor of the insulated wire) = One wavelength in feet.

This number is published in the "ARRL Antenna Book". But never explained. I have only seen this number as far as I recall, in one place in the antenna book. As such this number has gone mostly unnoticed. 

It is with this knowledge that I can cut an antenna correctly the first time with insulated wire and not know the velocity factor of the wire. But, the process I will explain below will help you derive the exact velocity factor of the wire. This is important because no matter what insulated wire is used one never knows what the velocity factor is, even the published numbers by the manufacturers are just "close". Mostly you can't find this information and you don't need it.

Here is an example:

Cut your dipole legs using a specific frequency, lets say 7.150 mHz. Do not worry what the velocity factor of the insulated wire is, you will find that out. 

Here we go: 1005/7.150 = 140.6 feet is one wavelength.

When this number is used to "cut" the wire length of INSULATED wire, the antenna will always be just a little long. And this is what you want, you will never cut your wire lengths too short. Always just a little long.

I place the antenna about 6 feet off the ground so I can still reach it. Adjust my tranciever to the lowest power setting. Set the requency dial to 7.150 mHz.

Now we trim the antenna to resonance for 7.150. Start by rotating the VFO down in frequency until you see a one to one match, or close to it. Note the new frequency. For the sake of discussion, lets say the one to one match after the first adjustment is at 7.135 mHz not 7.150 which is where we want the antenna to be resonant. This means the antenna is too long, but we knew this would be the case in advance.

Begin trimming equal lengths of wire off each end of the dipole, start with one inch. Stop here, and go to the radio and now rotate the VFO up in frequency until one to one SWR is reached. Let's say the frequency changed to: 7.138 mhz. We are now slowly an inch at a time closing the gap to find the correct wire length for 7.150. Continue trimming the wire an inch at a time, then rotate the VFO "up" to the next one to one SWR point. As the antenna gets shorter the one to one SWR point goes UP in frequency. Stop cutting when you reach 7.150 at the one to one SWR point.

Its a good thing you kept track of how much wire was trimmed of from the initial wire length of 140.6 feet. For example let's say the wire length is now 130 feet long when the one to one SWR point is reached at 7.150.

Find the velocity factor : 130 / 140 = 0.9285. This is the velocity factor for this spool of wire in this location with the feed line length you are using and all interconnected equipment between the antenna and the tranciever.

Then notate the velocity factor for that "Batch" or "spool" of wire. This makes cutting subsequent antenna lengths easier and more precise the first time.

The final one to one SWR point has still not been determined.......were almost there.

Final Tuning:

Raise the antenna to its final fixed location and to the height you will keep the antenna. Notate the frequency with the one to one SWR point before you raise the antenna to its final installed height. Once the antenna is raised to the final height. Go back to the radio and check the one to one SWR point. You will find the frequency which has the one to one SWR point has changed it is no longer 7.150.  " This means that when you think your getting close to the desired frequency begin raising the antenna to its final height for the last few cuts."

Remember we are tuning the entire "system". The antenna, all interconnected equipment in the shack, feedline, soil characteristics, effect of nearby objects and...the height of the antenna above ground.

And that is the rest of the story.


Re: QCX Mini for 17M - usability on 20M & 15M? #qcxmini

ajparent1/kb1gmx
 

Just changing the capacitance i the LPF is a very poor way to go up in frequency.

Using the 17M filter would be fine for maybe 20/17 radio but going to 15M
is pushing it.

You do have to deal with L4 and C30 as that will be very inefficient on
any other band beyond what its tuned for.  If the efficiency is too
poor the BS170s are likely to overheat and fail.

T1 can be altered to tune a wider range.  Again 20/17 is reasonable
adding 15 means changes.


Allison
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Re: Shortage of Si5351A

Paul WB6CXC (tech-blog: wb6cxc.com)
 

Jim, thanks for this.  I needed some '5351's and yes, the distributors were definitely out of stock.  I was able to use Chipmail (as "guest", no registration needed), and ordered 50 of the Chinese equivalents.  I will report back on the performance -- I'm especially interested in the spur filtering behavior.
--
Paul Elliott - WB6CXC


Re: QCX Mini for 17M - usability on 20M & 15M? #qcxmini

HF
 

Hi David,
Is there room in the Mini's filter to install a pair of those square posts with 0.1-inch spacing?  If yes, then maybe the capacitance in the filter could be changed when changing bands.  I'm quite keen to hear about what you do to achieve this and how well it works.  I wish to do something similar with my 17m Mini.
Cheers
Halden VE7UTS


Re: QRP Field Day

Gwen Patton
 

There are lots of small solar panels that are already set up with the necessary charge controller to charge a USB power bank. If you get a Power Delivery or Qualcomm Quick-Charge power bank (or two, one to use, one to charge) and the necessary trigger cable or circuit, you can use one of those power banks to power your QCX+ just fine. I've been doing it for over a year now, and others have replicated my work and achieved good results. That's one of the benefits of using a USB power bank for your radio's power -- there are lots of charging options already configured to work with it.

You can find all the particulars on my ham blog, at https://www.ng3p.com. I also have some links to suitable power banks, though if you're in VK-land, you might have better luck looking for them locally. Just make sure that the supported PD and/or QC output voltages contain 12V. I've found that my QCX (original, not +) works just fine on 1-1.5A. I tested it on my workbench's compromise antenna (a QRPGuys "no tune" 40m end-fed, run from my porch to a tree out front) and routinely get RBN responses from halfway across North America. I don't bother fellow hams with responding to my tests, they've got better things to do, so I just send testing calls for RBN to pick up and report. There are plenty of links and search terms on my blog for the special cables that will request the power you require from the power bank and pass it on to your radio. (This is NOT a buck-boost circuit. There's no RF birdie generated by the cable's circuitry.) The blog also points to a recent presentation on this system that I gave to my local ham radio club.

I usually bring either a Wolf River Coils vertical, a different end-fed wire with a built in QRP tuner, or my 40/30/20 pre-tuned linked dipole when I work in the field. I bring an Elecraft T1 tuner, though I rarely need to use it, and an MFJ color display antenna analyzer to make sure the Wolf River vertical is tuned properly. My goal is to build the QCX-mini I have waiting on my bench, make a custom antenna for it, pre-cut for the band segment I want to use, and a dedicated PD or QC power bank. For that setup, I plan to do what you did, and use field expedient support systems (aka "trees") whenever possible, though I do have a couple of 7.2m telescoping fishing poles. One of them, some micro-paracord, and a few thick wire stakes would do just fine as the high end of an end-fed, or the center of a dipole. I have 150 feet of Kev-Flex wire I've been saving for an antenna that needs a lot of tensile strength, and given that Kev-Flex is tinned copper wire wrapped around a Kevlar core, it should work well for a 40m dipole.

-=-=-=-=-=-=-=-=-
73,
Gwen, NG3P


Re: QRP Field Day

K9NUD-Steve
 

My home power setup is a set of four solar panels that charge a LiFePO battery harvested from a wind farm. I have it set up with 24v battery power and I use a buck converter at my desk to get it to 13.8V for the radios, lighting, and soon the PC. I am building a power wall using a bunch of harvested 18650 cells in stacked boards (Jehu Garcia design). This will likely replace the LiFePO battery, which appears to have a bad cell or two.

I have an inverter, but it puts out a ton of RFI. I'd prefer to run everything using DC to avoid conversion losses. Modern PC monitors often have a 12V input, and I can run my laptop from a USB-C board connected to the 24V feed. The goal is to have the entire shack on solar/battery. 

I run the QCX Mini from a smaller 12.6V 3S board. It also stacks, so I went the whole weekend on that battery pack.


Re: QRP Field Day

wa8yan.radio
 

Amen!  Me too !



Sent from my Verizon, Samsung Galaxy smartphone


-------- Original message --------
From: VK5EEE <vk5eee@...>
Date: 6/28/21 2:38 AM (GMT-05:00)
To: QRPLabs@groups.io
Subject: Re: [QRPLabs] QRP Field Day

Can anyone recommend reliable solar panels that can be portable but also used long term at QTH and what they could best charge with QCX? And where to get the entire set up (panels, batteries, charger circuitry)? Or what various options there are, where can I do some reading into this and options? New to all this, thanks.

On 28 Jun 2021, at 04:47, Tony McUmber <1tonymc@...> wrote:

Great fun, yes?

I don't exactly have a go kit, but I can collect coax, a Z-match, 2 X QCX+ (40, 20), a random sort of dipole I use for both bands (straight for 40, with Z-match for 20, a solar game-camera charger and a 12-V gel-cell battery along with assorted odds and ends into a standard briefcase and a small canvas grocery bag.  Hauled all of this to my screened-in porch (for 'roughing-it' effect), and threw up the antenna between a couple of trees.  Made 100 contacts between the two, with bonus points for solar power.  Great fun, yes!

p.s - I copied the FD message from ARRL also, with a little help from the QCX+ decoder.


--
Love 30m and CW?
http://www.30cw.net


Re: QCX Mini for 17M - usability on 20M & 15M? #qcxmini

Ian MM0GYX
 

Oops, I talked about return loss but didn't copy the correct screengrab, here's return loss and transmission from Elsie:


Re: QCX Mini for 17M - usability on 20M & 15M? #qcxmini

Ian MM0GYX
 

Dave,

Maybe you are familiar with a program called Elsie, if not, it makes designing various filters quite straightforward. W3NQN mentions it when he wrote the article in QST about his BPF design using trifilar and quadrifilar resonators. Anyway, it's available for free download from Tonne Software, you may find it helpful.

I don't have a QCX mini, but I notice the kit uses the standard W3NQN design LPF for 17m, see the screenshot below. Assuming the LPF is terminated at each end with 50 ohms (which is what this design implies) you can see that it would have good return loss upto 17m band, but things look less good as you approach 15m. It's possible 20m 2nd harmonic suppresion may not be adequate possibly.



You could try it, but you might like to monitor for that emissions problem associated with 20m band (I don't know the strength of the 2nd harmonic without the LPF, maybe the 17m filter would be okay, until measured, who knows?), but perhaps there's an alternative? This cauer-ised version of the 17m filter might suite you better, it certainly would be a better choice 17m LPF for running up to 15m, return loss looks okay. http://www.gqrp.com/Datasheet_W3NQN.pdf

Good luck.

Ian MM0GYX


Re: QCX Mini for 17M - usability on 20M & 15M? #qcxmini

Daimon Tilley
 

I cannot comment on your specific band query, but I can tell you that following a facebook post by another OM, I tried my 20m QCX Mini on 30m and it works beautifully on both. My original QCX 40  was no good on 60 or 30m however. Hope that helps a bit unless someone can give you a definitive. 


Re: QCX Challenge - June 2021

N3MNT
 

US is very quiet this am.  Guess everyone is radioed out from FD.


Re: ProgRock serial interface

Syd
 

Thanks, that's what I did. Good to know anyway.
syd/wt1v


Re: QCX Mini for 17M - usability on 20M & 15M? #qcxmini

David Feldman <wb0gaz@...>
 

If some person with 17M QCX MINI wishes to perform experiment and consider result, that will be helpful!

I think three basic parameters of interest:

1. Receive MDS (minimum detectable signal)
2. Transmit spectral purity (harmonics and possible other spurious output)
3. DC power consumption during transmit (to see if thermal artifact in final amplifier stage due to efficiency change)

Approximate frequency ratio 18.1/14.0 = 29%, 21.0/18.1 = 16%

I do not expect optimization of performance, just curious circuit survivability and basic usability at reduced specification (=better than carry 3 radios!)

73 Dave WB0GAZ wb0gaz@...


Re: QCX Challenge - June 2021

John Pagett G4YTJ
 

I hope to be on 40m for the 1300z session.
73
John
G4YTJ 

On 27 Jun 2021, at 19:19, ON7DQ Luc <on7dq@...> wrote:

Hi Folks,

Sorry for the late announcement, but I just came home from a short SOTA tour.

Tomorrow is the last monday of June, so it's time for the QCX Challenge, see
http://www.qrp-labs.com/party.html

Not sure if I will be in the 1300Z sesion, but I should be QRV for the 1900Z one.
You all have fun !
 
73,
Luc ON7DQ


Re: QCX Mini for 17M - usability on 20M & 15M? #qcxmini

Curt wb8yyy
 

Dave

If you examine multiband rigs you will see that they employ a low pass filter typically for 2 adjacent bands. When properly adjusted for harmonic suppression I suspect in should do 20m. On 15m it would be operating into mismatch not ideal. Best way to see this is looking at filter response for the 17m filter, the rsgb article referenced by Hans may have the plots.  The tuning of the class E transmitter is another factor. Receive on 15m might be reasonable with just a few dB of loss. 

Curt


Re: QRP Field Day

 

Can anyone recommend reliable solar panels that can be portable but also used long term at QTH and what they could best charge with QCX? And where to get the entire set up (panels, batteries, charger circuitry)? Or what various options there are, where can I do some reading into this and options? New to all this, thanks.

On 28 Jun 2021, at 04:47, Tony McUmber <1tonymc@...> wrote:

Great fun, yes?

I don't exactly have a go kit, but I can collect coax, a Z-match, 2 X QCX+ (40, 20), a random sort of dipole I use for both bands (straight for 40, with Z-match for 20, a solar game-camera charger and a 12-V gel-cell battery along with assorted odds and ends into a standard briefcase and a small canvas grocery bag.  Hauled all of this to my screened-in porch (for 'roughing-it' effect), and threw up the antenna between a couple of trees.  Made 100 contacts between the two, with bonus points for solar power.  Great fun, yes!

p.s - I copied the FD message from ARRL also, with a little help from the QCX+ decoder.


--
Love 30m and CW?
http://www.30cw.net