Date   

Question about a different enclosure #qcx40 #enclosure

Darren KN4WML
 

I have a question maybe someone has run into. I'm building a 40m qcx+ in a different enclosure that's designed for this machine. My original 40m qcx has a page in the manual where it shows you the diagram for the connections to remotely move the dials & buttons.  Has anyone done the + model in an enclosure? Reason being I'm trying to figure which connections on the PCB board I should use. Mainly the 2 buttoms and the power button.   Any ideas or opinion would be appreciated......... thanks

Darren
KN4WML


Re: Wire size

The Crunchbird
 

Allison, Thanks for responding to my question. I guessed that the question must have been asked before which is why I apologized right up front for asking it. Anyway, the 31AWG made winding T1 on the QCX+ a breeze. It took me only about ten minutes to wind using the continuous winding technique Hans described in the instructions. 31AWG is indeed kind of small but most signal transformers I have seen use very thin wire. A case in point is a 455KHz IF transformer. Anyway, the way I see it, I have a good desoldering gun and I can always pop the sucker off the board and rewind it if I have to. Thanks again, Dave. N2SN ex G4FEB 


Case for GPS #case #clock #gps

Thomas O'Brien
 

I have just completed the Clock and GPS kits - worked the first time, (thank you).
I now have the aluminum case for Clock, which is very nice.  I'd like to put the GPS board in a convenient location.
Luckily, at my location I can get good GPS reception even a few feet from a window.
In choosing a separate enclosure for the GPS board, I ran some simple material tests.  Covering the GPS with a box lid of Polypropylene, one of High Density Polyethylene, and one of Polystyrene, I saw little or no reduction in signal strength as indicated by the Clock display.  So I'm going to sacrifice one of the small parts boxes to make a protective case for the GPS board.
There is a lot of spare room in the Clock case, so I'll try to come up with some good use for it.  Maybe a small breadboard.
Thanks to everyone on this board for the friendly comments and good advice.


Re: turning down the QCX power #qcx #supply

Mike Besemer - WM4B
 

I’m thinking of experimenting with resistance in series with L4, but need to get a round-tuit. 

 

Maybe someone has already been down that road and cares to share?

 

Mike

WM4B

 

From: QRPLabs@groups.io [mailto:QRPLabs@groups.io] On Behalf Of Brent DeWitt
Sent: Thursday, July 30, 2020 7:22 PM
To: QRPLabs@groups.io
Subject: [QRPLabs] turning down the QCX power #qcx #supply

 

I just replaced the 7805 voltage regulator on the QCX with an LM2940-5 LDO regulator, .I also bumped C37 up to 47uF for stability and still have the reverse polarity diode in place..  I was curious what it would take to turn down the output power to WSPR and 10 Watt linear input power levels.  On my 40 meter QCX, lowering the input DC to about 6.25 V brings the output power down to roughly 15 mW (scope measurement into 50 ohms).  The output still appears to be a pretty clean sine wave.  The LCD backlight starts to dim a bit, but still perfectly readable indoors.

Nothing ground breaking, just thought some might be interested.

73,
--
Brent DeWitt, AB1LF
Milford, MA


Re: #antenna #qrp-dx Gents - a guide for the Perplexed , and what's more Free. ARRL Antenna basics book. #antenna #qrp-dx

ajparent1/KB1GMX
 

Complain all you want the only ones that can do that is ARRL the publisher.
They can change it and you can't.

That and it was written a few years back.  Its old news.

As to velocity or propagation on 450ohm wire its easily measured. 
Hint its physical length over electrical length.  To measure that you
need some and a RF source and a way to detect resonance for the wire.
Its in the handbook.  Might even be in the copyrighted work.

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


turning down the QCX power #qcx #supply

Brent DeWitt
 

I just replaced the 7805 voltage regulator on the QCX with an LM2940-5 LDO regulator, .I also bumped C37 up to 47uF for stability and still have the reverse polarity diode in place..  I was curious what it would take to turn down the output power to WSPR and 10 Watt linear input power levels.  On my 40 meter QCX, lowering the input DC to about 6.25 V brings the output power down to roughly 15 mW (scope measurement into 50 ohms).  The output still appears to be a pretty clean sine wave.  The LCD backlight starts to dim a bit, but still perfectly readable indoors.

Nothing ground breaking, just thought some might be interested.

73,
--
Brent DeWitt, AB1LF
Milford, MA


Re: For sale: QCX40 & 50W amplifier

Jon <jon.ke5uru@...>
 

Just realized that my title may have created confusion...

This is a QCX radio on 40 meter band.  It is NOT a QCX+.

A better title is "QCX40 & 50W amplifier".


Re: For sale: QCX40 + 50W amplifier

K2DB Paul Mackanos
 

If it's still available I'll take it


On Thu, Jul 30, 2020, 4:03 PM Jon <jon.ke5uru@...> wrote:
For sale:
  • QCX40 that is assembled and working correctly
  • QRP Labs 50W amplifier w/case (not assembled)
  • QRP Labs 50 Ohm, 20W Dummy Load (assembled)
Asking $100 + $15 shipping in the continental US.

Please reply off list.


Re: #antenna #qrp-dx Gents - a guide for the Perplexed , and what's more Free. ARRL Antenna basics book. #antenna #qrp-dx

Timothy Fidler
 

I'd still like to see it covered in the book.  You can't leave good enough alone can you , Alison ? "The End fed zepp is nothing special " well it is something special c/with the Black magic and BS of EFHW and the magic counterpoise. By the way gents,
450 Z CCSW  twin seems to be the best wire topology  to use for the matching section. Unfortunately most vendors seem very dark on what the Vel of prop is and you don't want to by buying a bit of Migthy Fine Junk just to set up this one length... .life's  a bitch.  TEF
Another point of difference is that if you can get a 40m dipole in you can trap it and have a 40/20,  but with a Zepp as above you have to electrically switch the transformer leg to a shorter one to go to the higher frequency as well as put in a trap to reduce the RF electrical len of a the driven element.


Re: #antenna #qrp-dx Gents - a guide for the Perplexed , and what's more Free. ARRL Antenna basics book. #antenna #qrp-dx

ajparent1/KB1GMX
 

The End fed zepp is nothing special and the "phasing section" is not.
Its a quarter wave transformer to feed the high impedance end of the
half wave wire (one leg).

Performance save for feed point convenience is identical to that of a dipole.

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


Re: Wire size

ajparent1/KB1GMX
 

On average its asked once every 6 weeks.

You may find #31 a bit fine for handling.  However wit will work otherwise.
Yu may have to trim off a turn depending. 

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


Re: Advice re solar power?

ajparent1/KB1GMX
 

As someone that has long progressed to adoption of Lithium tech
its several things that have been the primary reason.

Good discharge curve and excellent high current capability.
Good shelf life for charged battery and large number of cycles over its life.
The winner is for the power its by far easily half the weight or less.

I have a 11AH pack for my FT817 and its under 2.3pounds, that is light
and small enough for a pocket.  Its a 3S4P configuration with battery
management board.  Why 3S, its in the sweet spot for the Ft817 power
needs.  The ft817 is a bit of an oddball as it can run on automotive power
(nominal 13.8V) its happy with as low as 9.6V.

For solar applications I found the mentioned 555 circuit poor.  I
use the MicroMT+  also 555 design but PWM and very good
with lead tech.  For Lithium over-votlage is not allowable so the
approach is a quiet switch mode CV/CC controlled
Current/constant Voltage.  This limits the current into the cells
to a safe value and the peak voltage is controlled
(no over charge). That also protects the radio if the
battery opened up or be came disconnected.

Added to that, MPPT is just finding the panel voltage where the
peak power occurs for the typical 36 cell panel (12V use) that
falls around 17.2 to 18.2V.    The easy way was to set the output
current to allow the panel to run at 17-18V and at the same time
take advantage of the power conversion.   For a typical 20W
panel that means 20W at 18V (1.11A) and the switching regulator
delivers to the battey (lead in this case) 13.8V at 1.3A (peak sunlight)
or about 18W of the total 20W.   Without switch mode conversion
you would only get something more like 15W.  Solar panels look
more like a constant current source at its short circuit current
(1.2A for most 20W panels) so you get less usable POWER.

That can work for larger panels if the charge current is acceptable.
A 50W panel will do 2.7a at 18V so with power conversion that can
easily be 3.2A at 13.8V which is just right for a 18-20Ah gell cell.
Going to 100W it works out as 5.5a@ 18V again with power
conversion we get 6.5A charge current at 13.8V just fright for a
60Ah battery.  For the higher power a commercial charge
controller MPPT can be found.  Not all Morningsar units are
quiet some version in the product line are.  Same for others.

I've found a suitable CC/CV converter (common and cheap) can
be made quiet if housed in metallic container with bypasses and
filtering at both input and output.  A mint tin proved both reasonable
size, cheap, and RF tight.  Its reasonable for the 20W case.

For portable work 20W solar and 7-10ah battery is the upper limit
unless your running a 100W radio and most of those are not light.

For powering something in the QCX power class 4-5W and 12-13V
Two Volkwagon panels at 3.2W each in parallel and a 3S2P pack
(5ah) with the above charge controller is small  light and more
than enough for a day.  The charge controller is matched to those
panels and puts out .43A at 12.6V which is for the pack a low
rate charge (C/3 would be about 1.6a).  Howeever the radio uses
less (barely 80ma on RX) so the battery is kept ahead of discharge
rate (.9 A peak .45A average TX 5W SSB).

Each case is optimised for run time or weight or working conditions.


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


Re: Advice re solar power?

ajparent1/KB1GMX
 

Crunchbird...

One error, fully charged they are 4.2V for a whopping 16.8V.
Once you runthem a bit depending on vendor the nominal is 
14.8V.  The yabut is that for LiPo...

The Lifepo4 flavor the full charge is 3.7V and nominal is 3.2V
much more friendly to QCX.  Full charge is 14.8 and nominal
voltage then would be 12.8V.

The problem there is there are about 3-4 major flavors of
Lithium rechargeable tech and they are all just a bit different.
The 18650 is the size of the common cylindrical lithium cell
and its chemistry can be at least one of several that are not
interchangeable.

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


For sale: QCX40 + 50W amplifier

Jon <jon.ke5uru@...>
 

For sale:
  • QCX40 that is assembled and working correctly
  • QRP Labs 50W amplifier w/case (not assembled)
  • QRP Labs 50 Ohm, 20W Dummy Load (assembled)
Asking $100 + $15 shipping in the continental US.

Please reply off list.


Re: Wire size

The Crunchbird
 

Evan, Thanks for the reply. I am putting the 40M version together and the 28 AWG is very hard to wind. I can't imagine what it would be like to wind that tiny toroid for 80M. I just found a spool of about two miles of 31AWG. I will wind T1 with it and get back to everyone if it works as I expect it to. Now I have to put up some kind of 40M antenna. I have been off the air for about eight years and had sold all my equipment mainly due to antenna restrictions. Today my house sits on 57 acres in rural NE Florida. I could likely run a quarter mile long end fed wire but I will likely settle for an end fed inverted L hung up a couple of pine trees to start off with. Dave. N2SN 


Re: #antenna #qrp-dx Gents - a guide for the Perplexed , and what's more Free. ARRL Antenna basics book. #antenna #qrp-dx

Jim Painter
 

Do a search in the group files for arrl.

Jim... kq3s


On Jul 30, 2020, at 9:35 AM, Podolsky A <w8du@...> wrote:

If you mean the files section of this group, I don't see that document there.
73 de Arnie W8DU


Re: Advice re solar power?

HF
 

Hi Ross,
I also use 4 Li-ion 18650 cells to power my QCX.  It's a little too much for day trips; if I did it again, I'd use the "AA" size cells. 
When I make a SOTA trip, I'm mostly concerned about mass because I'm getting soft in my old age.  If I carry a radio with more power requirements than a QCX, I take an LiFePO4 battery with enough capacity for my radio session.  That's easier to carry than a PV panel.
From your current requirements, it looks like your need for solar charging pertains to Field Day 2021 and that you plan to use a radio with about 100 W output.  That's what I did for 2020 FD.  I used a 15 Ah LiFePO4 battery and charged it from some PV panels.  It konked out a few hours after sundown so I had to charge it from my car.  Anticipating FD 2021 or an actual emergency with no automobile for backup, I have since purchased 3 additional 16 Ah LiFePO4 batteries for less money than I spent on my 15Ah battery (the first one is Bioenno; the recent 3 are Miady).  That should run the radio all night (running the ham all night is another matter).  For 2020 FD, I used a cheap buck converter charging module which gave only 3A of charge current; a little below my consumption rate.  For next year, I'll probably use either a high-current linear regulator or a 555 circuit like the one Erick cited.as my charge controller.  This sort of charge controller is less efficient because the PV panel operates away from its max power point.  But it's lightweight and cheap.  If lightweight and cheap don't matter in your application, then get a MPPT charge controller with genuine CE certification and verify its RFI on your favourite bands as soon as it arrives so you can send it back if it's noisy.
Consider using LiFePO4 batteries instead of the gel-cell.  A little internet searching will provide a list of reasons for this.
As for the PV panels, you have many choices.  Learn about I-V curves and how they change with illumination levels.  If you buy a cheapie panel, measure its actual performance while you still have the option to return it.
Cheers
Halden VE7UTS


Re: Deliveries for QCX+

Mitch NW0M
 

I'll provide a positive delivery transaction.  I ordered the QCX+ 40M with Enclosure on 7/14/2020 and received it 7/24/2020.  10 days!!!  

73, Mitch 


Re: #antenna #qrp-dx Gents - a guide for the Perplexed , and what's more Free. ARRL Antenna basics book. #antenna #qrp-dx

Alan de G1FXB
 

If you are already logged in a direct link should work;-
https://groups.io/g/QRPLabs/files/ARRL%20Basic%20Antennas.pdf


Alan

On 30/07/2020 14:35, Podolsky A wrote:
If you mean the files section of this group, I don't see that document there.
73 de Arnie W8DU

-- 
Smell Czech corruptions are inevitable


Re: Advice re solar power?

Roy VE7DH
 

If you are capable of and willing to do a little soldering you can build a very small and lightweight charger controller that has absolutely no RFI problems. It does not pull out every micro-watt of solar energy like a MPPT controller, but it is totally quiet.

http://mdpub.com/555Controller/

regards, Roy

11201 - 11220 of 61115