Date   

Re: For sale: QCX40 & 50W amplifier

Jon <jon.ke5uru@...>
 

Sold.


Re: Case for GPS #case #clock #gps

Bob Parr
 

This was one of the reasons I got a 3D printer.  I ended up making a slanted face box that holds a 4 line display, the clock and GPS.  I extended the buttons to recessed compartment on the back along with a 500 ohm pot to vary the brightness.  Took about 5 prints to dial everything in but turned out great.  I have been thinking about ways to make a two piece interlocking case because the GPS doesn't work well where I planned to put the clock.  We'll see if I get lazy and keep the clock in the current location or actually work on the new version


Re: #antenna #qrp-dx Gents - Rothammel's book #antenna #qrp-dx

John Rabson
 

For information on the Zepp, see sections 9.1.1.1.1 for the Zepp and 9.2.3 for the double-Zepp in the English edition of Rothammel’s Antenna Book (Krischke, DARC Verlag 2019).

John F5VLF

On 30 Jul 2020, at 23:39, Timothy Fidler <engstr@...> wrote:

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: turning down the QCX power #qcx #supply

ajparent1/KB1GMX
 

Resistance in series with L4 will upset the tuning and maybe lower power.
It will definately take the finals out of class E, not suggested.

One way is to isolate the DC feed to Q6 and run that voltage down.
Depending on the desired power at 9V mine is about 100mW.

The 7805 will regulate down to 7V below that it may be sketchy.

Allison
-------------------------------
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Re: QCX QRO Party

Peter GM0EUL
 

Excellent.  So I have three options:
Barefoot QCX
QCX driving Juma PA100-D
Homebrew valve tx with a qrplabs vfo.

I'm looking forward to it!

73
Peter GM0EUL




On Fri, 31 Jul 2020, 07:38 Hans Summers, <hans.summers@...> wrote:
I think everything should be welcome! To qualify as "QRP Labs" for the purposes of the QSO party, some part of the station used, should be a QRP Labs kit. 

73 Hans G0UPL

On Wed, Jul 29, 2020 at 10:03 PM Karl Schwab via groups.io <ktschwab=yahoo.com@groups.io> wrote:
Can I sneak in my HF Packer 40w amp???  73,de Karl, KO8S


Re: turning down the QCX power #qcx #supply

Alan G4ZFQ
 

I was curious what it would take to turn down the output power to WSPR and 10 Watt linear input power levels.
Brent,

Of course the U3S gives easy QRP and far more versatile WSPR options.
With the QCX you'd possibly get around 13dBm WSPR by bypassing the PA.
Otherwise I'd try an independent adjustable regulator for the PA, that would guarantee everything else worked normally.

73 Alan G4ZFQ


Re: QCX QRO Party

Hans Summers
 

I think everything should be welcome! To qualify as "QRP Labs" for the purposes of the QSO party, some part of the station used, should be a QRP Labs kit. 

73 Hans G0UPL

On Wed, Jul 29, 2020 at 10:03 PM Karl Schwab via groups.io <ktschwab=yahoo.com@groups.io> wrote:
Can I sneak in my HF Packer 40w amp???  73,de Karl, KO8S


Re: Advice re solar power?

The Crunchbird
 

Allison,

I agree with you about the different lithium technologies. I am guessing that you are an engineer as you are obviously a technical person. Dave. N2SN ex G4FEB


Re: Case for GPS #case #clock #gps

Tony McUmber
 

Moments ago I finished installing my new QLG1 board in a clear plastic crayon box I got from Wal-Mart.  It is exactly the right size, being 92mm X 70mm inside dimensions.  It is tall enough to accommodate the board with the nylon pillars attached and has a snap-on lid.  Works great!

Not being so great with the electronics construction, I got the mechanics down well.  An unqualified success, if you will.

Tony N0BPA


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
-------------------------------
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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