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Author Topic: New QRP Labs 5W CW Transceiver Kit.  (Read 9379 times)

Steve 7931

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Re: New QRP Labs 5W CW Transceiver Kit.
« Reply #60 on: October 26, 2017, 07:28:07 AM »
Gil

Liked what I found,  I have ordered one from Moonraker in the UK just now, so will take a week or so to get here.
Will try it out with my FT 817. And report back here.  Thanks for the recommendation.
Also the little speakers, Veho 360 arrived and working out fine wid the MTR 5 B.  Thanks
Steve

gil

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Re: New QRP Labs 5W CW Transceiver Kit.
« Reply #61 on: October 26, 2017, 07:32:29 AM »
Gil

Liked what I found,  I have ordered one from Moonraker in the UK just now, so will take a week or so to get here.
Will try it out with my FT 817. And report back here.  Thanks for the recommendation.
Also the little speakers, Veho 360 arrived and working out fine wid the MTR 5 B.  Thanks
Steve
Great. 17ft of ladder line plus 67ft of wire is all you need for a W3EDP...

Gil

Sent from my SM-G928F using Tapatalk


caulktel

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Re: New QRP Labs 5W CW Transceiver Kit.
« Reply #62 on: October 26, 2017, 09:38:34 AM »
I just ordered an AVR programmer, super cheap on Ebay:

https://www.ebay.com/itm/USBTiny-USBtinyISP-AVR-ISP-programmer-for-Arduino-bootloader-Meag2560-uno-r3/400368767664

Unfortunately, the missing C17 has to be 39nF, so Hans is sending me one..  :(

This postpones my video unfortunately, but then I will be able to add a bit on upgrading the firmware.

Gil.

Hi Gil,

I have that exact programmer, however I could never find it in AVRDudess or I should say AVRDudess never found it, that's why I ended up using a Arduino with a serial port. Everybody on the QRPLabs group is telling me it should have worked, maybe it will for you. It seems that my low power output is because of the output LPF caps, so now I have to find some higher voltage caps that will fit in the existing holes on the board. I'm not really happy about this, the right caps should have been included in the kit. I think I will concentrate on putting it in a enclosure while Hans figures out the bugs. I hope you get your cap soon.

Joel
N6ALT

gil

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Re: New QRP Labs 5W CW Transceiver Kit.
« Reply #63 on: October 26, 2017, 11:43:13 AM »

It seems that my low power output is because of the output LPF caps, so now I have to find some higher voltage caps that will fit in the existing holes on the board. I'm not really happy about this, the right caps should have been included in the kit.

Hi Joel, Which caps are those?

Gil
« Last Edit: October 26, 2017, 11:45:42 AM by gil »

caulktel

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Re: New QRP Labs 5W CW Transceiver Kit.
« Reply #64 on: October 26, 2017, 12:46:23 PM »
Gil, they are C25-C28. In my case they are 2ea 390pf and 2ea 180pf. Apparently the ones provided are not high enough voltage rating and are heating up during Zmit and are responsible for low power output. I'm not sure I agree with this theory, because they are 50 volt caps and I have used them up to 7-8 watts without any trouble. I think somebody is grasping at straws. In any case a lot of people are having the 1.6 watt output problem and Hans needs to get to the bottom of it.

Joel
N6ALT

gil

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Re: New QRP Labs 5W CW Transceiver Kit.
« Reply #65 on: October 26, 2017, 03:12:38 PM »
Quote
In any case a lot of people are having the 1.6 watt output problem and Hans needs to get to the bottom of it.

Darn, I hope I don't have that issue... We'll see. I wonder if Hans got the idea of using three BS-170 transistors as finals like Steve Weber does for his MTRs... Why reinvent the wheel... Steve has no trouble getting 5-6W out of those little guys though...

Gil.

cockpitbob

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Re: New QRP Labs 5W CW Transceiver Kit.
« Reply #66 on: October 26, 2017, 04:48:01 PM »
Gil, they are C25-C28. In my case they are 2ea 390pf and 2ea 180pf. Apparently the ones provided are not high enough voltage rating and are heating up during Zmit and are responsible for low power output. I'm not sure I agree with this theory, because they are 50 volt caps and I have used them up to 7-8 watts without any trouble. I think somebody is grasping at straws. In any case a lot of people are having the 1.6 watt output problem and Hans needs to get to the bottom of it.

Joel
N6ALT

I too doubt it's the voltage.  If they are heating up it's their ESR (equivalent series resistance).  There's a lot of AC current flowing through the Tx filter capacitors.

ESR is determined by the dielectric used.  From good to bad, the common dielectrics are:
  NPO and Mica:  Either is the good stuff.  Almost zero ESR.  Very stable(doesn't drift with time, temperature, voltage).  Can't get them in large values though.

  X7R:  Most commonly used. ESR 25 times greater than NPO.  Used when 2nd best is fine.

  X5R:  Same as X7R but not quite as stable.

  Y5U:  Cheap stuff, but you can get large values in a small package.  ESR 2X worse than X7R.  Changes value like crazy: temperature, frequency, DC voltage.  Put 48V on a 50V capacitor and its capacitance goes down by 80%.  Seriously, a 1u cap becomes 0.2u.

For a Tx filter I would NEVER use anything but NPO or mica capacitors.


EDIT:  I just looked at my 80M filter bag and I can't tell what type of capacitors are in there.  I guess if my power is low I'll just swap all of them with NPO caps
« Last Edit: October 26, 2017, 04:57:13 PM by cockpitbob »

gil

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Re: New QRP Labs 5W CW Transceiver Kit.
« Reply #67 on: November 14, 2017, 03:48:45 AM »

Gil.

fmradio_man

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Re: New QRP Labs 5W CW Transceiver Kit.
« Reply #68 on: December 16, 2017, 05:42:35 PM »
I got my QCX yesterday.Three and one half hours later it was up and running on 40 meters. Impressed with the features too. I was missing a 10uf capacitor but I had tons in stock. Couple of notes:
1) Backlight brightness a little too bright. Maybe okay for daylight use. The 270 ohm resistor on pin 15 of the display could be raised to 4.7k or a 10k pot/switch could be added. Current drain reduced from 120 ma to 93 ma. Still sufficient for daytime use.
2) Had to move the L6 choke so the processor would not lock up on powerup. (according to their mods page)
3) For 40 and 80 meters the T1 toroid is a little hard to wind without messing up the turns and getting all the secondaries lined up. I found that some fingernail polish on the windings will hold the turns in place while winding and mounting. I also used tweezers to carefully push wires into the proper pads. Just don't forget to strip leads sufficiently.

I haven't had a chance to check the transmitter section for purity and modification suggested by the website mods page.

All in all, a great little addition to my collection.
Rick
« Last Edit: December 16, 2017, 07:06:47 PM by fmradio_man »