Date   

Re: My first time QCX build - fail.

Curt wb8yyy
 

Jim

I strongly suggest not transmitting until the receiver is working. Unplug the key or paddle.

On my build I missed on solder connection in the audio section. I found the issue by turning on the alignment source, yes free test equipment already built in. I poked around and found my issue. Also as mentioned its easy to not get the enamel off the toroid connections.

You have enough test equipment,  please slow down and I think you may solve it.

Keep in touch

Curt


Re: Ideal Power Voltage

Curt wb8yyy
 

Tom

I suggest reading what is in the manual. Yes its honestly a 3 watt rig with 13.5 volts input. If you feed a slightly higher voltage only to the PA stage, you can gain a half s-unit at most. I suggest enjoying the class E xmtr as is, but if you must have 5 watts see the manual.

Curt


Re: Keyer issue. #problem

Tony McUmber
 

This may sound silly, but are you trying to key the QCX keyer with the signal from your MFJ keyer?.  May I suggest that you connect your existing key and paddles directly to the QCX keyer input and set the MFJ unit aside?

 

73, N0BPA

 

 

From: QRPLabs@groups.io [mailto:QRPLabs@groups.io] On Behalf Of Donald Gover
Sent: Monday, September 3, 2018 9:08 AM
To: QRPLabs@groups.io
Subject: [QRPLabs] Keyer issue. #problem

 

I see a number of topics addressing various issues with the Keyer but after trying all the various solutions I can't seem to solve mine. I have a MFJ-564b that seems to work flawlessly on my Elecraft KX3. If I measure the resistance and continuity of the contacts at the phone jack end, with no pressing of the paddles there is basically infinite resistance. However that being said, about 2 out of 10 times when I power up the QCX it is just stuck in sending steady Dah's. This only clears when I tap either of the paddles several times. Then the second thing that happens is if I hold down the Right Paddle to get a steady stream of Dah's it from time to time inserts a Dit, with no pressing of the Dit paddle. 

  I've tried different cables, made sure I have a dummy load connected and verified I'm in CW test mode. I've gone over the construction and looked for bridged or almost bridged connections and I don't see any. Also have double checked the components and they seem to be correctly positioned. Receive works well and is very sensitive. In transmit I get a solid 5 Watts out when connected to a LiFO battery. I'm starting to come down on the side of demonic possession but before calling an exorcist might anyone have a suggestion as to where to look for this vexing problem? 

  73, Donald L. Gover KC9ZMY  


Re: Keyer issue. #problem

Frank Waarsenburg
 

Donald,

You could try 1k pullup resistors from the paddle contacts to the +5V power supply. Maybe there is too much resistance to ground somehow.

73 de Frank PA3CNO


Op 3 sep. 2018 16:08 schreef Donald Gover <dlgover@...>:

I see a number of topics addressing various issues with the Keyer but after trying all the various solutions I can't seem to solve mine. I have a MFJ-564b that seems to work flawlessly on my Elecraft KX3. If I measure the resistance and continuity of the contacts at the phone jack end, with no pressing of the paddles there is basically infinite resistance. However that being said, about 2 out of 10 times when I power up the QCX it is just stuck in sending steady Dah's. This only clears when I tap either of the paddles several times. Then the second thing that happens is if I hold down the Right Paddle to get a steady stream of Dah's it from time to time inserts a Dit, with no pressing of the Dit paddle. 

  I've tried different cables, made sure I have a dummy load connected and verified I'm in CW test mode. I've gone over the construction and looked for bridged or almost bridged connections and I don't see any. Also have double checked the components and they seem to be correctly positioned. Receive works well and is very sensitive. In transmit I get a solid 5 Watts out when connected to a LiFO battery. I'm starting to come down on the side of demonic possession but before calling an exorcist might anyone have a suggestion as to where to look for this vexing problem? 

  73, Donald L. Gover KC9ZMY  


Re: Keyer issue. #problem

Dwatson4 <dwatson4@...>
 

A short in your keyer wire/plug?

Dwight C Watson

On Sep 3, 2018, at 10:08 AM, Donald Gover <dlgover@...> wrote:

I see a number of topics addressing various issues with the Keyer but after trying all the various solutions I can't seem to solve mine. I have a MFJ-564b that seems to work flawlessly on my Elecraft KX3. If I measure the resistance and continuity of the contacts at the phone jack end, with no pressing of the paddles there is basically infinite resistance. However that being said, about 2 out of 10 times when I power up the QCX it is just stuck in sending steady Dah's. This only clears when I tap either of the paddles several times. Then the second thing that happens is if I hold down the Right Paddle to get a steady stream of Dah's it from time to time inserts a Dit, with no pressing of the Dit paddle. 

  I've tried different cables, made sure I have a dummy load connected and verified I'm in CW test mode. I've gone over the construction and looked for bridged or almost bridged connections and I don't see any. Also have double checked the components and they seem to be correctly positioned. Receive works well and is very sensitive. In transmit I get a solid 5 Watts out when connected to a LiFO battery. I'm starting to come down on the side of demonic possession but before calling an exorcist might anyone have a suggestion as to where to look for this vexing problem? 

  73, Donald L. Gover KC9ZMY  


Keyer issue. #problem

Donald Gover
 

I see a number of topics addressing various issues with the Keyer but after trying all the various solutions I can't seem to solve mine. I have a MFJ-564b that seems to work flawlessly on my Elecraft KX3. If I measure the resistance and continuity of the contacts at the phone jack end, with no pressing of the paddles there is basically infinite resistance. However that being said, about 2 out of 10 times when I power up the QCX it is just stuck in sending steady Dah's. This only clears when I tap either of the paddles several times. Then the second thing that happens is if I hold down the Right Paddle to get a steady stream of Dah's it from time to time inserts a Dit, with no pressing of the Dit paddle. 

  I've tried different cables, made sure I have a dummy load connected and verified I'm in CW test mode. I've gone over the construction and looked for bridged or almost bridged connections and I don't see any. Also have double checked the components and they seem to be correctly positioned. Receive works well and is very sensitive. In transmit I get a solid 5 Watts out when connected to a LiFO battery. I'm starting to come down on the side of demonic possession but before calling an exorcist might anyone have a suggestion as to where to look for this vexing problem? 

  73, Donald L. Gover KC9ZMY  


Re: LM7805 Replacement #qcx #parts

Shirley Dulcey KE1L
 

The TLC272 is not a rail-to-rail capable op amp and can only supply
10mA. So it's not a full replacement for the TS922, though it may
suffice in this application. The TLV272 is rail-to-rail but can only
supply 7mA; it may also work. Both are inadequate for the final stage
because of the limited current capability.

On Mon, Sep 3, 2018 at 1:07 AM, Kārlis Goba <karlis.goba@gmail.com> wrote:
I think TLC272 should also do the job, except perhaps for the final
headphone stage. It's a similarly specced part, and is available in DIP.

Regarding the supply voltage, look at the lowermost right corner. There you
see (ok, it's an educated guess) all of opamps being supplied straight from
12V rail. Common sense tells that too, since the common mode voltage used in
the circuit is 5V.

Karlis


Re: QRP Labs postage stamps

Hans Summers
 

Hi Jim

We post 600-800 packages per month. A lot of money! 

73 Hans G0UPL 

On Sat, Sep 1, 2018, 17:33 Jim via Groups.Io <we5f=aol.com@groups.io> wrote:
How did you pull that one off, Hans?

The word about QRP Labs is definitely getting out!

73 de Jim KM5M


Re: LM7805 Replacement #qcx #parts

Kārlis Goba
 

I think TLC272 should also do the job, except perhaps for the final headphone stage. It's a similarly specced part, and is available in DIP.

Regarding the supply voltage, look at the lowermost right corner. There you see (ok, it's an educated guess) all of opamps being supplied straight from 12V rail. Common sense tells that too, since the common mode voltage used in the circuit is 5V.

Karlis


Re: LM7805 Replacement #qcx #parts

Shirley Dulcey KE1L
 

You are correct: the TS922 is now only available in SMD packages. You
would either have to find some NOS DIPs or use an SOIC to DIP adapter.

The other alternative is to find another suitable part. So far as I
can tell, the QCX schematic doesn't show what the power supply voltage
supplied to those ICs is, so I can't tell whether they are attached to
the nominally 12V input or to the 5V regulated output. If it's the
latter (which is suggested by the bias circuit seen on IC9) you could
use a lower voltage op amp such as the TLV2462, which is the op amp
that Adafruit sells to replace the TS922. It's a 2.7-6V op amp that
otherwise has similar specifications and the same pinout. IC10 (the
output amplifier) appears to be biased to run from the 12V rail so it
definitely should NOT be replaced by a lower voltage part.

On Sun, Sep 2, 2018 at 5:33 PM, John VA7JBE via Groups.Io
<va7jbe=yahoo.com@groups.io> wrote:
There's some great advice in this thread and replacing IC6-9 sounds like a
worthwhile mod, but I'm having a bit of trouble sourcing the TS922 in a DIP8
package. They seem to have been discontinued in favor of SMD packaging.
Does anyone know of a source for these or a substitute that's still in
production?

Cheers,

John VA7JBE


Ideal Power Voltage

Tom Gundlach <ks5x@...>
 

To get the best power output from QCX.


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Re: My first time QCX build - fail.

Jim - K9DD
 

I've made progress but it still isn't working right. I rewired T1 and reinstalled it. That fixed the loud tone but I caused more problems. I lifted a trace off the board from pin 4 of T1. It appears to me to go to the source of Q5 so I hooked it directly to it. It now seems to work but I can't hear anything but noise and clicking when on an antenna. Also, now when I key the transmitter I can barely hear it in another receiver where before it was a strong signal. I'm close to giving up. I no longer have test equipment except a DMM.


Re: LM7805 Replacement #qcx #parts

John VA7JBE
 

There's some great advice in this thread and replacing IC6-9 sounds like a worthwhile mod, but I'm having a bit of trouble sourcing the TS922 in a DIP8 package.  They seem to have been discontinued in favor of SMD packaging.  Does anyone know of a source for these or a substitute that's still in production?

Cheers,

John VA7JBE


Re: QCX Enclosure Modification Video (detailed) by Juddie WD8WV #case #qcx #encl

Karl Schwab
 

Great job on this video again Juddie with that CW switch plunger.  I did the same with mine, but I made my own plunger mod similar to yours.  I am interested now, in your "tilt up" stand that I can see in your video shots.  Can you describe how you did that?  Thanking you in advance and 73, de Karl, KO8S


Re: U3S on 630M "crashes" the system. #u3s #630m

danielu@upcnet.ro danielu@upcnet.ro
 

    I do not know if it helps, but I have encountered all sorts of resets ,frequency shift and blocking LCD with VFO signal generator transformed into TX WSPR in 28 and 14 Mhz. Now I'm feeding the three BS170 with two LM7805 in parallel and the rest with a single LM7805. I chose two LM7805 with the same voltage (4.98V) at 0.5A for parallel mounting without equalizing resistors. The secret I think is in the multilayer 0,47microfarad capacitors connected briefly between the input and the GND at each LM as recommended by the manufacturers. The LM7805 is better than any other 7805. Everything goes right now for days  with these  three LM sources powered by an single  ordinary SMPS 9V / 1.5A  wall type.   Obviously there are also 2 pieces short-mounted of 1000micro / 10V for each LM and a heater .

Best wishes!

 Daniel , 73  YO8SAK


Re: QCX tuning

jmh6@...
 

Hi Alan,

Academic??

ALL failures are an opportunity to learn and make a product more robust.

I am surprised no one has talked about bringing up the power in steps? Measuring things as we go up to full power.

From where I look, this would give up real data to look at in the event of failure.

Lots of fun :).

John Concord, NH

On Sun, 2 Sep 2018, Alan de G1FXB via Groups.Io wrote:

Hi Glenn,
I'm in defence of all Hans views as well. 
https://groups.io/g/QRPLabs/message/26421
(I keep pointing out his statement that he has never experienced a failure
of any prototypes and beyond to production testing.
Last was my Post https://groups.io/g/QRPLabs/message/26498)
What I'm trying to understand is the conditions that lead upto what appears
to be a one or two a week report of PA failure,
Is it always user abuse, and / or is there any easy solutions ?.
My posts:-
https://groups.io/g/QRPLabs/message/26420
 https://groups.io/g/QRPLabs/message/25533
https://groups.io/g/QRPLabs/message/25822
Putting it into perspective the QCX has celebrated it's first birthday
Best case, its perhaps 52 out of 5500 units built, equates to just over 1%
failure(?)
of the most heavily stressed and abused components of any transmitter.
(it's probably fair to assume that failure is likely to be under rather than
over reported,
many would just replace the components rather than post a question about it
here?)
It's academic, we will move on and soon have a new unit to talk about.  :-)
Alan
On 02/09/2018 16:44, Glen Leinweber wrote:
In defense of Hans,
I don't recall seeing a brag about QCX able to handle
infinite-SWR conditions. (ie: antenna short or open-circuit).

 I can see a dangerous scenario....
if you're using an open-circuit type outdoor antenna - one that
measures open-circuit resistance between driven
element and ground. An extreme example might be a kite-elevated
long wire. This type of antenna can attain
a considerable charge, and rise to very large DC voltage levels.
Then you attach this antenna to your radio. Could even be an
un-powered radio....
Ka-blooy!
The QCX has an output filter that nearly floats as far as DC is
concerned. It has a path through R43, a 120k resistor
to one of the four 74ACT00 logic gates - most likely in a logic
"high" state. If you measure the DC voltage at the
antenna connection terminals with a high-Z DC voltmeter, you'll
measure close to +5V.
I would ensure that any antenna has a DC path to ground, either
through a RF choke, or a resistor, to bleed off any
static charge. The QCX's 120k resistor path is too feeble to
serve as a reliable discharge. A charged antenna can
blow the finals nearly instantly when connected. There is no
over-voltage antenna protection in the QCX.

A loop-type antenna is safer from this scenario, but I'd still
include a discharge path from the loop to earth.


Re: QCX tuning

Alan de G1FXB
 

Hi Glenn,

I'm in defence of all Hans views as well.  https://groups.io/g/QRPLabs/message/26421
(I keep pointing out his statement that he has never experienced a failure of any prototypes and beyond to production testing.
Last was my Post https://groups.io/g/QRPLabs/message/26498)

What I'm trying to understand is the conditions that lead upto what appears to be a one or two a week report of PA failure,
Is it always user abuse, and / or is there any easy solutions ?.
My posts:-
https://groups.io/g/QRPLabs/message/26420
 https://groups.io/g/QRPLabs/message/25533
https://groups.io/g/QRPLabs/message/25822

Putting it into perspective the QCX has celebrated it's first birthday
Best case, its perhaps 52 out of 5500 units built, equates to just over 1% failure(?)
of the most heavily stressed and abused components of any transmitter.
(it's probably fair to assume that failure is likely to be under rather than over reported,
many would just replace the components rather than post a question about it here?)

It's academic, we will move on and soon have a new unit to talk about.  :-)


Alan


On 02/09/2018 16:44, Glen Leinweber wrote:
In defense of Hans,
I don't recall seeing a brag about QCX able to handle infinite-SWR conditions. (ie: antenna short or open-circuit).

 I can see a dangerous scenario....
if you're using an open-circuit type outdoor antenna - one that measures open-circuit resistance between driven
element and ground. An extreme example might be a kite-elevated long wire. This type of antenna can attain
a considerable charge, and rise to very large DC voltage levels.
Then you attach this antenna to your radio. Could even be an un-powered radio....
Ka-blooy!
The QCX has an output filter that nearly floats as far as DC is concerned. It has a path through R43, a 120k resistor
to one of the four 74ACT00 logic gates - most likely in a logic "high" state. If you measure the DC voltage at the
antenna connection terminals with a high-Z DC voltmeter, you'll measure close to +5V.
I would ensure that any antenna has a DC path to ground, either through a RF choke, or a resistor, to bleed off any
static charge. The QCX's 120k resistor path is too feeble to serve as a reliable discharge. A charged antenna can
blow the finals nearly instantly when connected. There is no over-voltage antenna protection in the QCX.

A loop-type antenna is safer from this scenario, but I'd still include a discharge path from the loop to earth.


Re: My first time QCX build - fail.

Gary Freeman
 

Oops, sorry.  I meant Jim, not Ted  :-)

72 de Gary W0ITT


Re: My first time QCX build - fail.

Gary Freeman
 

Ted - I had a similar experience.  Be sure you are using a stereo plug in the key jack.  The QCX requires one.  If you put in a mono plug it just keys the transmitter, and the tone you hear may be the side tone. 

After my build I heard a tone, so I took my time to carefully do the alignment steps.  That ruined my finals because they were on transmit for so long,  To make sure, when you're doing alignment just unplug the key from the jack and use the little onboard key.

I had to replace several transistors.

That may not be your problem, but it is one to avoid.

72 and good luck
Gary W0ITT

 


Re: QCX tuning

Glen Leinweber
 

In defense of Hans,
I don't recall seeing a brag about QCX able to handle infinite-SWR conditions. (ie: antenna short or open-circuit).

 I can see a dangerous scenario....
if you're using an open-circuit type outdoor antenna - one that measures open-circuit resistance between driven
element and ground. An extreme example might be a kite-elevated long wire. This type of antenna can attain
a considerable charge, and rise to very large DC voltage levels.
Then you attach this antenna to your radio. Could even be an un-powered radio....
Ka-blooy!
The QCX has an output filter that nearly floats as far as DC is concerned. It has a path through R43, a 120k resistor
to one of the four 74ACT00 logic gates - most likely in a logic "high" state. If you measure the DC voltage at the
antenna connection terminals with a high-Z DC voltmeter, you'll measure close to +5V.
I would ensure that any antenna has a DC path to ground, either through a RF choke, or a resistor, to bleed off any
static charge. The QCX's 120k resistor path is too feeble to serve as a reliable discharge. A charged antenna can
blow the finals nearly instantly when connected. There is no over-voltage antenna protection in the QCX.

A loop-type antenna is safer from this scenario, but I'd still include a discharge path from the loop to earth.