Date   

QCX was working, now blank lighted screen, VR very hot, Advice?

Daniel Curtin KF4AV
 

My QCX was working except for low output power (about 1/2 W.) I was testing for RF output, and getting some. All of a sudden all went off. Now when I apply power LCD lights up, but adjusting R47 has no effect. Voltage on pin 3 varies from low to around 5V as R47 is adjusted. As per troubleshooting guide, I checked voltage on pin 3 and confirmed continuity for all the other pins (even thought they must have been OK earlier.) The VR has proper voltage on all pins. It seems hot, but I hadn't touched it before. I don't see any obviously damaged parts.

I will try walking through the various voltage readings, but would anyone suggest where to start? Have I fried the microcontroller? How to tell? I did bent a couple pins when I first put it in but they look OK.

I am learning a lot, and I am still hoping to do more study of it with my new scope.

73 Dan


Re: 49:1 End Fed antenna From 50 Watt Amp Parts

Donald Sanders
 

Many years ago a buddy and I made a Cantenna Antenna by adding a half wave wire each band for 80 and 40. We set the cantenna up in a tree about 30 feet above ground and the wires as inverted vee and separated 90 degrees. Compared to a regular dual band 80/40 dipoles at about 35 feet the Cantenna ant was usable but receiving stations noted about 2 "S" units lower signal. Still, a good emergency or backup antenna for local work. All Band - No Tuner required. Not recommended for QRP. 
Dr. Don W4BWS

God Bless All

Ham Radio does not make the world go round.
Ham Radio is what makes the ride worthwhile.


On Wed, Apr 22, 2020 at 5:23 AM George Korper <georgekorper@...> wrote:
Tom,

There is no comparison between a resonant full length End Fed  antenna and the MAXCOM. 
They are two very different ideas.

That being said, as I have discussed in other posts describing installations around the world
that are built to pick up signals from what you would call a dummy load, you may not have all the facts
on why such as system can and does prove useful.  It is a system and process that may not be suitable for Amateurs and the marketing
claims of companies outside their use in government can be exaggerated and are not the responsibility of government agencies to refute.

Best 73,
K3GK









Re: kit GPS QLG1 #gps

Hans Summers
 

Hi Gilles

It is indeed strange that a problem would afflict 3 units. 

I wondered also about what power supply you are using? If it was a very noisy switched mode supply I wonder if that could interfere with the RF reception? 

73 Hans G0UPL
http://qrp-labs.com

On Wed, Apr 22, 2020 at 4:35 PM Roger Hill <rhill@...> wrote:

Hi Gilles:

Seems to me there might be something done consistently, but incorrectly. It would IMHO be unlikely to have three kits with all the same problem. Maybe check carefully that the internal antenna is placed and connected correctly, and perhaps that the battery is installed right way up...

73

Roger

G3YTN

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***************************
Roger Hill
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On 2020-04-22 09:17, F1BFU - Fr - 79 wrote:

Hi my friends

I changed my GPS; I connected a GPS with an external antenna and everything is fine.
I will try to unsolder the GPS antenna of my QLG1 Kits and replace with an SMA socket. So I could hook them up to the GPA antenna and see if they all work properly.
Thank you all for your responses.

Gilles F1BFU / Fr


Re: kit GPS QLG1 #gps

Roger Hill
 

Hi Gilles:

Seems to me there might be something done consistently, but incorrectly. It would IMHO be unlikely to have three kits with all the same problem. Maybe check carefully that the internal antenna is placed and connected correctly, and perhaps that the battery is installed right way up...

73

Roger

G3YTN

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***************************
Roger Hill
***************************


On 2020-04-22 09:17, F1BFU - Fr - 79 wrote:

Hi my friends

I changed my GPS; I connected a GPS with an external antenna and everything is fine.
I will try to unsolder the GPS antenna of my QLG1 Kits and replace with an SMA socket. So I could hook them up to the GPA antenna and see if they all work properly.
Thank you all for your responses.

Gilles F1BFU / Fr


Re: kit GPS QLG1 #gps

F1BFU - Fr - 79
 

Hi my friends

I changed my GPS; I connected a GPS with an external antenna and everything is fine.
I will try to unsolder the GPS antenna of my QLG1 Kits and replace with an SMA socket. So I could hook them up to the GPA antenna and see if they all work properly.
Thank you all for your responses.

Gilles F1BFU / Fr


Re: Nickel Metal Hydride Batteries for QCX

George Korper
 

I lost the question about the Sony. It was the Sony 2010, which has been discontinued. 
If you can find a used one on Ebay that is working, nothing compares to it.

Thus I am working on the portable QCX, and that is OK because I don't need SSB.

Used to need it, but now I use Remote Hams for that.

CW is always fresh! A small telescopic whip works fine on 20, and actually, I can remove the LCD, and listen on a 9 volt battery I guess. 
We will see ! Gonna try today. 
















































Re: QCX 20 low output 5w at drain 1/3 w at output #problem

Daniel Curtin KF4AV
 

Ron,

Thanks. I did just see that suggestion in the Troubleshooting guide- I should have read it more carefully, but your extra details are very helpful. I will try it today! I am pretty sure the caps are correct, though reading them on the board is a challenge!!

Cheers, Dan


Re: Nickel Metal Hydride Batteries for QCX

George Korper
 

All these post have been great. So if charging is critical, and one at a time is best, or more if possible,
who has a

link

to a charger that is reliable and proven for NiMh batteries. Because the fact is I have the time to keep them on the
shelf. Ready for all those devices that take AA and AAA...like my numerous "Clickers" (remotes), keyboards, bluetooth headsets and potentially the QCX. 


Re: QLG1 GPS Receiver kit

Jonathan Dog
 

Andrew --

Lovely!

Another alternative is to replace the 74act08 with 74act00, which will give inverted values on the four-pin header (won't work if you're using RXD on the six-pin header). The LED drive gets double-negated. I accept it's more silicon, but it is less solder!

If the cable is long, worth using a proper driver. If the cable is short, use whatever is closest to hand.

Kind regards
Jonathan


Re: Nickel Metal Hydride Batteries for QCX

George Korper
 

Wow, Jim, that is a very useful post. I would very much like to see a picture of your 
QCX because it sounds exactly like something I would like to do! If you have the time,
please post a pix. 


Re: 49:1 End Fed antenna From 50 Watt Amp Parts

George Korper
 

Tom,

There is no comparison between a resonant full length End Fed  antenna and the MAXCOM. 
They are two very different ideas.

That being said, as I have discussed in other posts describing installations around the world
that are built to pick up signals from what you would call a dummy load, you may not have all the facts
on why such as system can and does prove useful.  It is a system and process that may not be suitable for Amateurs and the marketing
claims of companies outside their use in government can be exaggerated and are not the responsibility of government agencies to refute.

Best 73,
K3GK









Re: QLG1 GPS Receiver kit

Andrew Lenton
 

Hi Keeping it simple,

 

TTL is a positive going 5V or 3V3 signal (positive = 1)

RS232 is -12 of logic 1 and + 12 for logic zero. (this was used to get data through longish cables, no idea why -12 is a 1, historic)

 

If you invert TTL through a single transistor it will work on a RS 232 interface.

 

 

73 Andrew


Re: 49:1 End Fed antenna From 50 Watt Amp Parts

TomW4OKW
 

Gary, N3GO said:

A company in Florida once dazzled the Army back in the ‘70’s or 80’s with a compact 2-30 MHz dipole targeting the Manpack market as I recall. They made a similar claim... Something like 1.5:1 SWR over the entire range.

  It didn’t take a lot of effort to reverse engineer the design... essentially a short dipole as advertised, shunted at the feed point with a 50 ohm power dissipating resistor. i.e. a leaky dummy load of sorts. Indeed... no tuner required. Don’t you just love the creativity of marketing?   Truth in advertising at its best. LOL!

Tom sez:  The "MAXCOM automatic antenna matcher". And they sold millions of them to thegovernment, who wanted "no tune" antennas for Embassies, MARS and the military. They received OK, but most of your trasnsmit RF went up in heat!

73 Tom/W4OKW


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Re: kit GPS QLG1 #gps

KEN G4APB
 

Sorry Gilles, got interrupted before I finished...I was going to say for a first start-up of a new gps unit to need to give it a good clear view of the sky to allow a new almanac to download, can take 15 minutes or so. Also you need to be seeing at least 25db c/n values for good data. Only when you have satisfied these conditions can we start to investigate the pps connection. Also check your versions with Hans earlier posts, there were some issued with a firmware problem.

73 Ken G4apb


Re: kit GPS QLG1 #gps

KEN G4APB
 

Hi Gilles,
more info please. Are you getting a lat/long coordinates indication on your U3S? Four stats sounds too low, you should be seeing many more. 

73 Ken


Re: QCX 20 low output 5w at drain 1/3 w at output #problem

Ronald Taylor
 

Dan, many have found that removing a couple of turns from each of the toroids L1-L3 can raise the power output of the QCX20. If you are sure you have DC continuity through all of them and getting some power output and all the capacitors are right, then I’d try that step next. Before you do it, recount the turns you have in there. Many people find one extra turn because they forgot to count all the wires running through the center of the core as one turn. At any rate all you have to do is lift one wire of each toroid and unwind a couple turns and resolder it without cutting. That’s easier if you have to add a turn back on to get it right. When it’s right trim the excess wire and solder it back in place. I’ve built or fixed for others several 20 meter QCXs and have only found one get close to 5 watts output. The average I’ve seen is about 3.5 watts. And that is plenty of QRP power on 20 meters and only about 1.5 dB less than 5 watts, or about 1/4 of an S unit. 

Good luck .... Ron

On Mon, Apr 20, 2020 at 16:18 Daniel Curtin KF4AV <danieljcurtin42@...> wrote:
My QCX seems to work fine on RX. On TX I get 5 w (on the internal meter)at the drain of the BS 170s but  at the end of L1 about .3 w out. The instructions indicate the LC circuit would be suspect I do have DC continuity through the Low Pass filter. As best I can see I have the right capacitors in the right places and the right number of turns on the toroids.

I just got a digital scope (my first scope) so I tried to signal trace. I list here P-P rf voltage, the scope gives lots of other info:

DC input is about 14 V, for these readings.

On both sides of C29 40 V (including input to L3)
On the output side of L3 20 V
On the output of L2 10 V
On the output of L1 and at the BNC connector 7 V

Am I looking at the right things? Could my toroids be too poorly wound (I have not wound any in years and never any so small.)

Any help appreciated. I am having great fun with this excellent kit, and already have learned a lot.

73 Dan KF4AV


Re: Status of the All-Mode, Multi-Band Transceiver Kit?

@CurtisM
 

Well you may need to define up to date. The ubitx is a bit different than a ft817, and a hit lower receive current draw. I have a v4 and it operates decently. You might research who has adapted it to transvert on higher frequencies, but its a huge reach for those bands you mention. Neither rig is exceptional on cw, but they work. Ft817 probably better for getting to those higher bands, see if anyone has modified a ubitx to reach up into uhf.

You can customize the ubitx, a huge plus.

73 curt wb8yyy


Re: Nickel Metal Hydride Batteries for QCX

James Daldry W4JED
 

Hi, George

I like lithium (all types) because they are dead simple to charge. Limit the current and limit the voltage to 4.2 for most, 3.8 for LiFePO4. Also, for 18650's, 3 cells is 12 volts, close enough for gummint work.

NiCads are second, because most will take charging abuse - if overcharged and grabbed before too hot to touch they'll survive the assault. You can also trickle charge NiCads at 1/10 C or less. Fast charge can be accomplished by either thermal cutoff or looking for voltage dip.

NiMH are a nightmare to charge. Put one on a trickle charge and tomorrow it will be dead. Over current on charge, dead. Let it get warm enough to feel while charging, dead. Since voltage droop at charge end is too small to measure, you have to monitor cell temperature and stop the charge on the first measurable temperature rise.

I have my QCX in a homemade transparent ABS case with an aluminum front panel, with 2 - 6 volt NiMH battery packs in the bottom of the box. I have a 1N4148 diode with a 1K resistor in series buried in each pack, with the diodes wired in series, so the charge stops immediately when the forward voltage drops. So far I haven't hosed the batteries.

73

Jim W4JED

On 4/21/20 1:35 PM, George Korper wrote:
Hi,

I use Nickel Metal Hydride and alkaline batteries with the QCX. 
They are very cheap these days, and less hazardous that Lithium and 
not restricted to carry on by TSA. They have little memory, and are pretty cheap. 
I like they are AA.

I use 20 volt Lithium batteries for the amp and love 'em but for a barefoot
QCX, the Nickel Metal Hydride or Alkaline seem sufficient. 

My question what are members in the Group feelings about these vs. Lithium. I know Lithium
batteries are  popular these days, but there are some drawbacks. What do you think?


George


Re: Nickel Metal Hydride Batteries for QCX

Lawrence
 

I agree.  NiMH and the now less used NiCd batteries are more rugged than Lithium based batteries but they still need to be managed and maintained correctly.  Simple chargers do tend to cause the packs to become unbalanced after a number of cycles and heavy discharge of an unbalanced pack can cause one or more cells to be reversed, overheat and possibly burst.

NiMH cells tend to be capable of handing high currents, deep discharge and light overcharging well but ideally these packs should have the individual cells monitored and charged individually just like Lithium cells and you will get long life.  In the model car world it is common to buy matched cells and to have a jig to recharge them individually and monitor to ensure each cell comes up to full.  This then allows very heavy discharge during racing without damaging the cells.

Common NiMH chargers are often just a trickle charger with a circuit to look for the negative dv/dt that indicates full but this is unreliable since the first battery to become full will show this behaviour and it does not mean ‘all’ the batteries are full.  Repeated cycling can leave some batteries quite undercharged leading to early death.

73 Lawrence Harris VA7EDU




On Apr 21, 2020, at 15:55, Shirley Dulcey KE1L <mark@...> wrote:

I have used them. My experiences are very different from yours. I have always recharged them individually, which may help, and I don't run them down all the way.

That said, my current main field battery is a BioEnno 3000 mAh LiFePo4.

On Tue, Apr 21, 2020 at 6:10 PM ajparent1/KB1GMX <kb1gmx@...> wrote:
Have you  actually used them?
I have and they are better but claims have not been fully met.
4 of the 12 never recharged after abut 30 cycles and one leaked.

Allison
-------------------------------
Please reply on list so we can share.
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Re: Nickel Metal Hydride Batteries for QCX

ken fest <disklog@...>
 

I have used Eneloop for years ( the original white ones ) in both AA and AAA sizes and have had zero failures. I like them so much
I now have them in all my devices that take AA or AAA.
At lease two dozen in use at this time with half dozen charged and sitting on a shelf waiting to be used. No leaks yet.
Ken

On Tuesday, April 21, 2020, 06:10:43 PM EDT, ajparent1/KB1GMX <kb1gmx@...> wrote:


Have you  actually used them?
I have and they are better but claims have not been fully met.
4 of the 12 never recharged after abut 30 cycles and one leaked.

Allison
-------------------------------
Please reply on list so we can share.
No direct email, it goes to bit bucket due address harvesting in groups.IO