Date   
Re: ENAMEL REMOVAL

Braden Glett
 

I'll stay with a nice safe, sharp knife, thank you!!

Re: ENAMEL REMOVAL

Bill Cromwell
 

Laser Lab

protect your remaining eye

73,

Bill KU8H

On 6/11/19 8:43 AM, Stephen Farthing G0XAR JO92ON97 wrote:
Caustic soda of any variety will turn your flesh to soap. I dread to think what the molten variety would do to an eyeball.
Yours with both eyes shut and cringing at the thought,
Steve G0XAR
--
bark less - wag more

Re: KX2: Problem with black enclosure - #QSX ? #qsx

Dave New
 

That's why I drive a brown truck.  It's a 3500 dually (and 21 1/2 feet long), so it doesn't fit in any automatic car washes.  The Quality Research Center at my job (it's a company lease vehicle) has a booth that they can just barely fit it in, so it gets washed every oil change/service, whether it needs it or not.

In the meantime, the brown color hides the dirt better than a black or white truck would.

A light interior helps much with avoiding 'butt burn', especially for vinyl or leather seats.  Accordingly, my interior is known as 'cattle tan/frost', and not the more sinister-looking black-on-black.

The XYL, on the other hand, likes the sinister look in her minivan - the "S" package, which has black-out chrome and badging (there is such a thing, apparently), black alloy wheels, and black interior.  The exterior color is about as close as you can get to MSP (Michigan State Police) Blue.  Not my taste (the color), but it's her car. Smile

73,

-- Dave, N8SBE

-------- Original Message --------
Subject: Re: [QRPLabs] KX2: Problem with black enclosure - #QSX ?
From: "Bob Macklin" <macklinbob@...>
Date: Sun, June 09, 2019 2:07 am
To: "QRPLabs@groups.io" <QRPLabs@groups.io>

Black cars show dirt worse than light colored cars!
 
Bob Macklin
K5MYJ
Seattle, Wa.
"Real Radios Glow In The Dark"

Re: Thermal drift with OCXO update

 

On Tue, Jun 11, 2019 at 09:46 AM, m0bmn wrote:
I am pleased with its performance the worst drift was about 0.5Hz over that time and now back to the point it started, be interesting to see what happens over the day, its not a warm day but it will give me some idea . it looks much better on the QRSS grabbers now and I don’t see any real value in trying to find a sweeter spot on the alignment curve if the drift stays around that amount, I may find a spot with less drift but I don’t think its worth the time to bother for the real world use.
It's all a labour of love really Paul.

Anyone that gets hooked on QRSS and WSPR will eventually become obsessed with stability, hide themselves away in a shed
for a bunch of weekends (just one last test we all say to our XYL's !), before settling upon what is good enough ;-)

At least for a while anyway !

73 de Andy

Re: QCX: 30m Rev 4B Output Power Less than 500 mW #qcx

Andrey (R1CF)
 

Hi Paul,

I am keeping an eye at this thread as the problem you have is very close to what I have with my 5th QCX (17m version).

The main symptom in not the low power (as I am using a driver and a PA it is not a problem). But the Q6 getting hot on key down is the same with your situation. And it doesn’t depend on the output power. I checked everything in the TX part several times, no short connections etc. Replaced Q1-Q3, Q5 – no effect. Everything seems working fine, but the Q6 is beginning to get extremely hot on keying…

Btw, the in my case output power increases when disconnecting the Q5 circuit – is it the same in your case?

Anyway I am interested in what is happening with your QCX. I don`t really know what to do else.

Regards,

Andrey R1CF  

 

From: QRPLabs@groups.io [mailto:QRPLabs@groups.io] On Behalf Of Paul Seger K7AZT
Sent: Sunday, June 02, 2019 1:42 AM
To: QRPLabs@groups.io
Subject: Re: [QRPLabs] QCX: 30m Rev 4B Output Power Less than 500 mW #qcx

 

Again, thanks for the suggestions.

Today I ordered a full complement of capacitors (NPO/C0G), ferrite cores, and transistors to replace the entire output section on the board and to enable breadboarding for the fun of it.  Parts are from Mouser and Amidon to preclude questionable on-line parts.

Thanks for the suggestion to clip leads and to solder to the remaining stubs when replacing.  Yes, I am very concerned about damaging pads.

Testing was performed at 20 MHz, the second harmonic, because I used the QCX as the source and did not want to reinvent the wheel.  Testing at two points is sufficient to tell if the filter is wildly off.  It is too soon to characterize the filter.

73, Paul
K7AZT


Без вирусов. www.avast.ru

Re: QCX: 30m Rev 4B Output Power Less than 500 mW #qcx

Alan G4ZFQ
 

in my case output power increases when disconnecting the Q5 circuit –
Andrey,

Is R64 10K?
Q5 gate zero volts TX?
Did you replace Q5?

73 Alan G4ZFQ

Re: QCX: 30m Rev 4B Output Power Less than 500 mW #qcx

Andrey (R1CF)
 

Hi Alan,
I went to Azerbaijan for a month (business) and can`t check R64 now. Yes, I checked Q5, replaced it just in case and this switch seems working fine.
Q5 gate 0V 100% on TX and it is opened on RX.
...
Andrey

-----Original Message-----
From: QRPLabs@groups.io [mailto:QRPLabs@groups.io] On Behalf Of Alan G4ZFQ
Sent: Wednesday, June 12, 2019 1:03 PM
To: QRPLabs@groups.io
Subject: Re: [QRPLabs] QCX: 30m Rev 4B Output Power Less than 500 mW #qcx

in my case output power increases when disconnecting the Q5
circuit –
Andrey,

Is R64 10K?
Q5 gate zero volts TX?
Did you replace Q5?

73 Alan G4ZFQ




---
Это сообщение проверено на вирусы антивирусом Avast.
https://www.avast.com/antivirus

Re: QCX: 30m Rev 4B Output Power Less than 500 mW #qcx

Alan de G1FXB
 

Hi Audrey,

Sorry, another person called Alan...
there is a saying that too many cooks spoil the broth.
(Too many people adding comments, doesn't help but causes more confusion.)

Just topics to get you thinking if they apply, perhaps read them as general pointers.


Although maybe only recently built, how old and what version PCB do you have?
What was the results of the kit immediately after first power up, has it ever worked to specification?
I recall you have changed many components
Perhaps tell the group which have had no effect, those that made a positive change?

You say Q6 runs hot on keydown.
This device is carrying only the PA current, shaping the leading the following edges.
Perhaps do a firmware reset and start the menu selection afresh with a known starting point in case you have far from logical settings 
The QCX is said to nominally consume 500mA on TX, what is your current draw and what supply voltage?

The QCX17 is the highest band that is available from QRP-Labs.
It will show the greatest variation to component and construction quality.
This is not a criticism of the design or Hans, it's a fact that it gets harder to have repeatable results as frequency increases).

For best results the replacement components need to exhibit the same properties as those that Hans designed the QCX around.
There are past reports where builders have replaced the BS170's for ones sourced by themselves. on more than one occasion this has lead to low output.
In another thread Hans said he recommends Fairchild manufactured devices. You can buy these from his shop if there is any doubt in the ones supplied elsewhere.
(one needs to be sure of manufacture branded devices of full specification, not one just bearing a particular manufactures logo.
There are many successes in purchasing cheaply, the quickest and best chance of success is to purchase from distributors known to supply their components to large business users who would not accept below standard components and quickly flag up supply problems not just to the hobbyist.)

The same applies to Q6, its the only bi-polar transistor supplied. Make sure you have not accidently fitted a BS170
The first 500 kits produced it was a MPS2907, there after it was replaced by a MPS751.
It is not perhaps as a common device as other transistors but it has several properties that suit it's selection well.
If you have replaced this have you used identical device, as substitution requires care?
See http://qrp-labs.com/qcx/qcxfaq.html#mps751 it also flags reports of and solution to PA instability if needed in your case as you say RX coupling Q5 has an effect. http://qrp-labs.com/qcx/qcxmods.html#pa


I do not recall if you have replaced IC3 if so, it is important that this also be of the same specification as Hans calls for.

Beyond that, than perhaps next likely to consider if the LPF has low through loss and the cut off point is correctly tuned.
I hope these are useful pointers.
  regards Alan

u3s autopsy

M0RON
 

Hi,
Last Friday a thunderstorm passed directly overhead and produced three lightning strikes. My U3s was transmitting on 40m wspr at the time into a random wire against a ground network of 8 copper clad steel rods.
At 7pm UK time the u3s was being spotted as normal, the storm passed overhead just after 7. No more spots were made, it should have sent at 7:10pm. 
I checked on the u3s a little later, lcd working, went through a tx cycle and calibrated ok but no spots so I decided to check the output. The u3s lives outside in a brick outhouse powered by a 12v 7ah battery. On picking the u3s up it was noticed that the power leads from the battery had fused together, the +ve lead had melted through to the copper wire in a couple of places but not shorted. I don't have a fuse installed but I do have a 3a diode for polarity protection. 
Put the u3s onto a power meter and output was nil, opened up the case and was met by a pungent smell. Further inspection showed that all three bs170's were damaged, the original supplied one was worst hit. The bias resistor had fused it's body to the first pa transistor, a nearby cap and resistor were scorched and the board badly damaged underneath the first transistor, burnt underneath the other two. 
The first transistor had cracked open and was white, it looks like most of the pa section had been affected. 
Power before it stopped was less than 400mW. Anyway, board is scrap, traces have gone, replacement ordered. 

Andy
--
The universe is made up of Protons, Neutrons, Electrons but contains only one M0RON.

Re: u3s autopsy

SkipF, NT1G
 

You couldn't hear the storm approaching? I keep an am radio tuned to
540 KHz on 24/7.
Sound sorta like looking for a gas leak with a cigarette lighter.
Good Luck!
73 de SkipF, NT1G

On Wed, Jun 12, 2019, 7:22 AM M0RON <eustace.andy@...> wrote:
Hi,
Last Friday a thunderstorm passed directly overhead and produced three lightning strikes. My U3s was transmitting on 40m wspr at the time into a random wire against a ground network of 8 copper clad steel rods.
At 7pm UK time the u3s was being spotted as normal, the storm passed overhead just after 7. No more spots were made, it should have sent at 7:10pm. 
I checked on the u3s a little later, lcd working, went through a tx cycle and calibrated ok but no spots so I decided to check the output. The u3s lives outside in a brick outhouse powered by a 12v 7ah battery. On picking the u3s up it was noticed that the power leads from the battery had fused together, the +ve lead had melted through to the copper wire in a couple of places but not shorted. I don't have a fuse installed but I do have a 3a diode for polarity protection. 
Put the u3s onto a power meter and output was nil, opened up the case and was met by a pungent smell. Further inspection showed that all three bs170's were damaged, the original supplied one was worst hit. The bias resistor had fused it's body to the first pa transistor, a nearby cap and resistor were scorched and the board badly damaged underneath the first transistor, burnt underneath the other two. 
The first transistor had cracked open and was white, it looks like most of the pa section had been affected. 
Power before it stopped was less than 400mW. Anyway, board is scrap, traces have gone, replacement ordered. 

Andy
--
The universe is made up of Protons, Neutrons, Electrons but contains only one M0RON.

Re: u3s autopsy

Alan G4ZFQ
 

Anyway, board is scrap, traces have gone, replacement ordered.
Andy,

Does not look that bad, I would try a repair. But I'm the type that never throws anything out.
I'd suggest the next one has a fuse.
What might have happened is that a high voltage induced from a discharge caused a BS170 to short. No fuse did the rest.
Possibly...

73 Alan G4ZFQ

Re: u3s autopsy

John Canfield
 

I think that's just a simple board with traces on each side, like Alan recommended I would try a repair. Clean up the traces with a Fiberglass scratch pen brush and replace the traces with wire. If a through-hole is smoked it might take some ingenuity for repair. Repair would be faster than building a new U3S.

Sometimes I'll shut down my U3S with an approaching storm and sometimes not. My 132' long end fed dipole lives in the trees so maybe that helps it hide from lightning LOL.

--
John, WB5THT

Re: ENAMEL REMOVAL

Braden Glett
 

How'd you know I only have one working eye?

Re: u3s autopsy

SkipF, NT1G
 

Good thing trees DON'T get HIT by lightning.
(Holding up my SARCASM sign)

On Wed, Jun 12, 2019, 8:49 AM John Canfield <bucket@...> wrote:
I think that's just a simple board with traces on each side, like Alan recommended I would try a repair. Clean up the traces with a Fiberglass scratch pen brush and replace the traces with wire. If a through-hole is smoked it might take some ingenuity for repair. Repair would be faster than building a new U3S.

Sometimes I'll shut down my U3S with an approaching storm and sometimes not. My 132' long end fed dipole lives in the trees so maybe that helps it hide from lightning LOL.

--
John, WB5THT

Just received my clock kit enclosure, I'm having a little trouble reading the newspaper it was wrapped in 😜

K2DB Paul Mackanos
 

one GPS and 2 U3S's

m0bmn
 

 

Hi All

 

Can I ‘share’ One QRPLabs GPS with two side by side u3S’s

Any issues I need to think about?

Thanks guys.

73

Paul M0BMN

 

Sent from Mail for Windows 10

 


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Re: one GPS and 2 U3S's

SkipF, NT1G
 

Can't see why not. Four lines...pwr, gnd, data out and 1 pps. GPS board is
'free running'. Doesn't need any commands.
Best wishes (didn't want to say GOOD LUCK...)
de Skip Flem, NT1G

On Wed, Jun 12, 2019, 3:33 PM m0bmn via Groups.Io <m0bmn=yahoo.co.uk@groups.io> wrote:

 

Hi All

 

Can I ‘share’ One QRPLabs GPS with two side by side u3S’s

Any issues I need to think about?

Thanks guys.

73

Paul M0BMN

 

Sent from Mail for Windows 10

 


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Re: one GPS and 2 U3S's

Bruce K1FFX
 

Have look at:

https://groups.io/g/QRPLabs/message/11820

Hans' answer at the time was "yes".

Best -

Bruce K1FFX

Re: u3s autopsy

Nels Nelsen <nels.nelsen@...>
 

When you say
 "it lives in a brick outhouse"
 that translates to an outdoor 
Bathroom in this part of the country, (across the pond and over the hills).
 Do you also have an indoor loo from a bathroom upgrade or do you just dress warm in the winter?

Just wondering,

NE7LS

On Wed, Jun 12, 2019, 4:22 AM M0RON <eustace.andy@...> wrote:
Hi,
Last Friday a thunderstorm passed directly overhead and produced three lightning strikes. My U3s was transmitting on 40m wspr at the time into a random wire against a ground network of 8 copper clad steel rods.
At 7pm UK time the u3s was being spotted as normal, the storm passed overhead just after 7. No more spots were made, it should have sent at 7:10pm. 
I checked on the u3s a little later, lcd working, went through a tx cycle and calibrated ok but no spots so I decided to check the output. The u3s lives outside in a brick outhouse powered by a 12v 7ah battery. On picking the u3s up it was noticed that the power leads from the battery had fused together, the +ve lead had melted through to the copper wire in a couple of places but not shorted. I don't have a fuse installed but I do have a 3a diode for polarity protection. 
Put the u3s onto a power meter and output was nil, opened up the case and was met by a pungent smell. Further inspection showed that all three bs170's were damaged, the original supplied one was worst hit. The bias resistor had fused it's body to the first pa transistor, a nearby cap and resistor were scorched and the board badly damaged underneath the first transistor, burnt underneath the other two. 
The first transistor had cracked open and was white, it looks like most of the pa section had been affected. 
Power before it stopped was less than 400mW. Anyway, board is scrap, traces have gone, replacement ordered. 

Andy
--
The universe is made up of Protons, Neutrons, Electrons but contains only one M0RON.

Re: u3s autopsy

Russ@va3rr
 

An outhouse is a shed...