Date   

Re: BPF trimmer sensitive to screwdrivier touch?

Jess Gypin <ontarget1911@...>
 

I’ve used them all. Metal screw driver, just stick it in there, make a tweak and then pull it out to see what happens. What’s the big deal brain damage?

On Mar 17, 2018, at 5:07 PM, David Wilcox via Groups.Io <Djwilcox01=yahoo.com@groups.io> wrote:

I use ceramic screw drivers to adjust any tuned circuit part. The metal screw driver will change the frequency by detuning the coil or trimmer cap. There are some plastic tuning wands a available too but I like my ceramic set. Just look for ceramic screw drivers at Amazon. $10 to $14 a set.

Dave K8WPE

On Mar 17, 2018, at 4:39 PM, g3xaq <alan@g3xaq.net> wrote:

I did notice one thing during alignment: when peaking the receiver BPF trimmer the level changes (and I get noise on the audio) when I apply a metal screwdriver to the trimmer. Is this expected? I've checked and I do have the trimmer inserted the right way round: it is aligned with the silk screened component overlay.

Before I go in gung-ho with a soldering iron and risk damaging the trimmer and/or PCB, is this expected behaviour or not?

73, Alan G3XAQ





Re: Hans, please weigh in on suggested fixes or improvements #qcx

Steve
 

This is a good question.

 

I've built 3 QCXs and all of them had a slow decay in semi break-in mode. Changing R41 to 220 ohms fixed that on all of them.

 

All 3 also had a thump in the sidetone. Changing C22 to 0.1uf fixed that on all 3, and made the sidetone sound sweet.

 

I'm not complaining because I love this little radio. Making changes and tweaking things is a big part of the fun for me. 😀

 

Maybe Hans has a reason for not endorsing these changes, but if one uses them it's much easier to do while building the kit because it's a bit of a PIA to unsolder parts and/or acquire more parts if one doesn't have them.

 

Steve, N4IAG


Re: U3S doesn't always sync time on startup

N1BUG
 

Next time it happens I will try that. The trick with me is
remembering to watch out for it since this only happens occasionally
and I am easily distracted.

73,
Paul

On 03/17/2018 06:59 PM, Al Holt wrote:
What you've describes sounds like what my U3S does; I have the same
issue. I'm in the habit now of after powering up the unit, press the
left button and step through the whole menu system, press right
button to get back normal operation. 

The U3S now goes into a calibration routine and will have the right
time at the end of the sequence. I'm on the current firmware.

--Al
WD4AH


Re: BPF trimmer sensitive to screwdrivier touch?

David Wilcox K8WPE
 

I use ceramic screw drivers to adjust any tuned circuit part. The metal screw driver will change the frequency by detuning the coil or trimmer cap. There are some plastic tuning wands a available too but I like my ceramic set. Just look for ceramic screw drivers at Amazon. $10 to $14 a set.

Dave K8WPE

On Mar 17, 2018, at 4:39 PM, g3xaq <alan@g3xaq.net> wrote:

I did notice one thing during alignment: when peaking the receiver BPF trimmer the level changes (and I get noise on the audio) when I apply a metal screwdriver to the trimmer. Is this expected? I've checked and I do have the trimmer inserted the right way round: it is aligned with the silk screened component overlay.

Before I go in gung-ho with a soldering iron and risk damaging the trimmer and/or PCB, is this expected behaviour or not?

73, Alan G3XAQ



Re: U3S doesn't always sync time on startup

Al Holt
 

What you've describes sounds like what my U3S does; I have the same issue. I'm in the habit now of after powering up the unit, press the left button and step through the whole menu system, press right button to get back normal operation. 

The U3S now goes into a calibration routine and will have the right time at the end of the sequence. I'm on the current firmware.

--Al
WD4AH


U3S doesn't always sync time on startup

N1BUG
 

Hi,

I am just wondering if others have seen this or whether I should be
looking for a problem in my U3S/QLG1. Most of the time when I switch
it on, it syncs time within 20 to 50 seconds. Occasionally it fails
to sync time even though the GPS status message says it has acquired
satellites and has a fix. Correct coordinates are being shown. In
all such cases, powering the unit off, then on again causes an
immediate time sync.

The U3S is running firmware v. 3.12. I have the QLG1 mounted in the
QRP Labs case with the U3S, using an external active antenna mounted
on a metal cabinet. GPS signal strength looks good and it always
acquires satellites.

73,
Paul N1BUG


Re: QCX CW Beaconing #qcx

Al Holt
 

John,
Thanks for your helpful suggestions. I had a bit of a go with QRSS during the QRSS New Year's festival (I think it was). My U3S really didn't cut the mustard as far as stability went and my plans to reconfigure it are on the shelf for now. I do a lot of WSPR transmitting and just looking to get more time on the QCX. I've burned out one set of finals and taken some measures to prevent it happening again. 

But yes, I could set up shop just at the bottom of 40m QRSS-land, say 7,039,703 Hz, and send some ID-Grid-73's, right?

Thanks!!

--Al


Hans, please weigh in on suggested fixes or improvements #qcx

Steven Dick
 

There are several posts out there on suggested improvements that have not been commented on or officially sanctioned by the designer.  These include:
1. suggested fix for the "thump" (I.E. reduce value of C22 from 10uF to 0.1uF)
2. Various issues relating to the Q6 shaping circuit (I.E. change resistor values for reliable turn-on and/or partial RF output when not turning fully off in semi-QSK issue.

Some of the recommended changes appear to have merit but I am reluctant to change anything without official comments by the designer and added to the .QCX modifications page.

Thanks,
Steve K1RF


Re: BPF trimmer sensitive to screwdrivier touch?

Alan G3XAQ
 

Yes, John, that's what I did. One side of the trimmer is grounded but it looks like the PCB layout has it the wrong way round? No big deal. I just wanted to be sure I didn't have a fault.

I have a dreadful thump on the sidetone and on semi-QSK there is a low level RF output during the "hang" time. I seem to remember seeing both these faults discussed on here so it's time to try out the groups.io search function...

73, Alan G3XAQ

On Sat, Mar 17, 2018 at 02:18 pm, John Pagett wrote:


Alan,

You should use an trimming tool which is either fully insulated (hard plastic)
or where the small blade is the only metallic part. In emergencies I've filed
up a plastic knitting needle to make a trimming tool (don't tell the XYL!)

73
John
G4YTJ
On 17 Mar 2018, at 20:39, g3xaq <alan@g3xaq.net> wrote:

I did notice one thing during alignment: when peaking the receiver BPF
trimmer the level changes (and I get noise on the audio) when I apply a metal
screwdriver to the trimmer. Is this expected? I've checked and I do have the
trimmer inserted the right way round: it is aligned with the silk screened
component overlay.

Before I go in gung-ho with a soldering iron and risk damaging the trimmer
and/or PCB, is this expected behaviour or not?

73, Alan G3XAQ



Re: BPF trimmer sensitive to screwdrivier touch?

Denis F6GKQ
 

As John wrote above, use a special trimmer tool.
Never trim an RF circuit using a metallic screwdriver.
Use alignment tools, see attached picture.

--
73 from Denis, F6GKQ
QCX 40m nr 3082


Re: BPF trimmer sensitive to screwdrivier touch?

John Pagett G4YTJ
 

Alan,

You should use an trimming tool which is either fully insulated (hard plastic) or where the small blade is the only metallic part. In emergencies I've filed up a plastic knitting needle to make a trimming tool (don't tell the XYL!)

73
John
G4YTJ

On 17 Mar 2018, at 20:39, g3xaq <alan@g3xaq.net> wrote:

I did notice one thing during alignment: when peaking the receiver BPF trimmer the level changes (and I get noise on the audio) when I apply a metal screwdriver to the trimmer. Is this expected? I've checked and I do have the trimmer inserted the right way round: it is aligned with the silk screened component overlay.

Before I go in gung-ho with a soldering iron and risk damaging the trimmer and/or PCB, is this expected behaviour or not?

73, Alan G3XAQ



Re: QCX CW Beaconing #qcx

John Kirby
 


More info...

QRSS and WSPR freqs
http://www.g6nhu.co.uk/frequencies.html

John
N3AAZ


Re: A word about QRP Labs capacitors and toroids

Steve
 

On Wed, Mar 14, 2018 at 04:18 am, Adrian Scripcă wrote:
I just replaced C25 and C26 with some polystyrene capacitors (I didn't have NPOs for these values) and the output power went up nicely, in accordance with the specified numbers.

I think Adrian may be on to something.  I had already removed windings on L1, L2 & L3 to get maximum power out on my 30m QCX, but after replacing C25 & C26 with polystyrene caps (same value), my power went from 2W to 3W on 12v, for a nice 50% increase.

 

It appears that the stock caps are a bottleneck on 30m, and likely the other higher bands. 

 

Steve, N4IAG


Re: BPF trimmer sensitive to screwdrivier touch?

Roger Hill
 

I get the same thing with the standalone receiver module.

Roger
G3YTN

---
***************************
Roger Hill
***************************

On 2018-03-17 20:39, g3xaq wrote:
I did notice one thing during alignment: when peaking the receiver BPF
trimmer the level changes (and I get noise on the audio) when I apply
a metal screwdriver to the trimmer. Is this expected? I've checked and
I do have the trimmer inserted the right way round: it is aligned with
the silk screened component overlay.
Before I go in gung-ho with a soldering iron and risk damaging the
trimmer and/or PCB, is this expected behaviour or not?
73, Alan G3XAQ


BPF trimmer sensitive to screwdrivier touch?

Alan G3XAQ
 

I did notice one thing during alignment: when peaking the receiver BPF trimmer the level changes (and I get noise on the audio) when I apply a metal screwdriver to the trimmer. Is this expected? I've checked and I do have the trimmer inserted the right way round: it is aligned with the silk screened component overlay.

Before I go in gung-ho with a soldering iron and risk damaging the trimmer and/or PCB, is this expected behaviour or not?

73, Alan G3XAQ


QCX 20M serial 3647 is alive!

Alan G3XAQ
 

I just finished assembling my QCX. I've had it the best part of a week so I'll not be winning any prizes for speed of construction. I did replace the suspect 390pF capacitors in the LPF with Murata SMD types. Anyway, big sigh of relief, it worked on power up with no obvious faults. It hears down to about -125dBm and produces 3W output from a 13.8V DC supply. The second harmonic is -54dBc. I believe some builders see 3.5W and hear -130dBm but I am happy enough with my results.

Thanks for a great kit, Hans.

73, Alan G3XAQ


Re: Sudden failure in early life

Glen Leinweber
 

Steve,
Your I2C transaction looks to be corrupted.
I have transformed your 'scope image (below).
SDA should rise between transactions. It doesn't.
"ACK" looks to come in the middle of a transaction (should come at the end.

Am guessing a power-up problem. Perhaps a slow rise in the DC supply?
In any case, looks like SI5351A sees a I2C framing error.


Re: Sudden failure in early life

George Privett
 

My QCX-20 worked well when completed. However, when I took the LED off and put it back on several times when looking at options for a case, it started to display random characters.  Upon close examination, I found that one of the pins in the header had a cold solder connection. A bit of resin and solder fixed it quickly and I have not had a problem since. This is an amazing radio kit. Kudos to Hans. The instructions are some of the best and I felt like Hans was right there as an elmer looking over my shoulder, while I assembled the radio.

George VY1GP


Re: QCX CW Beaconing #qcx

John Kirby
 

p.s.
QRSS can be CW at various speed or other modes such as FSK
JOHN


Re: QCX CW Beaconing #qcx

John Kirby
 

AL,

The QCX 5 is a big time fun radio, lots of options (TNX G0UPL)

Definitely read regs with respect to 24/7  unattended operation

QRSS freqs, there is a qrss group here on 'groups.lo'
WSPR freqs, spots and chat group, ceck out wsprnet.org

wspr decode download (TNX K1JT)
 http://www.physics.princeton.edu/pulsar/k1jt/wsjtx.html

re wspr and the qcx, WWV and menu 8.6 must be within +/- three seconds or better

check out ARGO, down a copy free big time fun (TNX I2PHD)

re CW done be shy...why?
QCX will decode CW for QSO helper :>)

72 73
John
N3AAZ