Date   

Re: [help] Only noise being seen while IQ balance / phase lo / phase hi.

Jose Tent
 

Thank you Don.  I believe I have formed an attachment to it now.   And...I still don't understand every thing, but I understand a great deal more.  

I'm really looking forward to the QSX comming out.   If the level of quality, innovation and low price stays the same as QCX, it's gonna be great !  I'm also tempted to buy the new QCX+ and building a 20m version as well....

Thanks again all. 


Re: What to do with High Fuse set to 0xD9 #qcx

Bill NF6R
 

And again, Thanks Alan!

I just put 1.05 on a friend's QCX20 Rev3.

73,
--

Bill - NF6R
SKCC 20696 NAQCC 9984 FISTS 19479 CalQRP 78 Flying Pigs 4181


Re: TCXO for U3S CPU clock #u3s #clock

HF
 

Hi Razvan,
Thanks for shooing me away from changing the CPU clock frequency.  I do like WSPR. Alan just encouraged me to try putting the 27 MHz TCXO signal right into the CLK1 input.  That should keep my timing correct for at least a few weeks at a time.
A TCXO enabled me to make U3S WSPR work on 2 metres.  I'd like to see if I can push it up to 220 MHz.  I'd like to go higher, but that will require different hardware, as the U3S can't shake any faster than 230 million times per second.
I considered using a DDS like the one in the U3S to obtain a 10.24 MHz reference oscillator for my IC-271H.  But one has to tell the DDS what frequency to go to every time it turns on; that means I'd have to put a microcontroller in there, too.  Too complicated.  With some research, I found a 1-chip solution.  The frequency conversion uses a field-programmable PLL IC from Cypress.  Here's an article that describes how that works starting with the same type of 20 MHz TCXO I put in my U3S for the synthesizer reference.

https://groups.io/g/icomclassic/files/IC-271H,%20IC-471H/TCXO%20for%20IC-271H%20summary%20v2.pdf

Phase noise from this conversion might matter in this application whereas it didn't seem to matter on the -271H. 
Here are 2 articles about using the TCXO I found that's even more stable than the one I used for the IC-271H.  In this case, I didn't need to convert the frequency because the stock TCXO had the exact reference frequency I needed.

https://kenwood-hybrids.groups.io/g/main/files/TS-830S%20stability%20and%20accuracy%20improvement%20modifications

My experience with this TCXO was less than 0.5 Hz drift as the TS-830S and VFO-230 warmed up from 13C to a few degrees above ambient in a room at 20 C.  That's much better than the 20 MHz TCXO I had used before.
The next project might be to use this 10 MHz TCXO and the PLL chip to make a 10.24 MHz reference oscillator for the IC-471H.  Up there, the stability improvement would probably be noticeable.
You're mostly right about the unobtanium - the only place I know of to get the programming dongle for these is on the shelf in my radio room.  They show up on ebay from time to time.  I'm not aware of anyone else looking for them though.  At least one other company offers a similar product - their version might be readily available though more expensive.
There is yet another potential solution that doesn't involve receiving a GPS signal from time to time.  One can get a rubidium oscillator.  Then, either change its programming to give the frequency you want, or use it as the input to a field-programmable PLL.  That should drift less than any TCXO!  .
Cheers
Halden VE7UTS


Re: Strange Transmit Characteristic

 

If something really simple is all you need, the QRPGuys SWR indicator might fit the bill:
https://qrpguys.com/tuning-indicator
It's the same circuit that's in their antenna tuner (that I have), it's designed for QRP, and at $20 it does the job at a decent price. By very nature of the resistance bridge circuit it guarantees a max SWR of 4:1, so taking out your finals is difficult.
It won't give you a numerical value, of course, but it tells you what you need to know.
Of course, if you need a tuner, the combined version works well too.
--
Julian, N4JO.


Re: Strange Transmit Characteristic

wfcaston@...
 

I do not yet have a QRP method of measuring SWR but I am going to buy a unit to do that.
--
Anson
WV4C


Re: Strange Transmit Characteristic

N3MNT
 

Hook up a good dummy load and try the same thing.  If you have a high swr the finals will heat up and could be damaged.


Re: Strange Transmit Characteristic

 

I'm going to throw out a wild guess that heating at the display means heating at the finals, and coupled with no returns you may easily have an antenna problem - at least high SWR. Be careful with those little finals, they're not very robust.
Do you have something to check SWR with ??
--
Julian, N4JO.


Re: Questions about QSX radio (by QRP Labs)

geoff M0ORE
 

Just to echo Allison's comments, an earth on the top floor of a block of apartments is useless at RF. An amateur local to me ( he celebrated his 100th birthday during the lockdown) lives in the penthouse suite of a block of flats overlooking the English Channel and it just happens to be a quarter wave at 80m above ground level. This means that even if he ran an earth wire directly down from his radio room to the ground, being a quarter wave would be a very high impedance. He did try an upside down quarter wave vertical just for the fun of trying it but too much noise from other flats. He now relies on trap dipoles and a loop aerial on 80m.

On 04/06/2020 17:16, ajparent1/KB1GMX wrote:
On Thu, Jun 4, 2020 at 08:04 AM, <makkiato@...> wrote:

- I live in an apartment (top floor). 

Height is always helpful.

- I need to be discrete (no vertical antennas), but potentially (better to avoid but) I can try to spread an horizontal antenna (max 10meters long) outsides the windows of one of the sides of my flat.

10M long is right for a 20M band Dipole antenna.  Also 20M is a good DXband.

- I have no good "ground" to connect to. I could use the building's mains ground, but I don't think that's a particular good one to connect to (?!?)

Adequate for the task Electrical safety.  For a dipole antenna "ground" is 
not required save for lightning.

Given these constraints I have identified two interesting option:

1) A "portable/car" monoband antenna, like the Diamond HF20FX. It has good reviews (https://www.eham.net/reviews/view-product?id=8060) but I don't know if it needs a ground?!?

IT requires a ground normally the metal body of the auto supplies that.

Also its electrically short, any time you make an antenna shorter with coils it will
be less efficient.

2) An half-wave horizontal dipole for max 20m (i.e., max 5m + 5m = 10m in total), to be placed horizontally. Is this a good idea? Can you suggest one?

I see the https://mfjenterprises.com/products/mfj-2220?_pos=3&_sid=bb33b0635&_ss=r , would that be good?

It can work if high enough (above building) but that is just two mobile whips back to back and not terribly efficient.

Typical dipole for 20M is about 10M long (33.6 feet give or take)  fed in the middle with coax.  Easily made and 
generally works well.

IF your receive only all this is less critical.  For transmitting your antenna is important for best
possible result.  That is especially true at low power having less to waste.

Allison
-------------------------------
Please reply on list so we can share.
No private email, it goes to a bit bucket due address harvesting


Re: Strange Transmit Characteristic

wfcaston@...
 

Lee and Julian:

Thanks for the replies.  Yes, the problem went away when I changed the setting to full break-in!  I think the signal I heard was actually going out on the air.  Now the signal going out was pretty clean.  I noticed when I called CQ for an extended period of time, (no replies yet) the unit heated up quite a bit at the display.  Should I limit the number of CQs so as not to heat the unit, or would you think the QCX is robust with respect to duty cycle?

You guys are helping me not to get frustrated.  Next thing I need to do is get a really high 1/2 wave dipole up in the air.

73 all,
--
Anson
WV4C


Re: Strange Transmit Characteristic

 

Thanks for that, Allison. I don't have any kit other than my QCXs, so I wouldn't have known that gem of information :-)

I do have a little QRP-Guys multi-tune tuner, with an LED indicator which, in tuning mode, glows with increasing SWR. I can clearly see the pulsing of dits on my QCX, and so could easily spot a keyshaper issue.

You don't happen to have such a handy indicator of Tx power, do you, Anson? Alternatively, what does it sound like in full QSK mode? Do you hear the breaks in the QCX receiver then? If you do, then Allison's answer may be spot on (it probably is :-) )
--
Julian, N4JO.


Re: Strange Transmit Characteristic

ajparent1/KB1GMX
 

IT would he hard to tell!

The station rx will easily hear the nearly 5-10mW of the Si5153 under all conditions.
You may hear it at a distance.

Its possible there is keying issues but even if its correct you can hear the "blow by"
as its in the milliwatt or more range.  I have one!

Allison
-------------------------------
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No private email, it goes to a bit bucket due address harvesting


Re: Strange Transmit Characteristic

 

Allison,
I was inferring from his description that the envelope shape was long, so one pulse blended with the next, but that it did decay. Maybe that last part is incorrect.
If that were the issue, what would be the difference in what you'd hear on an adjacent receiver?
--
Julian, N4JO.


Re: Strange Transmit Characteristic

ajparent1/KB1GMX
 

>>When I set the automated CQ and listened with my Icom 737 in the shack, the automated CQ message ran together.  it sounded like there was a carrier and no silence between dits and dahs. <<

That is because the VFO (SI5351 runs all the time and the radio next to it can hear the signal.
ON RX, the SI5351 is also running for RX, your station receiver will hear that too.
It is NORMAL.  THe question has been raised many times before.

Weak receive maybe because the radio is not dialed in (check instructions).

Allison
-------------------------------
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Re: Strange Transmit Characteristic

Lee
 

Anson, are you using semi break-in?  If you are, switch to full break-in.  You may be hearing backwave which is not actually transmitted.
 
73 de WA3FIY  Lee
 
 

------ Original Message ------
Sent: 6/4/2020 5:02:38 PM
Subject: [QRPLabs] Strange Transmit Characteristic
 
Background information: 
Ver. 1.00G 2019  
The qcx was built by another ham from whom I bought it.
I have only had it for several weeks.
It is attached to a QRP trapped dipole which I constructed for portable use and is only a few feet above the ground.
I keep the unit connected to an antenna or dummy load when transmitting.
It receives signals ok, but not too loudly.   
I have not yet made a qso.
I am now connected to a much better power, Astrton 20 amp power supply.  
***************************************************************************************

Problem:
When I set the automated CQ and listened with my Icom 737 in the shack, the automated CQ message ran together.  it sounded like there was a carrier and no silence between dits and dahs.  I then set the keyer for straight key.  I then tried to send a stacato dit, as short as possible, and there was about a 3/10 second character minimum transmit time.  In other words, that is a minimum time that the unit can transmit, and that time is way too long.  What could be causing this unit to maintain the signal so long, even with a really short key down time?  Maybe a setting?
--   
Anson
WV4C


Re: Strange Transmit Characteristic

 

Further thoughts:
Note that in order to test this you'll have to remove the display (with power off, of course!) but you can operate the device without it as long as you set up the keyer modes and save the configuration first.
--
Julian, N4JO.


Re: Strange Transmit Characteristic

 

Sounds like it might be a problem with the key shaper circuit comprising Q4, Q6, R41, R42, C31, C32. Perhaps check those valves are correct?

--
Julian, N4JO.


Strange Transmit Characteristic

wfcaston@...
 

Background information: 
Ver. 1.00G 2019  
The qcx was built by another ham from whom I bought it.
I have only had it for several weeks.
It is attached to a QRP trapped dipole which I constructed for portable use and is only a few feet above the ground.
I keep the unit connected to an antenna or dummy load when transmitting.
It receives signals ok, but not too loudly.   
I have not yet made a qso.
I am now connected to a much better power, Astrton 20 amp power supply.  
***************************************************************************************

Problem:
When I set the automated CQ and listened with my Icom 737 in the shack, the automated CQ message ran together.  it sounded like there was a carrier and no silence between dits and dahs.  I then set the keyer for straight key.  I then tried to send a stacato dit, as short as possible, and there was about a 3/10 second character minimum transmit time.  In other words, that is a minimum time that the unit can transmit, and that time is way too long.  What could be causing this unit to maintain the signal so long, even with a really short key down time?  Maybe a setting?
--   
Anson
WV4C


Re: How about an ultra-portable "QCX mini" version? #qcx

 

Thanks for that correction, Shirley; I'm totally cool with being fact-checked ;-) (... and thanks also for the additional info).
Arduino dropped it for a little while a couple of years ago - a lot of work in keeping it all transparent, apparently - but then brought it back, presumably by heavy demand.

I like using the Due, and have a pair of them on my desk at this very moment, interconnected, in a project for my work.

I also use the Mega2560 a fair bit, too, as though it isn't any faster than the 328, it has - as the other posters have said - a lot more memory and IO. My son was using one just recently in conjunction with a vanilla Uno for his senior project for his EE degree.

There are some differences between the AVR... dealing with data sizes like words, ints, and floating points, and of course anything hardware register related like interrupts and analog output: Due has two real DACs so they don't need to synth an analog output with PWM. On the whole, and to agree with you, I think they've done a spectacular job in making their utilization as transparent as possible.

Anyway, back to work ...
--
Julian, N4JO.


Re: TCXO for U3S CPU clock #u3s #clock

DL2ARL
 

Hello Halden VE7UTS, hello group,
I have had a similar discussion some years ago, interested in using a commercialy available 10MHz TCXO instead of the 27MHz for the U3S. Hans has very kindly answered all my questions, but I was too shy to ask more, so my understanding is only half of what he was trying to tell me. I finaly gave it up an bought a TCXO from qrp-labs and now I am in the prospect of gaining a yet better version also from qrp-labs custom made for the brand new qcx+ but working with other rigs too (if wired in).

This is what I understood at that time from the discussion: if you would NOT care about WSPR, only being interested in traditional modes and qrss, nothing would speak against using a TCXO with another frequency, whatever this frequency might be. But for the computation of the WSPR Tx, the only feasible TCXO frequencies would be 27 and (maybe) 25MHz, especially on 2m for some reason. I think, if you would search after my callsign and+and the one from Hans on this group you might have the chance to find the original conversation and understand more than I did. Or wait until Hans finds time to answer this question again. The search function is ante-deluvial on this forum.

Regarding your message above:
"I have come across an inexpensive but extremely stable 10 MHz TCXO and a circuit that can convert that signal to 27 MHz"

I suspect this must be some kind of miracle gadget built of that unobtainium stuff everybody looks for nowadays. I have no idea how one could convert 10 to 27 MHz, but would be very eager to learn how. On the contrary, making 10MHz to say 20 or 30MHz (or even to 25) should be a breeze, but not to an odd frequency like 27 without mixing it with something containing a "7" and thus sacrificing the temperature compensation of the 10MHz clock and getting a forest-full of cross-modulations.

Tell me more about that!
yours friendly, Razvan DL2ARL


Re: 6 Band U3S Revisisted

Curt M.
 

I thought these came from Digikey but after the part numbers not bringing anything up on their site, I noticed on the bags that they came from Newark.  If I remember correctly the issue was only with one of these parts but I changed them both out.  You'll need two for each 20m filter if you haven't looked at that for a while.

The 180pf cap is:
https://www.newark.com/multicomp/mc0805n181j500a2-54mm/ceramic-capacitor-180pf-50v-c0g/dp/46P6440 

The 390pf cap is:
https://www.newark.com/multicomp/mc0805n391j500a2-54mm/ceramic-capacitor-390pf-50v-c0g/dp/46P6551?ost=MC0805N391J500A2.54MM