Date   

Re: #wspr U3S for 2m WSPR: How to remove the frequency-swing at start of transmission #wspr

Alan G4ZFQ
 

Changed to basic crystal reference.

I show my RX at ~27.005MHz of the crystal frequency with Park mode 3 at the end of one TX/beginning of another. And two using Park mode 0, one at the start after idle, one between two transmissions.
"Start of TX from Parkmode3" shows a small section of the cyclic movement on 2m.

The initial jump at the start of the transmission is quite fast, probably what Henning sees on 2m.
Personally I do not think the initial rapid frequency shift is of any real consequence for WSPR.
After another hour or so 1032 13 -0.5 144.490529 2 G4ZFQ IO90 0 a drift of 2Hz, not yet as good as Henning but not too bad.
And 1042 13 -0.8 144.490540 0 G4ZFQ IO90 0 Zero drift.
But after that it began to drift again, temperature? Not really, more a slow cyclic drift. Removed Synth module LM317, fitted low drop 3V3 regulator AMS1117, an Ebay module. No difference.
I am thinking this is not entirely a heat-related problem, switching inside the Si5351 as the frequency is changed alters the capacitive loading on the 27MHz crystal? The cyclic drift could be associated with the pattern of WSPR tones.
Now in another thread Hans reminds me that there are no loading capacitors on the crystal (apart from those inside the Si5351 which are lower than specified) Is the crystal therefore more sensitive to loading?
So, in goes my Adafruit module with a 25MHz SM crystal.
This is looking promising. Even though 25MHz means the WSPR frequency shift is compromised it is decoding reliably on 2m with drift 2 or 3Hz. Any fluctuation due to WSPR frequency changes was not obvious.
Now back to the basic 27MHz crystal Synth, put in two 15pF loading capacitors, hoping that would overwhelm the cause of the "modulation" of the 27MHz. It started almost dead on 27MHz, drifting down, settling about 60Hz down. But this was far worse, the 27MHz was not stable even when the U3S was idle.
That is about as far as I can go the Adafruit shows a simple crystal can work on 2m but my Synth board does not.
It is better to use a TCXO and, presumably, the QRP Labs OCXO.

(This is a U3S run with one BS170 and ~5V on the drain so not much heat generated. I have it in a custom box with the display on top, the synth module therefore at the bottom.)

Maybe Park mode needs to be considered carefully? Mode 0 gives an output, my observations see less than 30dB below the WSPR signal level at 144MHz. A setting of 150MHz works OK but if my figure is correct a signal will go out.

> You wonder about the source of 50 Hz sidebands. May I posit a cause?....

Glen,

Thanks for your thoughts. It is OT if my observations are of locally created spurii but I thought I should mention it so others may check.
I still observe spurii on HF with a different RX system all 50Hz apart, worst -44dB on 10m.
2m not noticed this time, in fact seems fairly clean. Strange, possibly just my test method.

73 Alan G4ZFQ


Re: U3S Case front panel push buttons

Alan de G1FXB
 

To prevent excess heat reaching the switch body, clamp a haemostat* between the switch and the tag.
*A pair of needle nose or pointed pliers held shut with an elastic band is a good substitute.

Alan

On 06/12/2018 17:02, Curt M. wrote:
I'm sure there's probably something else out there but it seems like the key with those switches is not put too much heat on the terminals when you solder the wires in place.  They seem to act very similar to relay contacts when you put too much current across them.  We used to always say that the contacts were "gulled", not sure if that is the correct spelling or even the correct term but that's what we used to say where I worked a number of years ago.

When I solder those terminals I quickly push and release the button multiple times as soon and I pull the soldering iron tip away.  There were times a while back that the button would stick on the in position and it was from too much heat.  Now they seem to hold up better with a lighter touch with iron but those switches are not good quality right out of the gate so I know what you are saying.


Re: No GPS data with U3S - For Hans

Brian Summers
 

I've managed to come up with a procedure for repeating my problem. I've got the unit mode indices programmed so it operates as follows:

1. Power on U3S. Ultimate3S 3.12a appears. Then the display switches to GPS data as it should.

2. Press the Menu button once and the display reads:

0]-0-000,473,000
TX CW-------00-0

3. Press the menu button again and the displays reads:

1]-0-000,473,000
TX CW-------00-0

4. All the above really shows is that I have the same message in mode index 0 and 1. Not intentionally I might add. I'm new to the U3S so this is all happenstance.

5. Now power off/on. Once again the Ultimate3S screen appears followed by GPS data.

6. Press the menu button once and see the display as para 2 above.

7. Now press the edit button twice to enable. The display will show:

0] 0 000,473,000
TX CW       00 0

8. Power off/on. The Ultimate 3S screen appears, the GPS data does not appear and instead the display shows as follows. The beating heart appears where it should.

0] 0 000,473,000
TX CW

9. Press the menu button again and see:

0] 0 000,473,000
TX CW       00 0

10. Press the menu button again and see:

1]-0-000,473,000
TX CW-------00 0

11. You can see from 8 and 9 that I've created two messages identified with mode index 0]. Now you can repeat from para 8. The unit goes directly from the Ultimate 3S screen to the first mode setting every time, bypassing the GPS data screen. It all repeats.

12. To recover from this situation power off/on as para 8, go to the screen shown in para 9, then press the edit button twice to disable the mode setting. Now power off/on and GPS data will follow the Ultimate 3S screen.

Doubtless there are other ways of demonstrating this but the above is repeatable for me. Here's hoping that when I post this the formatting does not change........

Brian VE7JKZ



On 11/30/2018 8:34 AM, Brian Summers wrote:
GM Alan,

For the record my notes show the following when trying to set up for 473Khz.

0] 0 000,473,000 then on the line below, TX CW.  Call this message A

now press the menu key and the display shows:

0] 0 000,473,000 then on the line below, TX CW      00 0.  Call this message B.

Under these conditions there is no GPS data. Now disable message B, switch off/on, then GPS data appears immediately following the Ultimate 3S information screen.

I suppose I could spend more time on this trying other modes and messages but it can be very time consuming particularly with the case mounted push button switches which I find to be very flimsy and troublesome. For now I'm content to know that if I have no GPS data and scroll the menu to find two messages with the same number, I know what to do about it.

73 Brian VE7JKZ


On 11/30/2018 2:42 AM, Alan G4ZFQ wrote:
Strange thing is, no error message appears.

 Brian,

I guess if Hans knew it would happen there would be no error message because he had put it right!

>when two almost identical modes are set with the same band number

Maybe let Hans know exactly what settings, what are "almost identical" modes?

73 Alan G4ZFQ










Re: QCX CW transceiver

Roland Williams
 

I used clear nail varnish on the two I built and usually do that for anything that’s likely to move; it’s also good for stopping nuts from unscrewing to rattle around without making them impossible to remove. When I install transformers (the eight legged one is a great example) I just cut the wires to different lengths and use tweezers to put them in one at a time. Yes it’s fiddly but patience works fine. 

Roland AE6VL

On Dec 6, 2018, at 2:03 AM, David Wilcox via Groups.Io <Djwilcox01@...> wrote:

Has anyone used any Q Dope or finger nail polish on the ends of the wires on the coil to hold the wires in place to make it easier to insert on the board?  In other kits the wires started to loosen while fiddling with them trying to get them all in the correct holes.

David J. Wilcox K8WPE’s iPad

On Dec 5, 2018, at 2:39 PM, Dave Redfearn <n4elm@...> wrote:

Ken,
I used 32 ga wire for my 80 & 60 Meter QCX builds on the main winding of T1 to get the winding to fit on the core.
I used the supplied wire for the three 5 turn links.

Tune up was normal.
I did have to remove 2 turns from the main T1 winding on the 60 Meter radio to have the capacitor set properly at ~ 3/4 mesh.

73 - Dave, N4ELM


Re: U3S Case front panel push buttons

Curt M.
 

I'm sure there's probably something else out there but it seems like the key with those switches is not put too much heat on the terminals when you solder the wires in place.  They seem to act very similar to relay contacts when you put too much current across them.  We used to always say that the contacts were "gulled", not sure if that is the correct spelling or even the correct term but that's what we used to say where I worked a number of years ago.

When I solder those terminals I quickly push and release the button multiple times as soon and I pull the soldering iron tip away.  There were times a while back that the button would stick on the in position and it was from too much heat.  Now they seem to hold up better with a lighter touch with iron but those switches are not good quality right out of the gate so I know what you are saying.


Re: Active Aerials

ajparent1/KB1GMX
 

John, VA7JBE

No, That's designed for VHF and UP.  it would be terrible for a whip.

The amrad whip was a project maybe 10 years ago and use the CP600 series JFET.
The article is posted with this message.  FYI the fest are still available from teh source listed
as of last year when I ordered some.

For loops I included a copy of Chris Trask's paper, its a very good design.

FYI most MMIC amp including the PGA103 suck at less than VHF.  The coupling caps
are too small, The output choke used is too small a value for HF and the Phemt based
devices used are not very good at HF.

Allison


Re: Active Aerials

Alan de G1FXB
 

Perhaps it's the AMRAD active antenna featured QST Sept 2001 ?

Alan


On 06/12/2018 13:51, Karl Heinz Kremer - K5KHK wrote:
Allison,

do you have a title or an author for the QST article?

On Wed, Dec 5, 2018 at 01:10 PM, ajparent1/KB1GMX wrote:
AMSAT active antenna

 
--
Karl Heinz - K5KHK


Re: Active Aerials

Karl Heinz Kremer - K5KHK
 

Allison,

do you have a title or an author for the QST article?


On Wed, Dec 5, 2018 at 01:10 PM, ajparent1/KB1GMX wrote:
AMSAT active antenna

 
--
Karl Heinz - K5KHK


Re: Active Aerials

Graham, VE3GTC
 

Try the PGA-103 MMIC (Mini-Circuits brand).

while not targeted for MF/HF use it does work remarkably well at that
frequency range.

VHF and up oriented but a good all round intro to the device:

http://www.w1ghz.org/small_proj/Simple_Cheap_MMIC_Preamps.pdf


https://www.sv1afn.com/pga103m.html

Active antenna preamp for HF use:

http://www.g8jnj.net/activeantennas.htm


cheers, Graham ve3gtc

On 12/6/2018, "erik@kaashoek.com" <erik@kaashoek.com> wrote:

I did try a MICC as amplifier for an broadband loop but I found they either have insufficient gain (as their 50 ohm input impedance is badly matched with the loop) or when cascaded tend to get overloaded due to the huge dynamic range of the received signals.
But maybe you can find better MICC's then I tried.
Get one with the highest device voltage as second amp

--
Erik@Home





U3S Case front panel push buttons

Vernon Matheson
 

Hi all,

 

Has anyone found a better quality push button . I replaced the original with ones from Ebay…same type and they have not lasted that long. Get loose inside and start skipping and double clicking etc.

 

Vernon


Re: #qcx #problem Radio newbie and QCX large audio hum... #qcx #problem

KB3USG
 

Hey everyone,

I appreciate everyone's feedback and suggestions.

On 2018-12-03 18:09-0700, Ronald Taylor wrote:
First, No it is not right for this kit to have huge hum by touching the pot
and most stuff around it. Normally I would think you could get some hum by
touching the high side or the center pin (wiper) of the pot or by touching
the input pin 6 on IC10 But touching the pot shaft or housing or other
spots should not necessarily create lots of hum. This is grounded to the
circuit board.
Thanks for this, Ron. I did check out the pot as you suggested, and I
couldn't determine anything really physically amiss. However ...


My current plan is to:
* Recheck the board voltages and see whether anything has changed
radically from before.
I did this, and nothing was really very different from the readings in
the manual (or from my first check-out of the voltages across the
board).

However... when I was holding the board on one edge and my fingers
touched the case of the 7805 regulator, the hum went away. Really
sounding like a grounding issue.

I'm thinking that I've done some irreversible damage to the pot that was
not recoverable when I backed off the tension on the pot (I wouldn't
think this possible, so I'm grateful for some of the remarks in the
manual).

I'll hunt down a pot to put in place for now and see whether that makes
everything better.

And then get to this:

* (As part of my work peaking the BPF), take a couple of winds off
the T1 coil.
I'll keep updating the thread as I make progress.

Again, thanks to everyone who's reading these messages and musing to
themselves, and to those who have spoken up with some advice for me.

Thanks,
Paul
KB3USG


Re: Clock kit

John AE5X
 

I received the case for the clock kit (from Japan) after about 3 weeks and the electronic components 2 weeks later from Turkey. I had to be home for both deliveries since a signature was required - and I wasn't for the component delivery so had to go to PO to pick it up. A bit of a pita.

John AE5X


Re: Asking for consensus: BaMaTech housing power supply pinout #case #qcx

Peter LB0K
 

Why not check the polarity with a  voltmeter??


Re: QCX CW transceiver

David Wilcox K8WPE
 

Has anyone used any Q Dope or finger nail polish on the ends of the wires on the coil to hold the wires in place to make it easier to insert on the board?  In other kits the wires started to loosen while fiddling with them trying to get them all in the correct holes.

David J. Wilcox K8WPE’s iPad

On Dec 5, 2018, at 2:39 PM, Dave Redfearn <n4elm@...> wrote:

Ken,
I used 32 ga wire for my 80 & 60 Meter QCX builds on the main winding of T1 to get the winding to fit on the core.
I used the supplied wire for the three 5 turn links.

Tune up was normal.
I did have to remove 2 turns from the main T1 winding on the 60 Meter radio to have the capacitor set properly at ~ 3/4 mesh.

73 - Dave, N4ELM


Re: Active Aerials

Peter LB0K
 

Lots of good and accurate replies here, still I'd like to add my little bit.
John N3AAZ provided two good illustrations, and Allison good theoretical explanations.

My experiences have been very similar to both of their's.
Active miniwhips give a low visual impact unlike longwires, one must remember to consider the miniwhip and its ground connection as all important, PA7DMJ points out that the WEBSDR.org receiver at Twente Uni. runs from a miniwhip that IS GROUNDED TO A LARGE METALL ROOF through a short wire connection.

John's illustration shows the best basis -

with a direct electrical connection from the whip thru the transformer primary to a ground, or counterweight.

Transfer of common mode noise to the the receiver(s) is inhibited by the balanced feed from T to T1 and a local ground is used at the receivers. Their RF signal is differentially transferred from the antenna.
My installation was a miniwhip mounted at the top of a 4m fishing pole with the three earth wires in parallel connected down to a large zinc watertank. several radials led out from here to spread the ground.
I had a coax feed from the head, or preamp, through a common mode choke of a length (ca. 1m80) of RG174 wrapped through a toroid T140-61, and running into the KiwiSDR. With another CM choke in the box for the Kiwi. The choke just below the preamp made the best improvement.

Later I replaced the 5cm miniwhip with a professional type with an approx 30cm metal rod inside a radome, a transformer feed to the preamp, (2N3866 with emitter current 40mA) and transformer feed through a Belden dual/twin cable (110ohm) to the receivers. An isolating transformer/balun was used to feed through to the receivers and accept the preamp supply.
An even better installation, that lasted under a year.
Unfortunately this miniwhip was far too massive for the mast (silly me) and the mast failed due to overstressing from wind driven movements in November.

Main pointers are keep the miniwhip associated with a good ground, allow aerial currents to pass to the ground with low impedance, take a preferably isolated feed off to the preamp and to the receivers, Have 'strong' electronics in the preamp.

Keep the antenna as far away from the house(s) as possible, and from power lines. Esp. with coax feeds use CM chokes.

The loop antennas have a balanced pick-up field and give somewhat better results, esp. when one follows Chevdar's advice and suggestions. These have the balanced feed to the receivers, The  unbalanced loops with simple coax feed can also give acceptable results but an awful lot depends on how the package is installed and connected. And on the local conditions.

Try these out, and enjoy.


Re: Active Aerials

Erik Kaashoek
 

I did try a MICC as amplifier for an broadband loop but I found they either have insufficient gain (as their 50 ohm input impedance is badly matched with the loop) or when cascaded tend to get overloaded due to the huge dynamic range of the received signals.
But maybe you can find better MICC's then I tried.
Get one with the highest device voltage as second amp

--
Erik@Home


Re: Active Aerials

John VA7JBE
 

Hi Alison,

Is this the amplifier that you're talking about, based on the MAR-7 from MiniCircuits and described in the article below?

https://www.amsat.org/articles/wa8sme/preamp.pdf

Cheers,
John VA7JBE


Re: QCX CW transceiver

Dave Redfearn
 

Ken,
I used 32 ga wire for my 80 & 60 Meter QCX builds on the main winding of T1 to get the winding to fit on the core.
I used the supplied wire for the three 5 turn links.

Tune up was normal.
I did have to remove 2 turns from the main T1 winding on the 60 Meter radio to have the capacitor set properly at ~ 3/4 mesh.

73 - Dave, N4ELM


Re: Active Aerials

Erik Kaashoek
 

Allison,

Fully agree,
I have both the mini wip and the amplified broadband magnetic loop and from time to time I switch between them. 
As both antenna's are indoor and I'm living in a big city opposite to a cellular base station I tend to like the broadband loop more.
Substantial less noise and indeed directional.
But if you have a large metal roof you can have excellent result with a miniwip on top of the roof as you can hear on this web sdr
http://websdr.ewi.utwente.nl:8901/

--
Erik@Home


Re: Active Aerials

ajparent1/KB1GMX
 

Eric,

That's a decent loop amp.  Likely you will want more gain some a additional stage is warranted.

As to the original question on active whips...

Comments are constrained to antennas that have active elements typically less than .1
wavelength in physical and electrical height.

The biggest issue in dynamic range that is the internal amp should be low noise and resistant to
electrostatic damage.  There area a few that are ok out there.  The one I found the best was the
AMSAT active antenna from QST years back.  I built a few for work and tested them and generally
they were very good with an 8ft whip when in the clear.  That last few words are very significant
because those short active whips are known E-field antennas and generally need to be up high
or in the clear.  The effect is that buildings, power lines, and trees are RF paths to ground and 
you have to visualize all that stuff like a wire mesh over all those things.  Under the mesh weak
signals above it much stronger.  As a result a E-field antenna works better on the roof of a building 
than lower and next to it.  FYI for those wishing to build that antenna the fet supplier still exists.

Loops are less prone to it as they are not impacted as much near E-fields in the near field.  Though
testing done with ALP and PIXIL loops did indicate that one loop height up was generally better signal
and again away from buildings with high metallic content.  The gain of the amp and its noise figure are
both critical as loops though quiet also intercept only a small signal.

They both offer fairly wideband solutions for receiving antennas frequencies under 10 mhz where full
size antennas tend to get large.    The loop has the advantage of directionality that being helpful in
negating by nulling the noise out.    In all cases installation, feedline/power isolation, and sometimes
grounding are overriding factors to success.

Allison