I believe Zener diodes have an internal capacitance that may render them problematic for this purpose. But - I am not sure of this.
Lee KX4TT
On Tuesday, 9 November 2021, 11:50:57 am GMT-5, Evan Hand <elhandjr@...> wrote:
Fred,
Protection of the IC5 is needed.? Seems like the BS170s are easy enough to fail, especially in a portable operation where the antenna might not be ideal.? They are also relatively easy to replace.? Better would be a way to protect the BS170s.? Maybe with Zener clamp diodes there.? That would protect from a high SWR voltage spike killing the BS170s and then taking out the 74ACT08.? Current limiting the input could help with the output shorted condition.? Both would be good things to add if portable is the goal.? The current limiting could be external to the QDX.
As with you, I have not really analyzed the issue.
73
Evan
AC9TU
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Fred,
Protection of the IC5 is needed.? Seems like the BS170s are easy enough to fail, especially in a portable operation where the antenna might not be ideal.? They are also relatively easy to replace.? Better would be a way to protect the BS170s.? Maybe with Zener clamp diodes there.? That would protect from a high SWR voltage spike killing the BS170s and then taking out the 74ACT08.? Current limiting the input could help with the output shorted condition.? Both would be good things to add if portable is the goal.? The current limiting could be external to the QDX.
As with you, I have not really analyzed the issue.
73
Evan
AC9TU
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A wish for later version of the QDX :-)
I would be nice to have a PTT output , that is triggered 200 Milliseconds before TX is actually enabled -
and a TX inhibit input - to use for a SWR and (to high) TX PW out bridge.? ??
73 - Knut
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That should work fine, as long as it's package, pin compatible, and fast "AC".?
It's being used as a "hard" driver for the finals.?
I wonder if it couldn't be protected from damage by Zener clamp diodes on the output but I have only dreamt that up, not analyzed it yet.
Fred W0FMS?
On Tue, Nov 9, 2021, 9:18 AM Knut Steinar Fremme OE4KSF via <steinar= [email protected]> wrote: Trying to find a supplier in Europe for the QDX - IC5
The IC onboard have only the letters?74ACT08 on it and only manufacture I find is FAIRCHILD in USA
But I find 74ACT08SC in stock in Europe?
From the specs I see no difference on this to versions ?
Maybe Hans could pop in here and verify that the SC version is ok for the QDX ?
73 - Knut??
?
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Trying to find a supplier in Europe for the QDX - IC5
The IC onboard have only the letters?74ACT08 on it and only manufacture I find is FAIRCHILD in USA
But I find 74ACT08SC in stock in Europe?
From the specs I see no difference on this to versions ?
Maybe Hans could pop in here and verify that the SC version is ok for the QDX ?
73 - Knut??
?
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I made a few comparisons with my QDX on 40m in order to learn what input voltage is required to produced a desired output. I was surprised at how low of an input voltage the QDX would continue operating:
--
John AE5X
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The proper way to count turns of a toroid is the number of times the wire passes through the center of the core.? DO NOT count the turns on the outside of a core!? I also count 37 turns on the photo.
Mark, NK8Q
Looks like 37 (in the picture) to me.
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Re: QDX - notes after day 1
Hi Steve,
You could use JS8 this is give you plenty of room to exchange more the just a report of locator and signal strength
Maybe we could arrange some Sunday evening net for QDX users
73 Frans PE0F
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That's why Linux is so much better than Windows...it will run reasonably well on old hardware, and superbly well on new hardware. If Linux boots quickly from the same drive that Windows takes 15 minutes to boot from, the hardware and in particular the hard drive is common: it's Windows that is at fault.
Hard hat firmly on!
73
Roger
8P6RX
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On 2021-11-09 10:39, Shirley Dulcey KE1L wrote:
15 minutes?? Windows 10 shouldn't even take 15 seconds to boot. If it takes 15 minutes on your system you are doing something horribly wrong. Trying to run it from a spinning hard drive qualifies as horribly wrong :)
?
I do wonder if some people having non-transmit issues have a windows audio set up issue. If the windows audio mixer applies some kind of scaling, for example. I normally use Linux but I didn't have any problems when I tested on Win10 (my PC can boot into Win10 if I insist and if I'm prepared to wait 15 minutes).?
?
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15 minutes?? Windows 10 shouldn't even take 15 seconds to boot. If it takes 15 minutes on your system you are doing something horribly wrong. Trying to run it from a spinning hard drive qualifies as horribly wrong :)
? I do wonder if some people having non-transmit issues have a windows audio set up issue. If the windows audio mixer applies some kind of scaling, for example. I normally use Linux but I didn't have any problems when I tested on Win10 (my PC can boot into Win10 if I insist and if I'm prepared to wait 15 minutes).?
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I think that Windows sound card issues can be one of the primary reasons things don¡¯t work or stop working.?
Don
W6CZ
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Looks like 37 (in the picture) to me.
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I've used mine for WSPR as well but am not comfortable running the full 5W output for two minutes. Turning the supply voltage down to 9.2V on 40m produces 2 watts out and the QDX runs cooler.
--
John AE5X
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Mine shipped from US warehouse on 11/5 arrived on 11/8? USPS.
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You counted correct. It may have had 1 taken off because to get the bandpass to peak properly. Same for L3 and L1, I think they are 1 or 2 less than the text, if the QCX+ pictures are the same as QCX mini pictures.
Mike/w1mt
On Tue, Nov 9, 2021 at 5:01 AM < kc2wan@...> wrote: Perhaps this is a silly question.? Why does the image of the transformer toroid in the QCX+ assembly manual show 5/5/5/37 windings when the manual indicates it should be 5/5/5/38? Am I misunderstanding how to count windings?
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Re: QDX Surface Mount inductors
Thank Hans,
Kit now built worked first time and software updated, however, I need to learn how to fly WSJT-X , I get a full 5 Watts on TX with 2:2 as suggested for 12V operation, I will plot the harmonics, and send you, I will try adding some caps across the inductors to bring them self resonance to 1MHz and see what happens first then replace them with your wired inductors, if unsuccessful.
PS windows 10 was tiresome with the com port, first it work then it lost it, and took awhile to get back.
What is the duty cycle at 5 Watts?
73
Andrew
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Also with fldigi, be sure to check the TX level attenuator in the lower right corner. Mine was set to -3 dB, had to set it to 0 to get it to work.
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Hi Phil
The default "rising edge threshold" setting in the QDX configuration screen is set to 80%. That's why it only seems to work when the WSJT-X slider is set to maximum. I believe the WSJT-X slider is logarithmic so the effect of reducing it is disproportionate, I mean 80% WSJT-X slider would correspond to much less than 80% amplitude in voltage terms. Anyway there's no point anything other than 100% because it doesn't alter the transmit output power at all, as it would on a conventional SSB transceiver.? I do wonder if some people having non-transmit issues have a windows audio set up issue. If the windows audio mixer applies some kind of scaling, for example. I normally use Linux but I didn't have any problems when I tested on Win10 (my PC can boot into Win10 if I insist and if I'm prepared to wait 15 minutes).?
73 Hans G0UPL http://qrp-labs.com
-------- Original message -------- From: "Phil Hazelton via groups.io" <philhazelton@...> Date: Tue, Nov 9, 2021, 1:04 PM To: [email protected]Subject: Re: [QRPLabs] QDX arrived Hi all, Just finished mine between 3.7 and 4.5 W with 12 V depending on band. FWIW, I¡¯m running Windows 10, and WSJTX 2.4.0. I set the Rig to Kenwood TS440S as recommended, but was having trouble band switching and there was no Tx, I changed to TS480 and everything worked perfectly. Also, the wsjtx power slider MUST be set to 100%, other wise you will not get any output power at all. PSK reporter spots all over Europe, furthest so far 3385 Km into Russia from UK. 73 Phil? G8PJH? On 9 Nov 2021, at 05:21, Don Melcher <don@...> wrote:
? And it¡¯s the perfect size!! Nearly identical to a RaspberryPi. This os going to be fun.?
Don
W6CZ
DM07bk
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Hi all, Just finished mine between 3.7 and 4.5 W with 12 V depending on band. FWIW, I¡¯m running Windows 10, and WSJTX 2.4.0. I set the Rig to Kenwood TS440S as recommended, but was having trouble band switching and there was no Tx, I changed to TS480 and everything worked perfectly. Also, the wsjtx power slider MUST be set to 100%, other wise you will not get any output power at all. PSK reporter spots all over Europe, furthest so far 3385 Km into Russia from UK. 73 Phil? G8PJH?
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On 9 Nov 2021, at 05:21, Don Melcher <don@...> wrote:
? And it¡¯s the perfect size!! Nearly identical to a RaspberryPi. This os going to be fun.?
Don
W6CZ
DM07bk
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My QDX has been on the air for a day, so far on 40m only.Receiver performance has exceeded my expectations.I have built it for 12V operation and am running with 11V at the moment - lots of QSOs with signals heard in 3 continents. Attached image is from PSKReporter.
?
I am using the?same computers and?USB leads as my main rig which?runs up to 100W, but I have found that RF feedback is a problem with?the?QDX even at 2W.
The symptoms are dropping the USB CAT control and QDX going into oscillation. This self-oscillation continues when WSJT is closed. I would recommend that output is monitored with a power meter or receiver. Without monitoring it is difficult to spot and could lead to overheating - I wonder if that may be the cause of some transistor failures.
The feedback problem has been resolved with ferrites on all leads :-)
?
I managed to break one of the axial inductors. My fault - I just didn't realise how brittle and fragile they could be. Easily fixed for 5p, but take care when bending the leads.
On my QDX one of the ICs did just foul the case by a fraction of a mm. I quick scrape with a scalpel fixed it, but it would have been enough to drag the IC off the PCB if any force had been used.
?
It would be nice to be able to identify other stations as QDX users. Calling 'CQ QDX' would just confuse all other stations. Any ideas ?
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Lee
Knut Steinar Fremme OE4KSF
Fred Spinner
Shirley Dulcey KE1L
N3MNT
Andrew Lenton