Re: QSX 10W Linear PA Problem.
Alan,
thanks for the link.
73/72
John
M0JBA
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On 12 Nov 2021, at 11:11, Alan G4ZFQ <alan4alan@...> wrote:
The bias to Q203 and Q204 is not adjustable, but voltage measured at the gates is about 1V.
Looking at the BS170 data sheet, Vgs needs to be about 2 - 3V to turn it on.
Am I on the right track? John,
Yes, there seems to be something wrong with the bias.
This driver is a Softrock copy so here is a description of the bias circuit.
73 Alan G4ZFQ
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Re: QDX how to connect MS terminal?
On Thu, Nov 11, 2021 at 09:59 AM, Jim Campbell wrote:
used to be the designer and maker of QRP kits
Used to be? I would replace that with "is". Though the volume available is much smaller than what Hans produces and they come in limited batches, he has still been designing and producing qrp radio kits. And if you ever see an LNR Mountain Topper, that is Steve's design (though I am not sure if he gets a fair share of the credit or the money).
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Re: QSX 10W Linear PA Problem.
The bias to Q203 and Q204 is not adjustable, but voltage measured at the gates is about 1V.
Looking at the BS170 data sheet, Vgs needs to be about 2 - 3V to turn it on.
Am I on the right track? John, Yes, there seems to be something wrong with the bias. This driver is a Softrock copy so here is a description of the bias circuit. 73 Alan G4ZFQ
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QCX WARC Party - November 2021
Next monday,?November 15th?is the next?QCX WARC Party.
(note : I think we have lost Hans for the QCX parties, I see from the many spots he's having way too much fun in FT8/JS8Call with his QDX? ;-)
See?
And join the discord page under?#qrp-operation, to post your QRG, or other comments.
Report your results as a reply to this message (please don't start a new topic), then it's all in one place.
No scores, no prizes ... just plain CW fun.
The next regular QCX Challenge will be on November 29.
GL es 73/72,
Luc ON7DQ
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QSX 10W Linear PA Problem.
Hi all,
I have a 10W linear PA, with Rev 2 pcb, which is not performing as it should.
The output power is low.
The bias currents to Q207 and Q208 have been adjusted to 125mA each at 12V supply.
The bias to Q203 and Q204 is not adjustable, but voltage measured at the gates is about 1V.
Looking at the BS170 data sheet, Vgs needs to be about 2 - 3V to turn it on.
Am I on the right track?
Would someone with a functioning amp measure the gate voltage on their amp.
All suggestions welcome.
72/72
John
M0JBA
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Web site says it is out of stock, can we place an order anyway?
Thanks & 73 d e Joe NE3R
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Yes in the end we will get to a state where everyone one who initially wants one, has one; and where I am able to manufacture fast enough to keep up with ongoing demand. Much like what happened with the QCX. But harder for me this time because of the state the world?is in. We'll get there... patience!
73 Hans G0UPL
Honestly parts are scarce, and when the next batch goes on sale they may be sold in an hour or less. There is no shortcut, you must be on line when they go on sale. Watch here for the info. Eventually the hope is they will finally be plentiful but supply of critical components is the problem.?
Curt
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Seems like my 50199 got skipped for some reason. 73 ae5hn
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Re: OT: Congratulation JackW8TEE
Thanks, Jeff...it's appreciated!
Jack, W8TEE
On Thursday, November 11, 2021, 08:00:09 PM EST, Jeff | VA2SS via groups.io <jeff@...> wrote:
Hi Jack,
Yes, it is the digital edition. We have a government service here in Quebec called "Quebec National Archived Library". It is for citizen of the province of Quebec only. And we have access to a lot of free digital content, like magazine.... and CQ Magazine is part of the list. It is like a physical library when you are a member. You may borrow books, musics or magazines online using a software that manage the member subscription. At the end, you return back what you have borrowed within the time limit. :-)
Looking forward for the next article. :-)
73
--
Jeff | VA2SS
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Honestly parts are scarce, and when the next batch goes on sale they may be sold in an hour or less. There is no shortcut, you must be on line when they go on sale. Watch here for the info. Eventually the hope is they will finally be plentiful but supply of critical components is the problem.?
Curt
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One has to wait for Hans to announce when the next batch of QDX kits will be ready to ship.? Then? hope that when the web page is opened for orders of that kit a couple of days later, an order can be? submitted between others attempting to do the same thing.? When the count of the number of kits? remaining available decrements to zero within as little as 15 minutes, if an?order hasn't been accepted,? it's rinse and repeat when the next?batch of kits becomes?available.
On Thu, Nov 11, 2021 at 12:23 PM Gary Bernard via <garybernard2= [email protected]> wrote:
Can't you just order one from QRPLabs?
-----Original Message-----
From: [email protected] Notification < [email protected]>
To: [email protected] < [email protected]>
Sent: Thu, Nov 11, 2021 12:17 pm
Subject: [QRPLabs] Chat Notifications #chat-notice
A new chat has been created:
New
The QDX looks like a real game changer.? I would like to purchase one, but so does the rest of the world..
I realize that there is a backlog, and getting all the parts are difficult.?
Is there any way to get on
a list to purchase one as they become available.
Do not reply to this message to post to the chat. You can participate in chats only through the group's website.
A new chat has been created:
New
The QDX looks like a real game changer.? I would like to purchase one, but so does the rest of the world.. I realize that there is a backlog, and getting all the parts are difficult. Is there any way to get on a list ?
Do not reply to this message to post to the chat. You can participate in chats only through the group's website.
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Re: OT: Congratulation JackW8TEE
Hi Jack,
Yes, it is the digital edition. We have a government service here in Quebec called "Quebec National Archived Library". It is for citizen of the province of Quebec only. And we have access to a lot of free digital content, like magazine.... and CQ Magazine is part of the list. It is like a physical library when you are a member. You may borrow books, musics or magazines online using a software that manage the member subscription. At the end, you return back what you have borrowed within the time limit. :-)
Looking forward for the next article. :-)
73
--
Jeff | VA2SS
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Re: QDX CAT Control Issue?
I see also there appears to be a dropped a ¡®4¡¯ in the VFO.A statement:
VFO.A 707000
Which is probably why the frequency gets shifted bt a factor of 10?
On Thu, Nov 11, 2021 at 5:24 PM Gregg Myers via <gregg.w7grm= [email protected]> wrote: Hi Ryan, Hans,
I think I captured this frequency setting error today in?WSJT-X. The file ttached is a log file showing the CAT command error where the WSJT-X frequency gets confused. I had started a transmission in WSJT-X and the frequency?went OOB,?like it was devided by a factor of 10.? From the CAT log file, it looks like two FA statements?got inadvertently?jammed together,?or something like that. Here is the error:
RX;
VFO.A 707000
FA0000707FA000ID;
ERR: Band
RX;
when it should be more like this: RX;
VFO.A 7074000
FA00007074000;
ID; ID020;
It's not a frequent occurrence?from what I could see. My system information: - What?OS you are running: Windows 10
- What QDX firmware version you are running: latest 1.01b
- Whether you built the QDX for 12V operation (output transformer 3:2) or for 9V operation (output transformer 3:3): 9 Volt
- What power supply you are using: battery to 9V linear regulator to QDX
- Rev 1 PCB.?
- Built exactly as described in the manual
Cheers, Gregg W7GRM
Today I went into the console interface and turned on CAT logging so I can get some more data.?
@Karl, it looks normal there- the QDX starts up on an out of bounds frequency, I'm assuming so that it doesn't even accidentally start transmitting. I consider this a security blanket, since I have to manually set the frequency when I'm ready to operate. My finals feel safer that way ;-)?
I'll report back when I have data to share.
--
Ryan Flowers - W7RLF
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Re: QDX CAT Control Issue?
Hi Ryan, Hans,
I think I captured this frequency setting error today in?WSJT-X. The file ttached is a log file showing the CAT command error where the WSJT-X frequency gets confused. I had started a transmission in WSJT-X and the frequency?went OOB,?like it was devided by a factor of 10.? From the CAT log file, it looks like two FA statements?got inadvertently?jammed together,?or something like that. Here is the error:
RX;
VFO.A 707000
FA0000707FA000ID;
ERR: Band
RX;
when it should be more like this: RX;
VFO.A 7074000
FA00007074000;
ID; ID020;
It's not a frequent occurrence?from what I could see. My system information: - What?OS you are running: Windows 10
- What QDX firmware version you are running: latest 1.01b
- Whether you built the QDX for 12V operation (output transformer 3:2) or for 9V operation (output transformer 3:3): 9 Volt
- What power supply you are using: battery to 9V linear regulator to QDX
- Rev 1 PCB.?
- Built exactly as described in the manual
Cheers, Gregg W7GRM
Today I went into the console interface and turned on CAT logging so I can get some more data.?
@Karl, it looks normal there- the QDX starts up on an out of bounds frequency, I'm assuming so that it doesn't even accidentally start transmitting. I consider this a security blanket, since I have to manually set the frequency when I'm ready to operate. My finals feel safer that way ;-)?
I'll report back when I have data to share.
--
Ryan Flowers - W7RLF
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Re: QDX easy reverse polarity mod
Hi Steve,?
You might want to put a fuse inline with your power lead rated less than the max forward current of the diode or you will smoke the diode and the QDX if you have a power supply rated for just a few amps.? Otherwise a great idea and some HF rigs use this same method of reverse polarity protection.
Or, you can put a small full wave rectifier inline with your power leads outside of the QDX and nothing bad will happen no matter how you hook it to power.
73
-Mike
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#qdx another PA cooling improvement idea
#qdx
Hi Folks,? really love my new toy - this tiny QDX TRX and it work excellent. To prepare for longer FT8 sessions I tested and meassured a bit with the PA temp, as I it felt a bit high (first by fingertip measurements). At the Hermes Lt2, to increase the cooling. There the PCB to rail connection is used for primary heat transport and even the screw alone transports some temp to the case.... It could be an idea for a new hardware revision of the QDX to inlcude the PCB/Case connection into the PA cooling. I modified my QDX and was able improve the PA temp by 5 ¡ãC (10 Minutes test cycle) and I assume the result will be even be more convincing after a longer test cycle. How to do the simple mod (on your own risk ;-) ):
- removed the nut, washer and screw at the PA.
- while the QDX PCB is inserted in the case, use the existing whole in the PCB to mark the spot for the whole in the lower U profile of the case
- drill a 3mm whole and countersink from outside (see picture)
- replace original screw with a longer one with countersunk head
- gently tighten the screw?
Attention: do not tighten the connection to much, as there is a risk to crack the PCB.
I traced the following temperature curves at the surface of one of the BS170s (under the washer). Condition in both cases where the same:
- f = 7074,5 MHz
- U in = 9V
- I in = 1,07 A
- P out = 5W
- Duration = 10 Minutes
- Duty Cycle 50% (WSJT-X/FT8)
- Room Temp 21¡ãC
- Meassured with PeakTech Bench Type DMM 4090
With the original mounting method I meassured max 47,5¡ãC after 10 Minutes: After the mod, the temp was max on 42,3¡ãC. vy 73 de Alex, DK4FT ----------------------------------------------------------------------------------------------------- QDX - HW Rev 1.0 - U=9V - FW 1.01b - RPi4b with WSJT-x 2.5.1
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Re: QDX's DC connector common to 9V and 12V builds a potential problem?
Since the DC connector is the same the likelihood of that happening is a possibility. Alas, there¡¯s a confusing array of these connectors with little in the way of standards. I am only just now making some sense of them. Given that you probably have 12 volt devices that use the QRP Labs's standard 5.5x2.1 versions, you might want adopt something incompatible for your 9 volt build. Here¡¯s are lists that might be helpful. You¡¯ll probably need to find one whose power jack has the right dimensions for the PC board. This issue reminds me of when I first became interested in radio back when tubes were more common than transistors. At first I assumed that those who designed tubes had the ¡°wisdom¡± to make sure that only the right tube would fit in a socket. I soon realized that wasn¡¯t so. Every tube in my first radio had the same kind of socket. ¡ªMike Perry, WA4MP
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Re: QRP sub-bands for FT8
Since FT8 is often operated using split frequencies within the customary spectrum, a designated QRP frequency does little, and it would grab even more scarce spectrum away. I can¡¯t figure the dB reporting or -9 and higher dB that don¡¯t come back to my 100w. Just call regardless of the level you are sensing.?
curt
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I measured a lenght of? 223.75 cm of the 0.66mm wire, left over from winding L6, L4, and L7.? Therefore, I will have 5-lengths of 44.75cm wire to work with in making the bifilar and trifilar colls.? I am assuming that I will have enough wire to do the job.? From the photos in the manual, there appears to be plenty of extra wire when using 46cm per wire.?
Just wondering what others have found for this step
Thanks
Kent KC9LIF
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QDX's DC connector common to 9V and 12V builds a potential problem?
As I wait for the next round of QDX kits become available I've glanced through the manual and am impressed (again) with the thoroughness Hans has put into the rig and the documentation.
When I get the chance to build a QDX I think I'll opt for the 9V version.
My question is if you build for 9V (3:3 winding) and mistakenly apply 12V volts will you let out the magic smoke?
Since the DC connector is the same the likelihood of that happening is a possibility.?
I think the gotchas at this point are transmitting without a suitable antenna and DC reverse polarity. Is this another one?
If this is a possible point of failure, putting a big "9V DC ONLY" sticker on the case is one solution. Maybe a different sized DC connector is available with the same form factor could be used?
Just a thought, thanks for clearing this up!
--Al
WD4AH
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ON7DQ Luc
jjpurdum
Mike Perry, WA4MP
Retired Doc