Re: Hermes Lite 1 : RM Italy BLA 350 : QRP Labs 10W Linear
On Sat, Jul 13, 2024 at 11:36 AM, G8JCF wrote:
The 17dBm output is very attractive, but I'm not sure if it's variable, eg if the "drive control" in the various SDR s/w can control the drive level, or if the drive level is fixed at 17dBm
I've taken a look at the HL2 schematics, RFFrontend.sch and PA.sch - and the drive to the 17dBm connector, "RF1", and the drive into the 5W PA come from the same pins on the FPGA, so it looks like the RF1 RF level should be variable. Looks like I'll just have to hookup the 50ohm dummy load and 'scope the signal at RF1 and hopefully find out that it's fully variable, now that would be a neat solution. 73 Peter - GM8JCF
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Re: Hermes Lite 1 : RM Italy BLA 350 : QRP Labs 10W Linear
On Fri, Jul 12, 2024 at 11:02 PM, Steve G4EDG wrote:
I reduced the attenuation and was able to drive the amp to the full 100w with 5w.
Hi Steve That would mean voiding the warranty, and I'd rather not risk damaging GBP 1,000+ kit if I can do a solid solution with QRPLabs ultra-stable 10W Linear Amp BTW, do U know where I can get my hands on a BLA-350 plus schematic so that I can add it to the documentation of my BLA-350 plus ? Thank You Peter - GM8JCF
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Re: Hermes Lite 1 : RM Italy BLA 350 : QRP Labs 10W Linear
On Sat, Jul 13, 2024 at 06:15 AM, John AE5X wrote:
And here is another solution from EU1SW. Costly but offers 14-bit, 6m and 160m and power to run your amp to full output:
I've already got the HL2, the EU1SW is basically an HL2 with a 20W Linear in an enclosure for about USD400 more than what I paid for the HL2 itself. The QRPLabs 10W linear is about USD70 delivered inc taxes etc, so all I need to do is add some relays, an enclosure, 5 connectors, and of course build the QRPLabs kit, which all in all should come in at less than USD150 (assuming that I buy all new parts) Thanks for the suggestions Peter - GM8JCF
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Re: QMX transmits fine, but no receive
Still waiting for the replacement PCM1804, but the Chipquik arrived.
What a great stuff, highly recommended. Desoldering within 2 minutes and no issues.
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Re: Hermes Lite 1 : RM Italy BLA 350 : QRP Labs 10W Linear
On Sat, Jul 13, 2024 at 05:45 AM, ajparent1/kb1gmx wrote:
So far you have given a bunch of suggestions that does not get him
that 10W and a few that can barely do what he already has. So stop
polluting the topic with wild and inapplicable ideas.
Thank You Allison, I was beginning to feel like Alice in Wonderland !! The 17dBm output is very attractive, but I'm not sure if it's variable, eg if the "drive control" in the various SDR s/w can control the drive level, or if the drive level is fixed at 17dBm - I've read lots of manuals but so far haven't found anything which states that it is indeed variable, and it always seems to be referred to as the "fixed 17dBm output" The variable element is required because here in UK for example there is a 100W PEP max license condition for 60m, 32W PEP max license condition for most of 160m, and of course the general principle to not use more power than is required, so it would be much more convenient if I could just adjust the "drive control" in eg Thetis SDR s/w, rather than fiddling about with different attenuators, although the 17dBm level would be just within the safe operating range of an electronically controlled RF attenuator eg  not as convenient as the on-screen "drive" control, but doable. Once again, thank you Peter - GM8JCf
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To be precise for transmitting WSPR on 20m:
the actual TX frequency must be inside the mentioned block for WSPR:
20m: 14.097000 – 14.097200 MHz
Now if we use the Beacon mode of a QMX machine then we have to choose the frequency exactly inside that band. For example 14.097130 MHz
But if you do the WSPR using for example the WSJT-X program then by choosing the WSPR mode you get set the 14.095600 MHz. To get the actual transmit frequency you have to add an offset set in the WSJT-X program. Normally this offset is set to 1500Hz. So if nobody changes that all WSPR transmissions would be at 14.097100 MHz. This would be very unfortunate. It is a very good practice to change this offset. For the mentioned example of the output frequency 14.097130 MHz the offset would have to be 1530 Hz.
--
73 Bojan S53DZ
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Re: Intermittent QDX transmit failure on one band
Yes, exactly. The toroids are the ones to worry about.
The 47 uH molded inductors suffer in a different way. They are a bit brittle and are subject to physical damage. That too can shut down an LPF by denying PIN diodes their required forward bias current.
JZ
Thanks John! I'll start with those.
Just to be clear, when you're talking about checking the inductor leads first, you mean the hand-wound toroids (L2-L4, L6, L8, L10)? As opposed to the L1, L5, L7 and L9 radial inductor components?
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Re: Intermittent QDX transmit failure on one band
Thanks John! I'll start with those.
Just to be clear, when you're talking about checking the inductor leads first, you mean the hand-wound toroids (L2-L4, L6, L8, L10)? As opposed to the L1, L5, L7 and L9 radial inductor components?
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Re: Intermittent QDX transmit failure on one band
Leigh,
Solder joints can behave like this. Imagine surfaces pulling apart as they cool and shrink.
With focus on the 20m LPF, I suggest checking the inductor leads first. A poor joint that is the result of inadequate enamel removal can wreak havoc.
Next comes the capacitor solder joints, with emphasis on the ground leads. Good solder joints need heat and the inner ground? planes suck that away from the joint.
If after all that you suspect something is wrong with PIN diode switching, a voltmeter and Hans' excellent circuit operation description comes to the rescue.
I think the most likely is the first possibility, inductors,? though.
JZ KJ4A?
I have a QDX (board rev 3a) for 80-20m that I'd used successfully on a number of outings. On a recent SOTA attempt, however, transmit on the 20m band stopped working after about 15 minutes. I switched to 40m and that transmitted fine. But even after rebooting a couple times, I could not get transmit on 20m to work again.
When I got home and put the QDX on the bench, it worked fine again to transmit on 20m. Troubleshooting intermittent failures is fun!
On the day of the 20m transmit failure, the temperature was cool out, maybe about 45° F (7° C). That was the coldest conditions I had tried operating in. So I'm wondering if there's a small crack in some component that caused an issue when cooled, something that's part of the diode band-switching circuitry.
Which components should I focus on as the most likely culprits for an issue like this?
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So grateful for Jeffrey Moore, W1NC, who can figure out where we went wrong with our QRP Labs kits. Admittedly I do not quite have the tech chops, in spite of my enthusiasm for kit building. But Jeffrey got my QMX working and totally explained in detail what all he fixed. Here's the kicker: all Jeffrey asks for is a donation to cover parts/labor/postage, which he leaves entirely up to you. What an incredible service he does for those of us who need the help! Kudos to Hans for these ingeniously designed kits, and to Jeffrey who can solve the mysteries we sometimes create! Eric AC6NT
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Intermittent QDX transmit failure on one band
I have a QDX (board rev 3a) for 80-20m that I'd used successfully on a number of outings. On a recent SOTA attempt, however, transmit on the 20m band stopped working after about 15 minutes. I switched to 40m and that transmitted fine. But even after rebooting a couple times, I could not get transmit on 20m to work again.
When I got home and put the QDX on the bench, it worked fine again to transmit on 20m. Troubleshooting intermittent failures is fun!
On the day of the 20m transmit failure, the temperature was cool out, maybe about 45° F (7° C). That was the coldest conditions I had tried operating in. So I'm wondering if there's a small crack in some component that caused an issue when cooled, something that's part of the diode band-switching circuitry.
Which components should I focus on as the most likely culprits for an issue like this?
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QCX WARC Party - July 2024
Hi all,
?
next Monday, July 15, is the next QCX WARC Party.
?
See for all info
?
Join the discord page in the #qcx-qrp-operation channel to post your QRG (and mode) or exchange other info, complain about the weather ... or just have a chat with other QRP Labs friends ...
?
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 fun.
?
The next QCX Challenge on the regular bands will be on July 29 ! ?
?
73 es GL,
Luc ON7DQ
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WSJT-X has a band/freq selection window lower left. These are click selectable on Windows 7 on up. Click on your choice and radio instantly displays the freq. I am sure you already know this but I state it to make sure we are on the same page of the same book!
--
73
Karl
KI4ZUQ
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Could someone provide a circuit description for Q202 and Q201 in the Driver_Bias part of the schematic?
I'm also have a problem setting the bias on Q207 (Q208 is OK). I increase the pot to approximately 90 percent, at which point, it suddenly jumps to an excess bias amount. Way too touchy to set it to +125 mA. Could I have a bad pot? This happens regardless whether I set Q207 first, or second.
Thanks a bunch!
- 73, John, N0TA
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Re: First QSO in 45 Years! FT8 on 20m with QMX
That is fantastic, welcome back. You need to try Parks On The Air. This is a real good way to get your CW speed up. It's a short exchange and lots of fun. POTA has a great web site.
On Sat, Jul 13, 2024 at 11:53?AM WB0ZJJ-Alan via <alanmcdonley= [email protected]> wrote: 50 years ago the great hams of Salt Lake City helped me to get my ticket, build/checkout an HW-101 100 watt radio, and get on the air with CW at 13WPM and SSB. After about 5 years on the air, I sold all my gear and left amateur radio behind (but kept the ticket renewed for sure).
TODAY! First "QSO" in 45 years. Since my CW copy is slow with frequent missed characters, I used WSJT-X in FT8 with my newly built QRP-Labs QMX rig on 20m for my first contact attempts.
I strung up a 20m EFHW about 5 feet off the ground, and checked the SWR. Not great - between 1:2 and 1:3 but what the hey, we'll see what happens.
I sent a CQ QRP and checked fskreporter.?I was getting out!, and was even more surprised when someone actually responded with my call. WSJT-X noticed the reply and auto-sequenced the QSO - Pretty cool.
240713_135645 14.074 Tx FT8 0 0.0 1604 CQ QRP WB0ZJJ EL96
240713_135700 14.074 Rx FT8 -18 0.1 1603 WB0ZJJ WA6GXQ FM06
240713_135715 14.074 Tx FT8 0 0.0 1604 WA6GXQ WB0ZJJ -18
240713_135730 14.074 Rx FT8 -18 0.1 1603 WB0ZJJ WA6GXQ R-11
240713_135745 14.074 Tx FT8 0 0.0 1604 WA6GXQ WB0ZJJ RRR
240713_135800 14.074 Rx FT8 -14 0.3 1603 WB0ZJJ WA6GXQ 73
I entered the QSO into??as my first logbook entry and hope to see it confirmed.
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Re: QMX+ is completely dead after unsuccesful firmware update.
When you force firmware update method be sure you are connecting between AUX2 and Ground. I looked at the?picture and connected between the two red arrow points. Be sure you are connecting between either of the RED arrow points and either of the GREEN arrow points. If you go between the two red arrow points your computer will give you the error message. I and a friend did the two red arrow points..duh!
Mike WA8UOC
I tried to update the new firmware 1_00_020 with a laptop.?
The USB connection was a little bit strange as the laptop did not expand the QMX device icon to show it?s contents.
I ignored that strange behaviour and dragged the firmware file to the QMX device icon and it seemed to me that the file transfer started.
But immediately thereafter, the laptop showed a message "USB connection aborted" or something like that.
QMX did not react to the power button, (or maybe did, but the display did not activate).
I tried to use the AUX - GND wire method to force the QMX to firmware update mode, but no success. The laptop did not detect the QMX.
It is obvious that there was some problem with my laptop. The laptop was running with battery power.
Now using my desktop PC does not help, the PC does not detect the QMX.
What to do?
?
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Re: Hermes Lite 1 : RM Italy BLA 350 : QRP Labs 10W Linear
Don,
Its 350W and 1db compression is likely above that.
if he gets 260 hes less than 3db down. If the QRPL amp
is run at 15-18V it will give you more I usually see 11W
at 13.6V and at 16V more like 15W. Also the amp at
20V will produce 25+W. So there is margin there.
That and most devices for that power level might tolerate
20W before becoming fuzes. The BLA350 has a input
sensor and will trip if over 13W.
Myself I'd check the BLA for input attenuator as the apparent
gain is about 14db. Two cases for that, bipolar devices that
would be typical, or Mosfet with attenuator. Looking at the
schematic it has Mosfets and a input attenuator.
--
Allison
------------------
Post online only,?
direct email will go to a bit bucket.
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First QSO in 45 Years! FT8 on 20m with QMX
50 years ago the great hams of Salt Lake City helped me to get my ticket, build/checkout an HW-101 100 watt radio, and get on the air with CW at 13WPM and SSB. After about 5 years on the air, I sold all my gear and left amateur radio behind (but kept the ticket renewed for sure).
TODAY! First "QSO" in 45 years. Since my CW copy is slow with frequent missed characters, I used WSJT-X in FT8 with my newly built QRP-Labs QMX rig on 20m for my first contact attempts.
I strung up a 20m EFHW about 5 feet off the ground, and checked the SWR. Not great - between 1:2 and 1:3 but what the hey, we'll see what happens.
I sent a CQ QRP and checked fskreporter.?I was getting out!, and was even more surprised when someone actually responded with my call. WSJT-X noticed the reply and auto-sequenced the QSO - Pretty cool.
240713_135645 14.074 Tx FT8 0 0.0 1604 CQ QRP WB0ZJJ EL96
240713_135700 14.074 Rx FT8 -18 0.1 1603 WB0ZJJ WA6GXQ FM06
240713_135715 14.074 Tx FT8 0 0.0 1604 WA6GXQ WB0ZJJ -18
240713_135730 14.074 Rx FT8 -18 0.1 1603 WB0ZJJ WA6GXQ R-11
240713_135745 14.074 Tx FT8 0 0.0 1604 WA6GXQ WB0ZJJ RRR
240713_135800 14.074 Rx FT8 -14 0.3 1603 WB0ZJJ WA6GXQ 73
I entered the QSO into??as my first logbook entry and hope to see it confirmed.
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Re: QMX S9+ noise on receive
My I/Q diagnosis looks much worse. I can see the 90 deg phase shift clearly but the signals are extremely noisy. My receive sensitivity seems to be fine though. I compared it to my K3 with an antenna switch and it’s very close with the K3 having a slight edge. That said, the receive audio is pretty nasty compared to my silk smooth K3. Listening to CW on the QMX for half an hour gives my a huge headache.
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Re: QMX S9+ noise on receive
James,
Check that you have properly removed the enamel insulation and have a good solder joint at the 60 m end connection to L401.
JZ
My 60-15M QMX hears 1 microvolt easily on 40 through 15 but needs an S9 signal or better on 60 meters. I'm not going to operate on 60 meters so I wont be fixing it but wanted to post this in case it helps.
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Dirk
Leigh KG7WED
ON7DQ Luc
Karl
WB0ZJJ-Alan