Re: Bifilar - Trifler transformer function in Amplification
#5wPA
Thx Ron,
Makes sense and is what I expected.? So if bifilar provides a 1:4 impedance step, what would trifilar in the same configuration provide as a impedance step?
73
Timo
zr6tm
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Re: QDX build option- hybrid lo & hi version?
#qdx
Hi Stu
QDX has
4 BPFs in the front end (selection of the toroid here might be tricky, 37-2 or 37-6)
3 LPFs after the PA output
please study the manual for normal and hi-band
you'll figure out
I did some experiment with an LPFless QDX
it is possible...
73 muhsin TA1MHS
?
?
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Re: Bifilar - Trifler transformer function in Amplification
#5wPA
Hi Tim. In this case it is providing?a 1:4 impedance step up from the 12.5 ohm FET Drain to 50 ohms at the input of the low pass filter.
Ron
Thx Dave and Paul,
Looking at the snip I agree that the bifilar winding 1 connects the 12v supply to the drain of the mosfet.? Winding 1 then connects to Winding 2 to provide the PA output.? Sorry for this uneducated question, but what function does the transformer perform in this instance.? ??
73
Timo
zr6tm
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Re: Bifilar - Trifler transformer function in Amplification
#5wPA
Thx Dave and Paul,
Looking at the snip I agree that the bifilar winding 1 connects the 12v supply to the drain of the mosfet.? Winding 1 then connects to Winding 2 to provide the PA output.? Sorry for this uneducated question, but what function does the transformer perform in this instance.? ??
73
Timo
zr6tm
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What is the best way to track many U4B trackers with one call sign? Apologize?if this was discussed before but would like to know what format actually works well (routed correctly to all the WSPR websites).
73, Joe W2JEJ
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I'm not having good luck putting all four into a working chain.?
With the QDX USB attached to the Pi I see a serial QDX port with the Config | Setup | Other
tabs. I press the 'init' but I do not see any change in status or display options.
Does anyone know what I am missing? When I bring up JS8Call and select radio flrig flrig I see HAMlib errors.
Much more to learn.
John
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Hi Bryan
I had a similar thing happen on a QCX mini, the culprit was a burned up Q5...a BS170...
Strangely this started as a reduction in TX power, Q5, shunting the output to ground partially until it fully burnt out whereupon the TX output returned to normal along with a very signal deprived and deaf RX.
Good luck in tracking it down
73 Steve G4EDG?
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QDX build option- hybrid lo & hi version?
#qdx
Greetings all. I finally ordered my first kit (QDX) from Hans. Something I should have done a couple years ago had I not had a silly confusion about the nature of MFSK in general, Olivia (my favorite mode) in particular. I've been inactive for a decade & ready to start back in.?
Question- Is it reasonably possible to substitute a band or two from the hi band parts kit into a low band kit? Or is there more to it than just swapping out filter parts? Would the software be adaptable by user to reflect the correct band & band limits??
Might not be worth my effort if it requires much engineering know-how. I believe my assembly skills are up for the build, but my radio theory knowledge is admittedly weak. Han's instructions look excellent, just my speed! Looking forward to the process regardless.?
--
de Stu AI7AN
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Re: Bifilar - Trifler transformer function in Amplification
#5wPA
I presume, because your question is not sufficiently clear, that you are talking about a push pull amplifier, where a bifilar or two winding transformer is connected between the FET Drains and the power supply.? Sometimes there is a third winding that serves as the output winding.? Sometimes there is a separate transformer for the output impedance matching.
The Bifilar Transformer serves to bring DC power to the drains and is a Push Pull transformer.? One side will be going positive while th either side is pulled to ground by a conducting MOSFET.
That make sense?
Dave
Dear all,
On most class C and D amplifiers the IRF510 is followed by a trifilar or bifilar transformer toroid.? ?Can someone please explain what the function of the this type of transformer is.? (is it for impedance matching?) Google is just not providing me with a easy understandable answer.? ?
73
Timo
zr6tm
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Re: Bifilar - Trifler transformer function in Amplification
#5wPA
IMHO, the reason for trifilar is for tight coupling and balance
between the windings. For when "close" isn't good enough!
;-)
Paul
toggle quoted message
Show quoted text
Dear all,
On most class C and D amplifiers the IRF510 is followed by a
trifilar or bifilar transformer toroid.? ?Can someone please
explain what the function of the this type of transformer is.? (is
it for impedance matching?) Google is just not providing me with a
easy understandable answer.? ?
73
Timo
zr6tm
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Yes Cliff.?
I am now building up a PI for the QDX. Trying to get JS8CALL to work with FLrig.
I dont see a QDX in the 1.4.7 version of FLrig installed with apt-get install. SourceForge?
is my next stop.
John
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Re: DIY enamel scraper: modified seam ripper
I live my Knipex stripping tweezers, you can get up close to the toroid without nicking it or the other windings.?
Those tweezers come with 0.6mm jaws standard; there are also 0.5, 0.8 and 1.0mm replacement jaws available, per this document.???
Does anybody here remember Strip-X (Stripex?) that foul-smelling chemical wire stripper?? Dip the wire into the concoction, wait a few seconds and wipe with a paper tower.? Contained phenol and other nasty stuff.??
73, Don N2VGU
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Re: QCX-mini Adjustment and Alignment Issues: Excessively Sensitive Gain and Inability to Adjust IQ, Low and High
I'd like to thank everyone who has provided some excellent advice! You've given me some great direction and I will chase down each of the suggestions you've made. I'm a member of the Halifax Amateur Radio Club and there are a handful of us building QCX radios, but I happen to be building a mini and I'm farther along than some of the other folks (maybe I should've been a bit slower!). I'll go through everything systematically and I will get back to you with the resolution, but it may be next week by the time we've got things sorted as we meet on Sunday mornings. I've experienced a great number of generous people in this hobby and this group has been exceedingly responsive and kind. You're a credit to the hobby and I thank you for your assistance and the welcoming attitude of the group. I'll be back in touch once I've tested each piece of advice offered. -- Thanks and 73,
Tim
VE1XR
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Bryan, from those voltages it looks like you should first make sure you have good connections at the points labeled 5,6,7&8 on T1 in the instruction manual. Also make sure you installed 10K resistors at R1 and R2. If that is all correct, temporarily lift the wires labeled 5 and 8 on T1 out of the board holes and see if you have 2.5 volts on the two lifted leads, measured to ground from each.?
Unrelated to the voltage problem, but necessary to get a test signal to actually appear at the front end of the receiver when in the alignment modes, please?check for DC continuity ( with the rig turned off) from the center pin of the BNC to the C29 end of L3. if that isn't there use your ohm meter to find where it stops and correct?that solder joint.
Please do those checks and report back with your findings.
73 .. Ron
On Sun, Jan 29, 2023 at 2:57 PM Bryan Curl < bc3910@...> wrote: I seem to have killed my QCX+ receiver. It still receives but very very low sensitivity.
I may have overloaded the front end here in the shack by keying another radio nearby or it got damaged connecting to a Signalink USB interface. I suspect I overloaded the front end.
Im not sure where to start troubleshooting. There are several low voltages throughout the system starting with T1. Due to? the number of checks, I will attach a pdf showing them all.
I tried to factory rest and realign. The alignment was not possible due to low signals into that section. The oscillator worked but I could tell by the graphs and numbers that something was not getting into these sections loud enough.
Any help would be graciously appreciated. I do not have a scope but fairly proficient with all the other tools needed.
Kind thanks in advance.
--
regards,
Bryan, N0LUF
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Re: QCX+ Time Keeping Question
#clock
I miss them also but, I have bought those items and many other items from Amazon.
-----Original Message-----
From: Keith "Al" AG5GW <islandpiper51@...>
To: [email protected]
Sent: Mon, Jan 30, 2023 9:26 am
Subject: Re: [QRPLabs] QCX+ Time Keeping Question #clock
It's times like this I really miss Radio Shack.....needing more 3.5 MM stereo plugs, as usual. ?Thanks for the tips. ?I have both manuals open now and will proceed as shown. ??
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Re: QCX+ Time Keeping Question
#clock
It's times like this I really miss Radio Shack.....needing more 3.5 MM stereo plugs, as usual. ?Thanks for the tips. ?I have both manuals open now and will proceed as shown. ??
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Re: DIY enamel scraper: modified seam ripper
I'll make one out of an old hacksaw blade. Looks like it should work fine and be an easy homebrew.
Thanks for the idea
John K5MO
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Re: THANK YOU! I (We) Fixed it! Re: #qdx TS Suggestions? New QDX Worked Fine for 3 Days - Now Low Output Power after checking hi SWR
#qdx
Peter,
I am glad that you have your QDX back up and running.
Here are a couple of tips that may help you maintain the 'status quo' - your build is 9V - I would be inclined to use a 'buck-convertor' to enable you to reduce the 9V to perhaps 8.7 or 8.8.. reason your RF Output looks 'Maxed' and from experience if you are noticing the case getting 'warm' your BS170's are dissipating too much heat. IF THIS IS THE HAPPENING? You perhaps need some additional cooling?
Lots of options - Fan, Better Heat-sink, Lower voltage...
Keep an eye on the above and you should be okay!
73
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Re: DIY enamel scraper: modified seam ripper
You can save yourself some bandwidth by just using the product ID number (B003RWS8XE). This works on most popular site (eBay, Banggood, etc). Just type it into the search bar.
Jack, W8TEE
On Monday, January 30, 2023 at 09:13:51 AM EST, KC9REN <deanberg2044@...> wrote:
I do like the sandpaper idea but I have a Knipex enamel wire stripper and love the way it works. Presently $19.41 on Amazon.
https://www.amazon.com/Knipex-1511120-Coated-Wire-Stripping-Tweezers/dp/B003RWS8XE/ref=sr_1_1?crid=KY5L5HSY5GB3&keywords=knipex+enamel+wire+stripper+tweezers&qid=1675087696&sprefix=knipex+enamel+wire+stripper+tweezers%2Caps%2C118&sr=8-1
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Re: DIY enamel scraper: modified seam ripper
I use my wire cutters (very gently) to scrape the enamel, or an Xacto knife.? One thing I found is that my soldering iron temperature had been set too low (about 700 F).? Bumping it up to 800F made it much easier to burn off any remaining enamel.? I suspect that a fatter iron tip or a more powerful iron would also help, no doubt the small tip I am using (I usually do surface mount) cools down a bit when working with the toroid wires.
--
Paul Elliott - WB6CXC
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Ronald Taylor
JE Jesson
Paul - AI7JR
Donald S Brant Jr
Tim Delaney
Keith "Al" AG5GW
jjpurdum