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Re: Suggestion to speed-up QDX serial port development
¿ªÔÆÌåÓýStrangely enough, just ran across this picture of my Decwriter II (300 baud! ?30 characters per second!) that was hooked up to my S-100 machine running CP/M. ?Had one in high school that was a _serious_ upgrade from the KSR-33 teletypes (thought the teletypes had paper tape read/write mechanisms, so you could punch 5x7 alpha letters on tape with the appropriate program), and when I had the chance to buy one for my home computer, I jumped at it. ?8*) ?Just to be topical, you could hit <CR> on that or the VT-220 or VT-240 and it would be the console.? 73, Willie N1JBJ |
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Hi all,
The outcome of my tests with the QDX connected to the 50W class C PA (for FT-8) is as follows: - QDX with T1 3:2, operated at +10V DC - 50W PA operated at +18V DC - direct BNC 50 Ohm connection from QDX output to the PA input - direct 3.5mm PTT cable connection between them I get approximately 20W output power into a 50 Ohm D.L. on 20m without overheating of either equipment. I had to improve the QDX PTT +5V output line for that to work well: - 100R 0604 parallel to R10 470R, - 1k from Q12 drain to GND. This was necessary to come closer to the QCX PTT like output. With +18V DC the PA I.L. at RX (PTT = 0V) is at 0.4 dB on 20m, which is easily overcome by a QDX great sensibility. I am quite happy with what I got. 73 Bojan S53DZ |
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Re: What is an "acceptable" upper limit for QDX SWR?
On Fri, Aug 12, 2022 at 02:23 AM, Donald S Brant Jr wrote:
Andy: I am with you 100% on Anritsu menus!HP stuff was always my favourite. They seemed to have a habit of collecting around my workbench. At least the boss always knew where to come if he needed one ;-) ? -- - 73 de Andy - |
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QDX, Setting Receive Audio Levels
Hello all,
I'm curious about the general consensus for setting receive audio levels on the QDX. I've been using WSJT-X mainly in FT8 and FT4 with an occasional check in WSPR. I like the fact that QDX doesn't have AGC so that really strong signals won't squash weaker ones.? IIRC, receive levels in WSJT-X should be set so the level indicator is ~30 dB or so. But, under what band conditions does this apply? When the band is busy the level indicator can start hovering around 60 dB or so. An aspect of this is the wide graph's "Zero" levels for waterfall. I'm used to seeing a light blue in the waterfall (using the default color scheme) as the zero point but on some bands it's black and no amount of slider adjustment will bring it up. It seems like if you find a happy medium in FT8 and then switch over to WSPR, which almost always is going to have less activity, you have to switch over to terminal mode to bring audio levels up. Thanks! --Al WD4AH |
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Re: What is an "acceptable" upper limit for QDX SWR?
One key point to remember is that the manufacturers spec sheet doesn't
quite tell the truth in reality because to save their butts they deliberately underspec the ratings. I can prove that by saying that I have been running a bunch of QRP Labs beacon transmitters for some 10 years now, all using BS170's. The longest unbroken period of 100% duty cycle operation is probably about 5 years. Now then, in that time I have fed something like 2.4 watts DC input, obviously more than the? 0.85 watts specification. Remember once again that is continuous operation for at least 5 years non stop, and PROVES that spec sheet is very conservative. But I do ensure that the antenna is pre-matched before transmitting. That is vital, because as I have found out, if I run them into something like an SWR of 2.5 for example then they start failing. So the answer to the question falls upon the end user to do what any sensible person would do, use a properly matched antenna, and as engineers have known for almost 100 years now, you don't take take liberties with components. It's not like we haven't had the? time to discover this stuff ;-) - 73 de Andy - |
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Re: Suggestion to speed-up QDX serial port development
¿ªÔÆÌåÓý
Oh dear... seeing VT220 mentioned took me down the nostalgia terminals trip...
ASR33 on a DEC-10 at university
ADM3A on Prime750 at university. (? 32bit supermini similar to a VAX 11/750 but completely different )
Televideo 925 on Sage IV micros ( 68000 Unix / CPM-68k machine )
Kokusai KDS7362 on Sage IV micros ( 68000 Unix / CPM-68k machine )
CIT-101 (Poor man's DEC VT-100) on big Unix boxes or VAX 11/730 (I had the 11/730 to myself for 4 years!)
DEC VT-320 on a VAX 11/750 cluster.
The arrival of cheap 80386 based PCs early 90's blew the old minis out of the water for performance and that was the end of the glass TTY. I last used a terminal professionally in Summer 1998, so 24 years have passed.? That was on the 750 cluster which was
being replaced with a handful of Netware connected PCs. Even 24 years back you couldn't give away 80x25 or even 132 column VDUs. Nobody but nobody wanted them and I saw loads go into the waste skips, they didn't even go for recycling.? If I had only known
what they would be worth now. And had somewhere to store them. But this is from the man who junked an Acorn System1, Acorn System3, a Nascom2 and Data General Nova 1200 22 years back when moving house. Ha worth $1000 - $2500US to collectors now !
The question is: are people actually buying VDUs for $450?
Andy
From: [email protected] <[email protected]> on behalf of crichmon via groups.io <crichmon@...>
Sent: Monday, August 8, 2022 3:26 PM To: [email protected] <[email protected]>; 'D. Daniel McGlothin KB3MUN' <kb3mun@...> Subject: Re: [QRPLabs] Suggestion to speed-up QDX serial port development ?
How about this one: ? Just a simple search got this result.? Did the .fake site generate enough for this plus shipping? ? 73¡¯s Chris? kk7drm ?
From: [email protected] <[email protected]> On Behalf Of Hans Summers ? Hello Daniel ? This is a philosophical point.? ? Naturally we don't "need" a VT220 terminal. Any terminal emulator does the job.? ? But "Need" and "Want" are not necessarily the same thing. Every single one of us here must be familiar with this concept. Almost everything we do with amateur radio is unnecessary. We do it because we find it cool, we enjoy it, it's interesting, we learn from it and it makes us happy. The exact details vary from one of us to the next.?
? 73 Hans G0UPL
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Re: Qdx terminal tx test
#qdx
Hello Ken It's like a Morse key. The transmission stays on only while you hold the key down. 73 Hans G0UPL On Fri, Aug 12, 2022 at 2:08 PM KEN G4APB <lfoofui.nbz42@...> wrote:
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Qdx terminal tx test
#qdx
Anyone else have this problem?
The operating manual says¡¯ The following keys are used in the Transmitter test application: + increases the band - decreases the band
p Enable PTT (Highlights in YELLOW)
t Enable PTT and transmit (highlights in RED). But, pressing either p or t only gives me a brief transmission, not long enough to actually do any measurements with. Am I doing something wrong here? Would be nice if it stayed on transmit until The CAT timeout occurred. 73 Ken g4apb? |
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Re: 50w amp with qdx v3
Hi Evan That's right, but QCX+ and?QCX-mini also have a straight-through cable, the same. Only?the Rev 1 PCB of the QCX+ had tip/ring reversed (my stupid mistake); all subsequent PCB revisions are OK.? 73 Hans G0UPL On Fri, Aug 12, 2022 at 1:28 PM Evan Hand <elhandjr@...> wrote: High Andy, |
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Re: 50w amp with qdx v3
High Andy,
Unlike the QCX, the connection of the QDX to the 50watt amp uses a straight-through cable.? Since the Roing is the +5volt PTT signal, you do not need to worry about the tip connection.? There is not a connection to the tip in the 50watt amp. I used a 3.5mm stereo audio cable.? That is one with Tip, Ring, and Shield.? NOT a Tip, 2 Rings, and Shield. 73 Evan AC9TU |
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Hi Bela,
I would first check that the low-pass filter selection is working correctly.? You measure the voltage on the banded (cathode) side of the six diodes used to select the filter.? ?The two for the selected filter should be close to 0volts; the other four should be around 5volts.? You do the test using the terminal RF Sweep program to choose the bands without transmitting.? You should not transmit while doing the check. If the switching selection is OK, verify that you have the capacitors in the correct location.? I have not found a need to add or remove windings from the low-pass filter toroids.? I did have to adjust the wire spacing to tweak the output on the 20/30 shared low-pass filter L4.? That was the only one I needed to tweak. How is the receiver working? 73 Evan AC9TU |
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Re: Qdx v 3, 20m no transmit
#qdx
Hi Andy,
I agree with Alan on RF being the issue.? I had the problem with an off-center fed dipole where 40 had no issues, and 20 had a lot of RF on the feedline.? Installed an ugly choke (6 turns through a toroid) or clamp-on ferrites.? Both could cut down the RF enough in the shack to allow FT8 operation.? Ferrites on the USB cable worked on my first attempt also. 73 Evan AC9TU |
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Re: Qdx v 3, 20m no transmit
#qdx
On 04/08/2022 04:40, Andy AA0AM wrote:
20m recieves fine but when I try to transmit the led on the Qdx flashes 2 times indicating a sound problem and wsjtx loses cat control of Qdx all together.Andy, Typical symptoms of RF getting in. Some manage with ferrites on the USB cable but best to reduce the amount of RF in the shack. (Consider antenna configuration.) 73 Alan G4ZFQ |
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I struggle with low output power on some of the bands.?
80m: 5W - OK 60m: 5W - OK 40m: 2W - not OK 30m : 3.8W - not OK 20m: 2W - not OK I did reduce the L4, and L10 (LPF3) also L3 L8 (LPF2) inductors by one turn. Still it is too low on 20,30,40m bands. I am running on 12 Volts. T1 output transformer is quite worm. Supposed to have 2:3 rate. Would you have a suggestion? I am dreaming 5W on each of the bands.... Could it be that one of the BS170 is broken down? Does anyone experience with losing one of them? ? 73 de B¨¦la HA4BM |
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Re: Suggestion to speed-up QDX serial port development
¿ªÔÆÌåÓýHow about this one: ? Just a simple search got this result.? Did the .fake site generate enough for this plus shipping? ? 73¡¯s Chris? kk7drm ? From: [email protected] <[email protected]> On Behalf Of Hans Summers
Sent: Monday, August 8, 2022 3:18 PM To: [email protected]; D. Daniel McGlothin KB3MUN <kb3mun@...> Subject: Re: [QRPLabs] Suggestion to speed-up QDX serial port development ? Hello Daniel ? This is a philosophical point.? ? Naturally we don't "need" a VT220 terminal. Any terminal emulator does the job.? ? But "Need" and "Want" are not necessarily the same thing. Every single one of us here must be familiar with this concept. Almost everything we do with amateur radio is unnecessary. We do it because we find it cool, we enjoy it, it's interesting, we learn from it and it makes us happy. The exact details vary from one of us to the next.?
? 73 Hans G0UPL
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QDX with Bluetooth?
#qdx
#bluetooth
Hi Folks,?
is there anyone here who is thinking about adding a bluetooth interface for QDX?? This could improve the portability of it. QDX could be deployed very close to the antenna with some battery and no need for long USB cable. Quite ideal for field operations. I think.? It is just an idea.? 73 de B¨¦la HA4BM |
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Qdx v 3, 20m no transmit
#qdx
Andy KF0EZV
Hi,
On wsjtx..40m band works great, 20m recieves fine but when I try to transmit the led on the Qdx flashes 2 times indicating a sound problem and wsjtx loses cat control of Qdx all together. Works fine on 40m though. I could work 40 all day but as soon as I try to TX on 20, mayhem ensues. All my volumes are @100% per the manual. Tried on raspberry pi 4 and a windows machine as well. Any thoughts or similar experiences? Thanks- Andy |
Bela Mucs