Re: QMX Capacitor Swap Gives Lower Power.
#qmx
If you are referring to me....bias is at 30.....
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Evan, it¡¯s my understanding that 002 fixed one source of the pops but left a key up one.?
--
Colin - K6JTH?
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My apologies if I wasn't clear.?
I did not mean to imply that all non US orders had been shipped. Only that quite a number of orders, both US and Non-US, got shipped today. The US/Canada have a different automated bulk shipping process to the rest-of-world. And there was a glitch on the non US/Canada bookings that meant that for each one, 3 tracking IDs got created though only one of the these is real.
If you didn't get any shipment notification emails and your status isn't changed it means yours isn't sent yet. 73 Hans G0UPL
On Fri, Jul 14, 2023, 9:10 PM < m0icr@...> wrote: Hans,
I am a none non-US/Canada customer and selected TNT/FedEx Option. No Tracking number sent, no change in shipping status. Checked Spam Filter. Order number 72385, please advise on order status, confused.
73, M0ICR
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I grew up on Mainframe computers in the late 60s. Worked for IBM FSD, but was contracted to Cal Tech JPL to program for the first moon orbiter tracking, guidance and data processing. We did it all on the IBM 7094 with the 64 bits of significant figures floating point upgrade, 2 36 bit words. Octal notation was the way of the day. I still remember those 6 foot free standing tape drives with the vacuum columns as well as the first disk drives with a single disk about 2 1/2 feet in diameter sitting in a enclosure about 6 foot high. 64 bit floating point was the big deal of the day. Later we went to IBM 360s and disk drives with disk packs that operators could change depending what was on each pack. Pin feed printers that could eject a full box of paper in a minute or so if it went crazy. Fun days. Another group was doing stuff on the Univac that was supposedly the fastest thing out there. The best part was being part of the group that was invited to watch the first pictures come back from the orbiter, line by line on a huge screen. Took maybe 10 minutes to fill out that first picture. Boy have things changed. I also still have my K&E log log decitrig sliderule.
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Show quoted text
After leaving MPLS Honeywell in 1960 I joined Control Data in a production division called IDP. I helped unload a truck full of stuff we purchased from the General Time division of a company located in Connecticut.It was a computer, had a compiler, concentrator and other perferals, I¡¯m old, can¡¯t remember everything. With a couple of exceptions, all tubes. The compiler had about 300. 6A37,s maybe? 12A37? We set up an assembly line. Got it to work and sold a system to the USPS. I Often think their still using it. Gary W0CKI? ? That picture of a cordwood assembled module - tube included - took me back to 1965 memories.
It's been YEARS since I assembled cordwood modules for a Boeing prototype??Data Storage And Processor (DSAP) system for the USAF complete with a magnetic core memory.
As an aside, I had all of the Tech's (I was one of them) save? the diode lead clippings because they had a high Silver content. Someone eventually ended up with 10's-of-pounds of silver!
73? Dick/w7wkr at CN98pi Jim Campbell,
The attached image was scraped from the Hackaday web site. It is an
IBM flip-flop module using a dual triode vacuum tube. You probably saw
these in abundance in your sleep! I first encountered things like this
being sold at a surplus sales house called N. Silverstein's in
Detroit. As transistors and IC's obsoleted tons of old hardware, stuff
like this became available for parts, and for cheap. It helped to fuel
my early teen hobby days in the 1960's.
I went on to work at IBM in Lexington KY and designed chips for use in
electronic typewriter products. Many of our staff came from Endicott.
Later I found myself running the R&D operations for the Inkjet Printer
Division for IBM and later Lexmark.
Regards, JZ KJ4A
On Fri, Jul 14, 2023 at 1:27?PM Jim Campbell <jecspasc@...> wrote:
>
> The Army (ASA) sent me to IBM CE School after which I maintained an IBM
> punch card installation in Germany for two years. After leaving the Army
> IBM hired me at their plant in Endicott, NY in 1960. My first job was as
> a final inspector for IBM 650s. It had hundreds of vacuum tubes and
> thousands of diodes. The storage device was a magnetic drum rotating at
> 12,500 rpm if I remember correctly.
>
> Over the next 34 years I worked with a variety of machines and projects
> ending up in Research Triangle Park, NC as one of the Architects in the
> System Network Architect (SNA) group. I was responsible for the
> maintenance of the architecture of Path Control.
>
>
>?
>
>
|
I thought I read that the new 003 firmware release fixed the CW pops.
73
Evan
AC9TU
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Hi George,
I have the same, swr meter is not working on this moment and I have also the popping sound when release the key or paddle.
These are firmware issues.
73's Jacques PA3EVZ
A couple of questions while trying out my new QMX. The S meter does not display when enabled. In CW mode when I release the key I get a significant popping sound in my earphones. Any suggestions? Thank you
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Re: QMX LTSpice BPF filter plots
That is excellent, Steve. Thank you for doing that.
I feel relieved as I may not be losing my mind after all. I will sleep well tonight.
Dan Tayloe offers a lot of valuable guidance here. May we all use it well!
Big 73 OM, KJ4A?
On Fri, Jul 14, 2023, 4:02 PM Steven Dick, K1RF < sbdick@...> wrote: Hi John and all. In an attempt to put this question to bed (Zin of
Tayloe detector), I emailed Dan Tayloe himself (the great and awesome Oz
? of the detector).? He got back to me today with a detailed response.?
Here's what he said:
"Yes, the impedance of the detector is open at zero beat and a short far
away. I look at the detector as a simple R/C lowpass filter where the R
is the input system impedance (which may be transformed by the receiver
input filtering).? Thus it is an ¡°integrating¡± detector where the
quadrature steered RF pulses are ¡°integrated¡± on the detector
capacitors.
The circuit you show is the original.? You can get the same effect by
feeding the RF inputs differentially using either a center tapped
transformer (the tap is for feeding the bias voltage for the switch,) or
a winding from a band pass filter and then only two output caps are
needed, 0 and 90 degrees.? I think the 4x output is simpler than a 2x
capacitor implementation and an input transformer.
In the desired passband, I consider it a high impedance.? However, the
impedance of the detector is also tied to the input impedance of the
audio preamplifier that follows the detector.? Ideally an
instrumentation amplifier would give a differential high impedance, but
those are expensive.? It is ¡°good enough¡± to use a normal low noise
op-tamp knowing that it is an unbalanced load? with the ¡°+¡± side being
high impedance and the ¡°-¡° side being low impedance.? Despite being
non-ideal, I have gotten very high sensitivity along with high blocking
and IP3 performance using this configuration and a 4 capacitor output.?
In that configuration two of the four detector caps see high impedance
and two see low impedance.? It is a mish-mash for sure, but the detector
is robust enough to perform well anyway even with is unbalanced load.
As noted the detector has a passband characteristic which helps reduce
the negative impact to large out-of-band signal, improving blocking and
third order distortion capabilities.? The other point to note is that
the detector only 0.9 dB of loss (using quadrature outputs) and much
lower drive requirements compared to 6 dB using a diode ring with its
corresponding high drive.
As far as RF filtering goes, the detector tends to reject the 2nd
harmonic, but that might be 40 or 50 dB down.? I don¡¯t remember for
sure, but the 3rd harmonic is only 9 dB down.? This at the very least
low pass filtering is needed on the front end to help further suppress
the 2nd harmonic and the 3rd harmonic.? I have seen some designs that
used the 3rd harmonic for the detection of the desired signal.
It has been rare, but I have heard SWBC AM breakthrough.? Thus a better
design would have a bandpass to help reduce strong SWBC out-of-band
signals.
Dan, N7VE
------ Original Message ------
From "John Z" <jdzbrozek@...>
To [email protected]
Date 7/14/2023 9:23:07 AM
Subject Re: [QRPLabs] QMX LTSpice BPF filter plots
>Yes, Steve.
>
>Your comments, along with my study of the Softrock Ensemble RX, and a
>little bit of LTSpice simulation have pretty well convinced me that
>your point of view is correct. The detector exhibits a very low input
>impedance. As I had mentioned earlier that was also my point of view
>before I tied myself in knots thinking too hard.
>
>JZ
>
>On Fri, Jul 14, 2023 at 9:13?AM Steven Dick, K1RF <sbdick@...> wrote:
>>
>>? John, It's a difficult subject and I appreciate all your thoughts on the topic.? But this last reply seems yo indicate the series LC bandpass filter sees a load impedance of 22-25 ohms, not high impedance as you previously discussed?
>>
>>? Thanks,
>>? Steve K1RF
>>
>>
>>? ------ Original Message ------
>>? From "John Z" <jdzbrozek@...>
>>? To [email protected]
>>? Date 7/14/2023 7:22:58 AM
>>? Subject Re: [QRPLabs] QMX LTSpice BPF filter plots
>>
>>? Alan,
>>
>>? I think those resistors serve multiple purposes:
>>
>>? ?Since the system bandwidth is controlled by the resistance in the capacitors charging path, having some stable, fixed resistance will bring more consistent bandwidth performance than if leaving it all to Rmux, Rbpf, etc.
>>
>>? ?Presumably the BPFs were designed with 50 ohm input and output impedance in mind. Adding the two resistors elevates the impedance on the secondary side of the 3-winding transformer. The primary side then appears to more suitably match the BPFs.
>>
>>? The receiver sensitivity and noise floor theoretically could be improved by eliminating those resistors, but my guess is that the gains would be imperceptible.
>>
>>? Contrasting to QDX and QMX, A selected LPF encounters on its way to the Tayloe detector, in order, a T/R switch transistor,
>>? a capacitor, a cap mux, an inductor,? a coil mux, a step up transformer and finally the detector itself.
>>
>>? What impedance does the LPF find itself terminated in? When the series LC is resonant there will be a string of FET channels present (T/R plus mux's... that's probably 20 ohms +/-) plus the impedance of the detector reflected lower by the trifilar transformer. So maybe 22-25 ohms in total. Not a match to a presumed 50 ohm LPF design point, but not so bad either.
>>? ...
>>
>>? Steve,
>>
>>? My concern has been both for the impedance seen by the Tayloe circuit and for the impedance the Tayloe places at the end of a BPF or LPF.
>>
>>? The NorCal 2030 design remains hugely puzzling to me as neither direction would appear to be satisfied.
>>
>>? JZ
>>
>>? On Fri, Jul 14, 2023, 6:45 AM Alan G4ZFQ <alan4alan@...> wrote:
>>>
>>>? On 14/07/2023 09:24, John Z wrote:
>>>? > a 10 ohm resistor in series with each of the two signal inputs.
>>>
>>>? I've been reading this but I'm not good enough to be certain about
>>>? impedances.
>>>
>>>? The above quote reminds me of a discussion about the purpose of these
>>>? resistors.
>>>? Some said it was to swamp out the low resistances of the mixer to even
>>>? out IQ balance.
>>>? Others suggested they should be removed, they reduce sensitivity.
>>>? Those comments obviously suppose a low impedance.
>>>
>>>? 73 Alan G4ZFQ
>>>
>>>
>>>
>>>
>>>
>>
>
>
>
>
>
|
After leaving MPLS Honeywell in 1960 I joined Control Data in a production division called IDP. I helped unload a truck full of stuff we purchased from the General Time division of a company located in Connecticut. It was a computer, had a compiler, concentrator and other perferals, I¡¯m old, can¡¯t remember everything. With a couple of exceptions, all tubes. The compiler had about 300. 6A37,s maybe? 12A37? We set up an assembly line. Got it to work and sold a system to the USPS. I Often think their still using it. Gary W0CKI?
toggle quoted message
Show quoted text
On Jul 14, 2023, at 1:50 PM, Dick Bingham <dick.bingham@...> wrote:
? That picture of a cordwood assembled module - tube included - took me back to 1965 memories.
It's been YEARS since I assembled cordwood modules for a Boeing prototype??Data Storage And Processor (DSAP) system for the USAF complete with a magnetic core memory.
As an aside, I had all of the Tech's (I was one of them) save? the diode lead clippings because they had a high Silver content. Someone eventually ended up with 10's-of-pounds of silver!
73? Dick/w7wkr at CN98pi Jim Campbell,
The attached image was scraped from the Hackaday web site. It is an
IBM flip-flop module using a dual triode vacuum tube. You probably saw
these in abundance in your sleep! I first encountered things like this
being sold at a surplus sales house called N. Silverstein's in
Detroit. As transistors and IC's obsoleted tons of old hardware, stuff
like this became available for parts, and for cheap. It helped to fuel
my early teen hobby days in the 1960's.
I went on to work at IBM in Lexington KY and designed chips for use in
electronic typewriter products. Many of our staff came from Endicott.
Later I found myself running the R&D operations for the Inkjet Printer
Division for IBM and later Lexmark.
Regards, JZ KJ4A
On Fri, Jul 14, 2023 at 1:27?PM Jim Campbell <jecspasc@...> wrote:
>
> The Army (ASA) sent me to IBM CE School after which I maintained an IBM
> punch card installation in Germany for two years. After leaving the Army
> IBM hired me at their plant in Endicott, NY in 1960. My first job was as
> a final inspector for IBM 650s. It had hundreds of vacuum tubes and
> thousands of diodes. The storage device was a magnetic drum rotating at
> 12,500 rpm if I remember correctly.
>
> Over the next 34 years I worked with a variety of machines and projects
> ending up in Research Triangle Park, NC as one of the Architects in the
> System Network Architect (SNA) group. I was responsible for the
> maintenance of the architecture of Path Control.
>
>
>
>
>
|
Fabulous, Dick!
I designed and assembled cordwood modules at GE Reentry Systems Division in Philadelphia in the early 1970's. They were op amp based integrators for capturing gamma rays reflected back from the burning nose cone of a space vehicle. The back scattered rays were captured by Cadmium Telluride detectors on re-entry to determine nose cone ablation properties. ?? Our government contract expired at the year end and so I spent New Years Eve in a basement lab at GE calibrating nose cone ablation models. I had to wear an exposure monitor.
The New Years Eve midnight subway ride back home from Center City out to Newtown Square PA was very memorable!
JZ
That picture of a cordwood assembled module - tube included - took me back to 1965 memories.
It's been YEARS since I assembled cordwood modules for a Boeing prototype??Data Storage And Processor (DSAP) system for the USAF complete with a magnetic core memory.
As an aside, I had all of the Tech's (I was one of them) save? the diode lead clippings because they had a high Silver content. Someone eventually ended up with 10's-of-pounds of silver!
73? Dick/w7wkr at CN98pi
Jim Campbell,
The attached image was scraped from the Hackaday web site. It is an
IBM flip-flop module using a dual triode vacuum tube. You probably saw
these in abundance in your sleep! I first encountered things like this
being sold at a surplus sales house called N. Silverstein's in
Detroit. As transistors and IC's obsoleted tons of old hardware, stuff
like this became available for parts, and for cheap. It helped to fuel
my early teen hobby days in the 1960's.
I went on to work at IBM in Lexington KY and designed chips for use in
electronic typewriter products. Many of our staff came from Endicott.
Later I found myself running the R&D operations for the Inkjet Printer
Division for IBM and later Lexmark.
Regards, JZ KJ4A
On Fri, Jul 14, 2023 at 1:27?PM Jim Campbell <jecspasc@...> wrote:
>
> The Army (ASA) sent me to IBM CE School after which I maintained an IBM
> punch card installation in Germany for two years. After leaving the Army
> IBM hired me at their plant in Endicott, NY in 1960. My first job was as
> a final inspector for IBM 650s. It had hundreds of vacuum tubes and
> thousands of diodes. The storage device was a magnetic drum rotating at
> 12,500 rpm if I remember correctly.
>
> Over the next 34 years I worked with a variety of machines and projects
> ending up in Research Triangle Park, NC as one of the Architects in the
> System Network Architect (SNA) group. I was responsible for the
> maintenance of the architecture of Path Control.
>
>
>
>
>
|
There is a page of parameters linked to the first option. I think it is the first. I am not at my QMX. Too nice at the beach. ;) There are two rows of numbers at the bottom of that screen. You have to go to the value you want to change and hit back space. Enter the new one and then use ctrl q to exit.?
--
Colin - K6JTH?
|
Thank you Mike and Colin for your kind and helpful responses. Mike, how do I access the band configuration? I don't see this on the menu options.
george/n9dxp
|
Re: QMX LTSpice BPF filter plots
Hi John and all. In an attempt to put this question to bed (Zin of Tayloe detector), I emailed Dan Tayloe himself (the great and awesome Oz of the detector). He got back to me today with a detailed response. Here's what he said:
"Yes, the impedance of the detector is open at zero beat and a short far away. I look at the detector as a simple R/C lowpass filter where the R is the input system impedance (which may be transformed by the receiver input filtering). Thus it is an ¡°integrating¡± detector where the quadrature steered RF pulses are ¡°integrated¡± on the detector capacitors.
The circuit you show is the original. You can get the same effect by feeding the RF inputs differentially using either a center tapped transformer (the tap is for feeding the bias voltage for the switch,) or a winding from a band pass filter and then only two output caps are needed, 0 and 90 degrees. I think the 4x output is simpler than a 2x capacitor implementation and an input transformer.
In the desired passband, I consider it a high impedance. However, the impedance of the detector is also tied to the input impedance of the audio preamplifier that follows the detector. Ideally an instrumentation amplifier would give a differential high impedance, but those are expensive. It is ¡°good enough¡± to use a normal low noise op-tamp knowing that it is an unbalanced load with the ¡°+¡± side being high impedance and the ¡°-¡° side being low impedance. Despite being non-ideal, I have gotten very high sensitivity along with high blocking and IP3 performance using this configuration and a 4 capacitor output. In that configuration two of the four detector caps see high impedance and two see low impedance. It is a mish-mash for sure, but the detector is robust enough to perform well anyway even with is unbalanced load.
As noted the detector has a passband characteristic which helps reduce the negative impact to large out-of-band signal, improving blocking and third order distortion capabilities. The other point to note is that the detector only 0.9 dB of loss (using quadrature outputs) and much lower drive requirements compared to 6 dB using a diode ring with its corresponding high drive.
As far as RF filtering goes, the detector tends to reject the 2nd harmonic, but that might be 40 or 50 dB down. I don¡¯t remember for sure, but the 3rd harmonic is only 9 dB down. This at the very least low pass filtering is needed on the front end to help further suppress the 2nd harmonic and the 3rd harmonic. I have seen some designs that used the 3rd harmonic for the detection of the desired signal.
It has been rare, but I have heard SWBC AM breakthrough. Thus a better design would have a bandpass to help reduce strong SWBC out-of-band signals.
Dan, N7VE
toggle quoted message
Show quoted text
------ Original Message ------ From "John Z" <jdzbrozek@...> To [email protected]Date 7/14/2023 9:23:07 AM Subject Re: [QRPLabs] QMX LTSpice BPF filter plots Yes, Steve.
Your comments, along with my study of the Softrock Ensemble RX, and a
little bit of LTSpice simulation have pretty well convinced me that
your point of view is correct. The detector exhibits a very low input
impedance. As I had mentioned earlier that was also my point of view
before I tied myself in knots thinking too hard.
JZ
On Fri, Jul 14, 2023 at 9:13?AM Steven Dick, K1RF <sbdick@...> wrote:
John, It's a difficult subject and I appreciate all your thoughts on the topic. But this last reply seems yo indicate the series LC bandpass filter sees a load impedance of 22-25 ohms, not high impedance as you previously discussed?
Thanks,
Steve K1RF
------ Original Message ------
From "John Z" <jdzbrozek@...>
To [email protected]
Date 7/14/2023 7:22:58 AM
Subject Re: [QRPLabs] QMX LTSpice BPF filter plots
Alan,
I think those resistors serve multiple purposes:
Since the system bandwidth is controlled by the resistance in the capacitors charging path, having some stable, fixed resistance will bring more consistent bandwidth performance than if leaving it all to Rmux, Rbpf, etc.
Presumably the BPFs were designed with 50 ohm input and output impedance in mind. Adding the two resistors elevates the impedance on the secondary side of the 3-winding transformer. The primary side then appears to more suitably match the BPFs.
The receiver sensitivity and noise floor theoretically could be improved by eliminating those resistors, but my guess is that the gains would be imperceptible.
Contrasting to QDX and QMX, A selected LPF encounters on its way to the Tayloe detector, in order, a T/R switch transistor,
a capacitor, a cap mux, an inductor, a coil mux, a step up transformer and finally the detector itself.
What impedance does the LPF find itself terminated in? When the series LC is resonant there will be a string of FET channels present (T/R plus mux's... that's probably 20 ohms +/-) plus the impedance of the detector reflected lower by the trifilar transformer. So maybe 22-25 ohms in total. Not a match to a presumed 50 ohm LPF design point, but not so bad either.
...
Steve,
My concern has been both for the impedance seen by the Tayloe circuit and for the impedance the Tayloe places at the end of a BPF or LPF.
The NorCal 2030 design remains hugely puzzling to me as neither direction would appear to be satisfied.
JZ
On Fri, Jul 14, 2023, 6:45 AM Alan G4ZFQ <alan4alan@...> wrote:
On 14/07/2023 09:24, John Z wrote:
> a 10 ohm resistor in series with each of the two signal inputs.
I've been reading this but I'm not good enough to be certain about
impedances.
The above quote reminds me of a discussion about the purpose of these
resistors.
Some said it was to swamp out the low resistances of the mixer to even
out IQ balance.
Others suggested they should be removed, they reduce sensitivity.
Those comments obviously suppose a low impedance.
73 Alan G4ZFQ
|
S meter probably not implemented yet. Firmware is very alpha.
Check band configuration Tx/Rx Parameter 2. If they are 0 change them
to 1 and that may take care of the popping.
-mike/w1mt
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Show quoted text
On Fri, Jul 14, 2023 at 3:44?PM George Carey <glcareyii@...> wrote:
A couple of questions while trying out my new QMX. The S meter does not display when enabled. In CW mode when I release the key I get a significant popping sound in my earphones. Any suggestions? Thank you
|
The S meter does not seem to be enabled in the FW yet. People have reported that disabling the battery meter solves the key click issue. We are using a very immature software right now. Soon we should graduate from alpha to beta releases.?
--
Colin - K6JTH?
|
George,?
There are a lot of QMX menu items that are non-functional. Some of them have just not been fully implemented and some are irrelevant as the QMX does a lot differently than the QCX and some things differently from the QDX. I suspect Hans simply ported over the menu systems from the QCX and QDX for simplicity and will sort all that out later.
--
73, Dan? NM3A
|
That picture of a cordwood assembled module - tube included - took me back to 1965 memories.
It's been YEARS since I assembled cordwood modules for a Boeing prototype??Data Storage And Processor (DSAP) system for the USAF complete with a magnetic core memory.
As an aside, I had all of the Tech's (I was one of them) save? the diode lead clippings because they had a high Silver content. Someone eventually ended up with 10's-of-pounds of silver!
73? Dick/w7wkr at CN98pi
Jim Campbell,
The attached image was scraped from the Hackaday web site. It is an
IBM flip-flop module using a dual triode vacuum tube. You probably saw
these in abundance in your sleep! I first encountered things like this
being sold at a surplus sales house called N. Silverstein's in
Detroit. As transistors and IC's obsoleted tons of old hardware, stuff
like this became available for parts, and for cheap. It helped to fuel
my early teen hobby days in the 1960's.
I went on to work at IBM in Lexington KY and designed chips for use in
electronic typewriter products. Many of our staff came from Endicott.
Later I found myself running the R&D operations for the Inkjet Printer
Division for IBM and later Lexmark.
Regards, JZ KJ4A
On Fri, Jul 14, 2023 at 1:27?PM Jim Campbell <jecspasc@...> wrote:
>
> The Army (ASA) sent me to IBM CE School after which I maintained an IBM
> punch card installation in Germany for two years. After leaving the Army
> IBM hired me at their plant in Endicott, NY in 1960. My first job was as
> a final inspector for IBM 650s. It had hundreds of vacuum tubes and
> thousands of diodes. The storage device was a magnetic drum rotating at
> 12,500 rpm if I remember correctly.
>
> Over the next 34 years I worked with a variety of machines and projects
> ending up in Research Triangle Park, NC as one of the Architects in the
> System Network Architect (SNA) group. I was responsible for the
> maintenance of the architecture of Path Control.
>
>
>
>
>
|
A couple of questions while trying out my new QMX. The S meter does not display when enabled. In CW mode when I release the key I get a significant popping sound in my earphones. Any suggestions? Thank you
|
Re: QMX help - damaged SMD capacitors
#problem
Here is the ending to this story. After my trouble ticket?WJG-P5N-NY9B going unanswered (25 days in queue today and still not even an acknowledgment of receipt), I sent my QMX to a professional electrical engineer who offered to help. The verdict came back as a dead CPU and thus no practical fix. I¡¯m not sure if the CPU was dead on arrival or if I inadvertently fried it while probing around trying to troubleshoot the original issue of the QMX not powering up.?
An expensive and disappointing outcome, but hopefully other novice builders will take some benefit from reading this and not have a similar outcome.?
|
Re: QMX Capacitor Swap Gives Lower Power.
#qmx
I wish it was that easy. Mine is already set at 30.
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Show quoted text
On Jul 14, 2023, at 13:34, Gary W9TD < w9td@...> wrote:
I also have better power output on 20 with the cap swap. I think your problem lies with the PIN diode bias. The band configuration screen that Hans showed for mod #2, shows only 5mA PIN bias on 20. That is wrong, it should be 30mA like all the other bands.
Gary
W9TD
|
Colin Kaminski
Dick Bingham