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Re: Just Thinking??
AD7ZU
Curt,
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I couldn't agree more!? QCX has astounding performance / $? It is also great to see more amateurs designing, experimenting, and building. Randy AD7ZU On Wednesday, August 21, 2019, 6:59:22 PM MST, Curt via Groups.Io <wb8yyy@...> wrote:
Well certainly that's a path for an all band rig, but for a bit more than $49. Sometimes we need to marvel at the mix of technical with value. I imagine a lot more QCX rigs on the planet than KX2 rigs. My antennas aren't really big enough to he crunched even here in Maryland with many big kW stations, okay none are much closer than 10 miles. But of course I appreciate a decent front end. The k2 isn't bad, maybe I need to seek out comparative linearity of other rigs including the qcx. One can go overboard with front end linearity. Glad we've retained a sense of wonder here. I hope we haven't scared Bob away from bench. Maybe I will find my bench stuff again. 73 curt |
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Any interest in a TD-55 Tube Tester?
I found a Superior TD-55 Vacuum Tube Tester. It has a soft carrying case, manual, and cross reference list of tubes included. It appears to light up when plugged in, but I have no idea if it is working.
For sale if anybody wants it. I have no idea on price, but hopefully enough to cover shipping. Shipping from the US, Zip code 50219 (near Des Moines, IA) Thanks, David W0IM Link to picture of similar item: <> |
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Re: Just Thinking??
Bob Macklin
I received my NorCal Sierra parts from Germany today. Now I have the start
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for a NorCal Sierra and 3 NorCal 40 rigs. I recently went through the manuals for the NorCal 40, NorCal Sierra, Elecraft K1, Elecraft K2, and Elecraft K3. I could see the progression of the design.They are all built around the basic 4.915MHz crystal filter IF. My first one will be a NC40 with a DDS VFO. I'll also do the NC sierra with a DDS VFO. I have started wiring the DDS VFO. It has two serial ports that are optically isolated. One is for CAT, the other is for a keyer. It is designed to allow use of either an AD9850 or a SI5351. I will test both. I'm 85 now and I hope I can finish this project by the time I am 90. I can't afford a spectrum analyzer so I am planning on building one. Probably good to about 200MHz. I really do't need UHF and microwave capability. Bob Macklin K5MYJ Seattle, Wa. "Real Radios Glow In The Dark" ----- Original Message -----
From: "Curt via Groups.Io" <wb8yyy@...> To: <[email protected]> Sent: Wednesday, August 21, 2019 6:59 PM Subject: Re: [qrp-tech] Just Thinking?? Well certainly that's a path for an all band rig, but for a bit more than $49. Sometimes we need to marvel at the mix of technical with value. I imagine a lot more QCX rigs on the planet than KX2 rigs. My antennas aren't really big enough to he crunched even here in Maryland with many big kW stations, okay none are much closer than 10 miles. But of course I appreciate a decent front end. The k2 isn't bad, maybe I need to seek out comparative linearity of other rigs including the qcx. One can go overboard with front end linearity. Glad we've retained a sense of wonder here. I hope we haven't scared Bob away from bench. Maybe I will find my bench stuff again. 73 curt |
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Re: Just Thinking??
Well certainly that's a path for an all band rig, but for a bit more than $49. Sometimes we need to marvel at the mix of technical with value. I imagine a lot more QCX rigs on the planet than KX2 rigs.
My antennas aren't really big enough to he crunched even here in Maryland with many big kW stations, okay none are much closer than 10 miles. But of course I appreciate a decent front end. The k2 isn't bad, maybe I need to seek out comparative linearity of other rigs including the qcx. One can go overboard with front end linearity. Glad we've retained a sense of wonder here. I hope we haven't scared Bob away from bench. Maybe I will find my bench stuff again. 73 curt |
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Re: Just Thinking??
AD7ZU
Allison,
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as always,? enlightening commentary actually what I have been considering is to mod a ubitx to convert the 2nd IF to12Khzthen the remainder in DSP (final baseband frequency translation, phase shift, summing, filtering, AGC) All that fits in a single Analog Devices adau1761 codec internal DSP...ahhh no messy ADC to ucontroller to DAC interface timing stuff! use a single baseband mixer / sampling detector down conversion to 12Khz and ADC ala W7PUA's DSP 10 design (EMRFD)that way no quadrature LO, one baseband mixer/detector, one baseband amplifier, no hardware associated quadrature errors or DC offsets, no precision parts, and? no quadrature error trim required. the ADAU1761 has about 100db dynamic range.? Configure AD converters in mono for additional 6db of range. Selectable gain ahead of the ADC is in a single lane allows control of the ADC input. ADAU1761 even has a built in headphone amp. I haven't yet mapped possible/likely birdies... I will add that to the to-do list even a few more thoughts Randy AD7ZU On Wednesday, August 21, 2019, 10:04:46 AM MST, ajparent1/kb1gmx <kb1gmx@...> wrote:
Randy, IT also makes for a slew of birdies and lots of circuitry and maybe a needs for shielding. Since according to some you can make IQ phasing work perfect at only one frequency why not stop at? the first conversion you suggested 45mhz (or even 63) and then do the IO conversion there to audio. DSP simplifies the audio and can be made to have filters as well but to do it well you need a lot of bits in the ADC and a fair amount of processing speed.? Modern 32bit DSP chips do that but ADCs of less than 16bits limit dynamic range. Doing the processing at audio using linear parts (opamps) can easily get the needed performance and at far lower consumed power.? The dynamic range is limited only by the design details. Allison -- Please reply on the group, no private emails we as a group get to share info that way. |
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Re: Just Thinking??
ajparent1/kb1gmx
Randy,
IT also makes for a slew of birdies and lots of circuitry and maybe a needs for shielding. Since according to some you can make IQ phasing work perfect at only one frequency why not stop at the first conversion you suggested 45mhz (or even 63) and then do the IO conversion there to audio. DSP simplifies the audio and can be made to have filters as well but to do it well you need a lot of bits in the ADC and a fair amount of processing speed. Modern 32bit DSP chips do that but ADCs of less than 16bits limit dynamic range. Doing the processing at audio using linear parts (opamps) can easily get the needed performance and at far lower consumed power. The dynamic range is limited only by the design details. Allison -- Please reply on the group, no private emails we as a group get to share info that way. |
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Re: Just Thinking??
AD7ZU
Just a few more thoughts
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The dual mixer architecture of the current in vogue imagecancelling receiver architecture does have some downside.? The amplitude and phase errors accumulatefrom imbalance in the mixer or sampling detectors, the quadrature LO, and inthe analog phase shift networks.? The QCX?design generates a training signal atthe image frequency which is used to adjust the analog phase shift network tocompensate.? The image correction usingthat method is only ¡°perfect¡± at a single baseband frequency.? In a DSP version a second problem arises withthe DC offset near the beat frequency that is an artifact of both the A/Dconverters and the DSP Hilbert transform approximation that creates the 90degree phase shift at baseband but is not accurate near zero beat. ?An alternative design with better image rejection is a dualconversion first to a high IF say 45Mhz which is filtered with a relaxed crystalfilter then down converted by single mixer or sampling detector to a low IFthat is in range of the A/D, perhaps 12 Khz. The preselector filter need only below pass filter..say 30Mhz? permitting generalcoverage of 1.8Mhz to 30Mhz without having to select input filters and offers superbimage rejection. The low IF is then converted using a single A/D converter, the90 degree phase shift and sideband selection are very accurate, there is no DCoffset error and the frequency translation from 12Khz to final baseband is verysimple if the low IF is operated at 4x the final baseband: ?requires a multiplication of the I lanesamples by 0,1,0,-1 and 1,0, -1,0 in the Q lane to translate the 12Khz to the finalbaseband since the 12Khz is ? ?the 48Khz samplerate. The I and Q lanes are then accurately summed in DSP,? and the final audio bandpass filtering eitherSSB, or CW can then be performed at a lower processing rate. ?That design eliminates all sources of hardware error thatrequire compensation in either software or adjusting phase and amplitude errorsin the phase shift network or sampling detector. ¡.lots of advantages, BUT! theup conversion design does not make for a ¡°crunch proof¡± front end. Randy AD7ZU On Saturday, August 17, 2019, 7:32:14 PM MST, Curt via Groups.Io <wb8yyy@...> wrote:
Quadrature mixing to baseband is highly in vogue. The imprecision of the 90 degree mixing is corrected after a/d conversion by digital processing.? I am thinking the kx2 does this. The qcx in contrast using resistive tweaking to cancel its image. The built in routine to make this adjustment is amazing. 73 curt |
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Re: Alternatives to metal shear
Jim and all the main thing is that the tools used for scoring the aluminum
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needs to be sharp and hard. I have used old files and they seem to outlast any blades I have used in a utility knife. 72, Jimmy, W9JDH. On Tue, Aug 20, 2019, 4:24 PM Jim Burns <outbackerwb4ilp@...> wrote:
I wonder if the handheld scoring tools sold at home centers for use on |
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Re: COMMERCIAL:[qrp-tech] Online Sources of Old Data Books
There are some good books about radio technical stuff from the BBC engineering info page.
They have some good stuff on smith charts, propagation, antennas, sound, etc. There are also some older books to download, mostly in PDF. BBCeng.info Recollections of BBC engineering from 1922 to 1997 <> Thanks, David W0IM |
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Re: Alternatives to metal shear
I wonder if the handheld scoring tools sold at home centers for use on
plastic sheet would work on aluminum? I think I have one somewhere; if I find it I'll give it a try. Jim WB4ILP On 5:19PM, Tue, Aug 20, 2019 Jim Burns via Groups.Io <outbackerwb4ilp= [email protected] wrote: Hey Jimmy ! That should work. I'll give that a try. Many years ago I |
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Re: Alternatives to metal shear
Hey Jimmy ! That should work. I'll give that a try. Many years ago I
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received free samples of thin flat brass sheet that were shaped and scored so the flat sheets could be bent to form a 5 sided box that could be soldered on PCB's as RF shielding enclosures. Jim WB4ILP On 4:02PM, Tue, Aug 20, 2019 JD Hill <w9jdh.qrp@... wrote:
Jim, if you have a brake you can measure the size of the pieces you need, |
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Re: Alternatives to metal shear
Jim, if you have a brake you can measure the size of the pieces you need,
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then mark your pieces with a fine tipped Sharpie. You can then use a good straight edge and score the pieces with a good utility knife or a sharpened file. Score the pieces 3 or 4 times using quite a bit of pressure. Clamp the aluminum in the brake then bend the metal back and forth 3 or 4 times and it will normally snap off fairly smooth. I wouldn't use that method all the time but in a pinch it will work. 72, and safety first Jimmy,. W9JDH. On Tue, Aug 20, 2019, 8:03 AM Jim Burns <outbackerwb4ilp@...> wrote:
Is there a practical way to score thin aluminum sheet so it can simply be |
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Re: Online Sources of Old Data Books
My favorites and
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Fred W4JLE -----Original Message-----
From: [email protected] [mailto:[email protected]] On Behalf Of Peter Filiberti Sent: Tuesday, August 20, 2019 14:24 To: [email protected] Subject: [qrp-tech] Online Sources of Old Data Books I have found and downloaded some full pdf's of databooks from Motorola etc that I find occasionally on the web. This allows me to donate or recycle the space consuming book on the shelf. I honestly used to prefer the books and the older data book were full of wonderful technical information whereas today a lot of them just have the specifications of the component and possibly a few sample test circuits. In any case here is a site I found with some good pdf's on discrete components as well as some ic's you just may have in the parts drawer. Maybe if anyone has other links to this type of info we can share it on here so others can free themselves of the book storage. It's hard to let go... 73 |
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Online Sources of Old Data Books
I have found and downloaded some full pdf's of databooks from Motorola etc that I find occasionally on the web. This allows
me to donate or recycle the space consuming book on the shelf. I honestly used to prefer the books and the older data book were full of wonderful technical information whereas today a lot of them just have the specifications of the component and possibly a few sample test circuits. In any case here is a site I found with some good pdf's on discrete components as well as some ic's you just may have in the parts drawer. Maybe if anyone has other links to this type of info we can share it on here so others can free themselves of the book storage. It's hard to let go... 73 |
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Re: Alternatives to metal shear
Is there a practical way to score thin aluminum sheet so it can simply be
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bent and broken away? Jim WB4ILP On 4:53PM, Mon, Aug 19, 2019 Rolf Ekstrand <rekstrand@... wrote:
There is an old sheet metal trick for table saws (or hand saws) when it |
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Re: Alternatives to metal shear
Or you could always make one -
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On Sun, Aug 18, 2019 at 10:36 AM JD Hill <w9jdh.qrp@...> wrote:
I have access to a large industrial shear that I use to cut larger pieces |
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Re: Manual for OHR DD-1 needed.
I did. Nothing there.
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72 - n0hj On Mon, Aug 19, 2019 at 11:24 AM k6whp <k6whp@...> wrote:
Check your PM inbox. |
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