Re: An IF in search of a radio
"Ah, Grasshopper, It is good you asked this question." ( If you'll forgive a KungFu paraphrase.)
All the equations governing the time and frequency behavior of filters are well defined.
The experience is the IC-705. All the rest is 40 years of DSP in the oil industry and an active interest in low cost, high performance QRP CW rigs.
A bell is a narrow band resonator. A concrete block is a broadband resonator. Bell goes "bong......". Block goes "clunk".
This is intrinsic to the mathematical relationship between time and frequency. For most of my life I thought that was the end of the story. And I worked at the reflection seismology research level. I could have made a *killing* if I'f figured this out. But so far as I know, no one in the community that invented DSP thought of it.
The fundamentals are simple.
The time domain response of a filter is dependent upon the width of the filter, not the input signal. If you output from the first filter a segment that only has 50 Hz of overlap with the 2nd filter yo will get a 50 Hz filter without any ringing. It's very fundamental and I am embarrassed neither I nor, to my knowledge, any of my coworkers thought of doing it.
Have Fun!
Reg
On Friday, May 12, 2023, 05:34:30 PM CDT, Daniel Ricardo Perez LW1ECP via groups.io <danyperez1@...> wrote:
Hi! I am puzzled about the fact that using 2 cascaded, overlapping filters results in less ringing than a single CW filter with same resulting bandwidth. Have you experienced that or is it a guess?
I suppose a good RF simulator could give an idea of the results making a time domain simulation.
BTW, I don't think 5.0 MHz is a particular option, one doesn't need having WWV accuracy to align a filter, in special a shiftable filter. 9 or 10MHz should be easier to shift because the percent change is smaller.
Have success!
Daniel Perez LW1ECP
El viernes, 12 de mayo de 2023 19:19:23 ART, Reginald Beardsley via groups.io <pulaskite@...> escribi¨®:
I recently bought an Icom 705 and have been stunned by the performance of twin tunable pass band filters.? I want to duplicate that using analog filters.? As it happens, 5 MHz HC-49/S crystals are less than a dime with other frequencies available at similar prices.? But 5 MHz provides some interesting options in radio design.? Particularly in the self diagnose and repair department.
Key concepts:
a 5 MHz IF allows using WWV for very precise calibration and alignment in conjunction with a noise source
the required frequency shifts are very small relative to Fp & Fs
varactors should easily perform the shifts
a nanoVNA will measure the xtal to provide the values needed to match that xtal
a program will calculate the optimal choice of xtals and capacitors & varactors from small pools (10-20) of parts to meet design goals with manual trimming as needed.? ? A pair of 4 pole? varactor tuned filters shouldn't be that hard.
Why go to all the problem of matching filters only to have a fixed frequency filter?? Worst case use a latching DAC and MSP430 to set the varactors.? All a question of current drain.
Have Fun!
Reg
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Re: An IF in search of a radio
Hi! I am puzzled about the fact that using 2 cascaded, overlapping filters results in less ringing than a single CW filter with same resulting bandwidth. Have you experienced that or is it a guess?
I suppose a good RF simulator could give an idea of the results making a time domain simulation.
BTW, I don't think 5.0 MHz is a particular option, one doesn't need having WWV accuracy to align a filter, in special a shiftable filter. 9 or 10MHz should be easier to shift because the percent change is smaller.
Have success!
Daniel Perez LW1ECP
El viernes, 12 de mayo de 2023 19:19:23 ART, Reginald Beardsley via groups.io <pulaskite@...> escribi¨®:
I recently bought an Icom 705 and have been stunned by the performance of twin tunable pass band filters.? I want to duplicate that using analog filters.? As it happens, 5 MHz HC-49/S crystals are less than a dime with other frequencies available at similar prices.? But 5 MHz provides some interesting options in radio design.? Particularly in the self diagnose and repair department.
Key concepts:
a 5 MHz IF allows using WWV for very precise calibration and alignment in conjunction with a noise source
the required frequency shifts are very small relative to Fp & Fs
varactors should easily perform the shifts
a nanoVNA will measure the xtal to provide the values needed to match that xtal
a program will calculate the optimal choice of xtals and capacitors & varactors from small pools (10-20) of parts to meet design goals with manual trimming as needed.? ? A pair of 4 pole? varactor tuned filters shouldn't be that hard.
Why go to all the problem of matching filters only to have a fixed frequency filter?? Worst case use a latching DAC and MSP430 to set the varactors.? All a question of current drain.
Have Fun!
Reg
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An IF in search of a radio
I recently bought an Icom 705 and have been stunned by the performance of twin tunable pass band filters. I want to duplicate that using analog filters. As it happens, 5 MHz HC-49/S crystals are less than a dime with other frequencies available at similar prices. But 5 MHz provides some interesting options in radio design. Particularly in the self diagnose and repair department.
Key concepts:
a 5 MHz IF allows using WWV for very precise calibration and alignment in conjunction with a noise source
the required frequency shifts are very small relative to Fp & Fs
varactors should easily perform the shifts
a nanoVNA will measure the xtal to provide the values needed to match that xtal
a program will calculate the optimal choice of xtals and capacitors & varactors from small pools (10-20) of parts to meet design goals with manual trimming as needed. A pair of 4 pole varactor tuned filters shouldn't be that hard.
Why go to all the problem of matching filters only to have a fixed frequency filter? Worst case use a latching DAC and MSP430 to set the varactors. All a question of current drain.
Have Fun!
Reg
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Re: Ebay HamGeek iambic paddle find
That's cruel ;-)
On Friday, April 14, 2023, 09:26:26 AM CDT, Froggie the Gremlin <jonpaul@...> wrote:
In Paris found a French made Vibroplex circa 1950s..1960 NIB, paid €5!
Jon
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Re: Ebay HamGeek iambic paddle find
In Paris found a French made Vibroplex circa 1950s..1960 NIB, paid €5!
Jon
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Ebay HamGeek iambic paddle find
I bought an Icopm 705 a few weeks ago and it has me very eager to get re-licensed. I was looking for a Vibroplex Code Warrior Jr. but couldn't find one in stock, so I waded through the ebay listings and found these.
I bought one to use with my Icom 705 and liked it enough to buy a 2nd one to tinker with. I'm going to replace the ground contact hex spacer with a piece of .999 silver bar, make silver caps for the contact screws and replace the hex insulators with rectangular bars with a hole to access the magnet mounting hole so I can adjust the position a la CWJ and switch to using a spring if I don't like the magnets.
The second paddle arrive along with 4 of the 5 magnets I ordered. I measured them with a Gauss meter and installed the strongest one. The 5th one should be stronger, but this is quite usable. With some minor changes I can switch to using a spring. The vertical members are simple hex spacers and insulators tapped M3-0.5, so easy to make nicer supports.
Happily, the key fits in the box long with the cable. This is my first iambic paddle, but so far I have no complaints. After a few days practice I can produce run 15 wpm with few errors in timing. I'm wathcing the do-dash space using the 706 audio scope feature while I wait for my Morserino to show up.
I'll make a paddle from scratch is this comes up short. For a portable paddle I can't see how you can beat it. It has ball bearings.
The photos are in reverse order from finished result to start. There is a metal slot in the base that the zip ties fasten the cable to.The blue plate in 2834 is a self stick steel plate you can use to mount the key to a non-ferrous object.
The only keys I found under $110 were all mostly plastic, some 3D printed and at prices that were not attractive.
Have Fun!
Reg
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MS5351M as a substitute for Si5351A
Hi all
QRP Labs kits are heavily dependent on the Si5351A from SiLabs. Sadly?this chip is a victim of the ongoing global semiconductor shortage, and perhaps also the acquisition by SkyLabs, of parts of Si5351A business including the clock generator ICs.?
At the same time there is a new substitute chip MS5351M which has good availability, and has been recommended by several correspondents; I am also aware of some kit vendors already using the MS5351M in their products. Clearly it "works". However, the MS5351M documentation is very sparse and I have not seen any actual performance measurements or comparisons documented. To gain enough confidence to be able to start using this chip I undertook as many detailed measurements as I could, including phase noise measurements and use in QCX-mini CW transceivers, and documented them here:
The conclusion is that the MS5351M is a 100% direct substitution for Si5351A and has slightly improved performance in some areas. In my opinion, MS5351M can be used in place of Si5351A in any hobby project or commercial product.?
Due to my substantial former purchases as the global semiconductor shortage was getting underway, I still have a stock of around 1,000 Si5351A ICs but it is inevitable that going forward, in order to continue production of QRP Labs kits, we will start to use the MS5351M in some manufacturing batches.?
Much as I dislike cross-posting normally, I am cross-posting this one to other QRP discussion groups in the hope that the measurements may be of interest to some. Many of us use the Si5351A in our hobby projects and some of us in our commercial products too. This is previously unpublished information that I have not seen anywhere else.
73 Hans G0UPL
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Re: OT IEEE Spectrum article cipher machine spy case
My interest in codes started when I was in high school, even wrote an article for the local paper.
Your article was awesome, very clear descriptions, many useful photos and insights.
Thank you!
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Re: OT IEEE Spectrum article cipher machine spy case
Fascinating article-and very fine photos, too.? I couldn't stop reading.?
Dave?
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On 2021-08-31 14:06, Froggie the Gremlin wrote:
Hello all: My IEEE Spectrum article about a 1963 cipher machine and a huge espionage case Rubicon just went online
about a years work. Last photo has some HP and TEK equipment.
Your thoughts appreciated!
Jon
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Re: OT IEEE Spectrum article cipher machine spy case
Jon,
Many thanks, that is very cool! I was enthralled by crypto in my teens. The central repository librarians for the state of Arkansas got me a used copy of "Secret and Urgent" which I coveted because it had frequency tables in the back (including trigrams! ;-)
Have Fun!
Reg
On Tuesday, August 31, 2021, 04:06:56 PM CDT, Froggie the Gremlin <jonpaul@...> wrote:
Hello all: My IEEE Spectrum article about a 1963 cipher machine and a huge espionage case Rubicon just went online
about a yers work. Last photo has some HP and TEK equipment.
Your thoughts appreciated!
Jon
|
OT IEEE Spectrum article cipher machine spy case
Hello all: My IEEE Spectrum article about a 1963 cipher machine and a huge espionage case Rubicon just went online
about a yers work. Last photo has some HP and TEK equipment.
Your thoughts appreciated!
Jon
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Re: Low cost/Field Day HF test bench concept
I'm looking at this as an EM support function. First responders depend on radios. And we have all seen many trivial repairs that required significant diagnostic tools but took no time to execute. Certainly, for typical Field Day ops a DMM and antenna analyzer are pretty much it. Though TDR would be useful.
After dragging my feet for many years, I finally bought a very fine suite of HP and Tek kit. Then the nanoVNA and tinySA appeared. So the "Field Day Bench" is just rationalization of new toys.
I'm not currently licensed. I have been twice as a novice, but let the 2nd one lapse because I couldn't afford a radio or the T&M kit to build one.
My primary interest is the technology. I find it truly magical. Doing basic undergrad level RF design was previously impossible on ones own without T&M access. Owning the kit was unthinkable. Now it's a reasonable investment in acquiring skills.
Have Fun!
Reg
On Thursday, July 22, 2021, 05:02:13 PM CDT, Peter Ayearst <ve3poa@...> wrote:
Hi Reg,
That's quite a list. For Field day I figured a dmm and an antenna analyzer was about all I would need. If I needed more test gear to get my setup going for FD I'd turn to socializing. :)
Having said that,? as my homebrew career developed,? there were a couple of test gear that I bought that was like turning the lights on.
The scope was the 1st? major piece of gear that opened the world of rf and immediately became indispensable. A good signal generator was a welcome addition but things really opened up when I purchased a Spectrum Analyzer.?
Being able to measure things made the hb experience even more enjoyable.? Couldn't do without the scope or SA? now.
Next challenge was to develop good measurement techniques and be able to interpret properly.?
Lots of fun.
73, Peter?
ve3poa?
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Re: Low cost/Field Day HF test bench concept
Hi Reg,
That's quite a list. For Field day I figured a dmm and an antenna analyzer was about all I would need. If I needed more test gear to get my setup going for FD I'd turn to socializing. :)
Having said that,? as my homebrew career developed,? there were a couple of test gear that I bought that was like turning the lights on.
The scope was the 1st? major piece of gear that opened the world of rf and immediately became indispensable. A good signal generator was a welcome addition but things really opened up when I purchased a Spectrum Analyzer.?
Being able to measure things made the hb experience even more enjoyable.? Couldn't do without the scope or SA? now.
Next challenge was to develop good measurement techniques and be able to interpret properly.?
Lots of fun.
73, Peter?
ve3poa?
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Low cost/Field Day HF test bench concept
I'm assembling the following suite of test kit just to see what it can do for radio design work. After evaluating the performance relative to my mid 90's HP & Tek kit, I plan to use this kit to do various exercises such as design an amplifier, oscillator, filter, etc and measure the performance.
For most of my life my RF ambitions were stymied by the lack of access to test gear. So for me, the nanoVNA and tinySA are huge. I have decided to make a project of building out the most complete, lowest cost Field Day portable HF test bench I can come up with.
The objective is coverage up to 222 MHz with sufficient accuracy and resolution to make experimental design more tractable.
Hantek 2D42 (DSO-DMM-AWG)
3x tinySA (SA and 2x RF synthesizers)
nanoVNA
RFzero (GPSDO)
LCR/transistor tester (need USB unit)
DMMCheck Plus (DMM cal)
Bodnar's pulser w/ 1 MHz repetition rate (TDR)
diode noise source
2x step attenuators
2x RF bridges
2x wide range matching networks
dedicated netbook to control above
cables, adapters, cal kits, etc
battery powered lab PSU
The Hantek is a compromise chosen because it provided 3 functions, was small, cheap and with a claim of 40 MHz BW appears good enough to me. There are possibly better options at the same price point, but they are much larger which is not meet the Field Day portability constraint..
With some care in shopping, the above should be available for under $1000. Despite my grad student slave wages 30 years ago, I'd have bought all that for $1000 in a heartbeat. And $1000 then would be much more today. All I can say is "Wow!"
Don't just sit there, say something! I did *not* start this to hear myself. The wall already serves that function ;-)
Have Fun!
Reg
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Re: Control feed thru connector suggestions?
I don¡¯t understand why, but feedthru caps have gone way up.
On Jul 17, 2021, at 1:42 PM, Reginald Beardsley via groups.io <pulaskite@...> wrote:
I have a bunch of RF eval boards from China which I want to connectorize in shielded enclosures. ??I don't want to spend $20 packaging a $8-15 board.
I make the enclosures from scrap 28 gauge galvanized steel scrap from a local HVAC shop. ?Quarter inch copper foil tape on the seams soldered to the zinc plating provides an RF tight seal.
For power connectors I've standardized on ?2.1 mm coaxial power sockets. ?All Electronics has them for under $0.20 so I bought 100. ?For prototyping I epoxy them to SS FR4and use copper foil on the epoxy side for pads and microstrip. ?This works great for Manhattan style construction. ?Even a small amount of epxoy goes a long way, so I make them up in batches ?of various size boards that use up all the epoxy I've mixed.
For obvious reasons I don't want to use the same connector for control lines. ?I'd like to find a cheap option for feed thrus. ?Ideal would be the connectors HP used in the 8601A, but I've never seen those for sale anywhere.
Does anyone have suggestions?
Have Fun!
Reg
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Re: Control feed thru connector suggestions?
Somehow it didn't register they were $1 each, not $4. I just ordered 40.
Reg
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Re: Control feed thru connector suggestions?
Dave,
Thank you!
That's exactly what I want. Don't like the price though. However, it's less than what I've found in my searches which were not what I wanted anyway. NOS HV was all I found in my searches.
I have a number of Chinese LNAs and such which use a similar connector so I know they make them. Don't understand why they are so hard to find.
Somewhat off topic, but I've been testing ebay RF bridges marked 60dBm.com (Ukraine) and transverters.store.com (China).
The 60dBm product is pretty duff despite looking very nice. The transvertes-store units didn't even have the ferrites glued down. So I flowed superglue under them.
But the Chinese unit is flat from <100kHz to 2.9 GHz to <1 dB and the ringing present looks like cable mismatch. After a quick numerical check it appears that it's reflections at the N connectors of the N-SMA jumpers I'm using. The actual drop off is about 0.5 dB. Rather remarkable for a <$12 item.
The Ukrainian unit rolls off very steeply below 1-2 MHz and rolls off 8.8 dB from 10 MHz to 2.9 GHz. When I tried to look at the transfer function with my 11801/SD-24 there was no transmitted fundamental in the 200 kHZ calibrator output.
This is just the start of characterizing them and a bunch of other passive RF modules.
Have Fun!
Reg
On Sunday, July 18, 2021, 02:30:19 PM CDT, DaveH52 <ac2gl.dave@...> wrote:
Maybe something like this:
https://www.mpja.com/Pack-of-4-Capacitor-Feedthru-1000pF/productinfo/36701+CF/
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Re: Control feed thru connector suggestions?
Maybe something like this:
https://www.mpja.com/Pack-of-4-Capacitor-Feedthru-1000pF/productinfo/36701+CF/
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Control feed thru connector suggestions?
I have a bunch of RF eval boards from China which I want to connectorize in shielded enclosures. I don't want to spend $20 packaging a $8-15 board.
I make the enclosures from scrap 28 gauge galvanized steel scrap from a local HVAC shop. Quarter inch copper foil tape on the seams soldered to the zinc plating provides an RF tight seal.
For power connectors I've standardized on 2.1 mm coaxial power sockets. All Electronics has them for under $0.20 so I bought 100. For prototyping I epoxy them to SS FR4and use copper foil on the epoxy side for pads and microstrip. This works great for Manhattan style construction. Even a small amount of epxoy goes a long way, so I make them up in batches of various size boards that use up all the epoxy I've mixed.
For obvious reasons I don't want to use the same connector for control lines. I'd like to find a cheap option for feed thrus. Ideal would be the connectors HP used in the 8601A, but I've never seen those for sale anywhere.
Does anyone have suggestions?
Have Fun!
Reg
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Re: July/August lead article in QEX
I just received my copy of the July/August issue of QEX and can now take a look at the article.
DaveD
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On 7/7/2021 12:56 PM, Reginald Beardsley via groups.io wrote: I'm curious what others think of this article. I have read it a few times and find it completely incomprehensible to the point I question the correctness. In particular, figures 9 and 13 are very hard to square with the central notion of a class C amplifier that it is in cutoff for more than 180 degrees. If the BE junction is in cutoff, then I'd expect the input current to be a periodic impulse, not the visually perfect sinusoids of figure 9A. Most troubling of all is figure 13A which purports to show the input current swinging between -58 mA and 89 mA. Where's the cutoff?
I'm a retired geophysicist, not an EE. I started playing with RF over 50 years ago, but couldn't afford the T&M kit to do serious work. I'm playing RF hardball for the first time using "RF Circuit Design" by Chris Bowick among numerous other books. Bowick has the clearest design procedures I've found. So far I've designed and built CC and CE small signal amplifier examples with CB next in the queue before moving on to power amplifiers.
The Spice implementations I've tried have resisted my efforts. Thus I have relied on the methods Bowik describes and measurements. But my goal is to compare design specification, simulation and measured data for each amplifier example.
Have Fun!
Reg
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Daniel Ricardo Perez LW1ECP
Froggie the Gremlin
DaveH52