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Author Topic: Jay's continuing question thread...  (Read 1680 times)
WD0EGC
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Posts: 10




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« on: October 06, 2017, 04:41:34 AM »

I'm getting back into ham radio, after 30 years of inactivity.  My ARRL Amateur Radio Handbook was published in 1968, lol.  So, when I come up with a question that I can't readily find an answer for, I'll post them here:

#1.  What makes a power supply a "switching" power supply?  That was a term that didn't exist, back in the day. 

#2.  There are all sorts of newfangled Transceiver-Computer options that didn't exist, back when I was using my Tempo 2020 and HW-8.  Now, there are all sorts of digital modes, Ham Radio Deluxe, FT-8, SDR, controlling a rig remotely, and other terms I'm just beginning to understand.  What I can't figure out, when looking to buy a new or used transceiver....is it compatible with all of these new features? 

Thanks.
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KE4OH
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Posts: 131




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« Reply #1 on: October 06, 2017, 05:25:02 AM »

Welcome back! I was QRT for 33 years, so I know how it feels...

1. Well, switching power supplies did exist back then, they just weren't called that. Look in your old handbook and you will likely find DC to DC power supply designs that used transistors to provide pulsed DC ("switching") to get current to flow across a transformer. This in turn would jack up the ~12v (or whatever) supply voltage to the B+ needed.  Since then, the state of the art has advanced a bit, but the principles remain the same. Some bright people figured out that by using the same method (pulsing or switching) the supply voltage at a rate much higher than the standard household 60Hz, a very small transformer can be used to handle the same amount of current that would require a monster transformer at 60Hz.

So now we have a relatively cheap and lightweight power supply instead of one with a heavy (expen$ive) iron-core transformer.

Of course, today's switching supplies that hams use are stepping voltage down (120v to ~13v) to run solid state rigs vs. stepping voltage up to run the old tube gear back in the day.

2. Can't help you with this one. I only deal with cranky old tube gear from back in the day. All hot, all analog, all the time. Your former Tempo 2020 would be too modern for me.

73,

Steve KE4OH
« Last Edit: October 06, 2017, 05:29:14 AM by KE4OH » Logged

73 de Steve KE4OH
KQ4MM
Member

Posts: 19




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« Reply #2 on: October 06, 2017, 05:40:45 AM »

Welcome back Jay,


25 years QRT here before getting back in this past May.


Steve summed it up on the PS question. For the digital modes and rig control, you have lots of reading to do. Personally I read years worth of posts on eHAM and QRZ on the computer/digital topics, as well as all the reviews I could find on the current and most recent lineups of radios. Think of drinking from a fire hose.

Anyway, now having dipped my toes into the digital stuff and SSB OPs, I found myself re-learning CW and just enjoying that mode. Back in the day I only learned CW to pass the test so I basically had to start from scratch.

Good luck and I'm sure you'll get better answers from other more computer/ digital savvy OPs here.

73 KQ4MM

Brian

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KD3WB
Member

Posts: 91




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« Reply #3 on: October 06, 2017, 07:33:35 AM »

<snip>
#2.  There are all sorts of newfangled Transceiver-Computer options that didn't exist, back when I was using my Tempo 2020 and HW-8.  Now, there are all sorts of digital modes, Ham Radio Deluxe, FT-8, SDR, controlling a rig remotely, and other terms I'm just beginning to understand.  What I can't figure out, when looking to buy a new or used transceiver....is it compatible with all of these new features? 
Thanks.

Even the older rigs can be used for digital modes, they just need a different kind of
interface.  Newer rigs have built-in CAT control, which allows you to do other things, like
change the frequency using the computer.

https://www.google.com/search?complete=0&source=hp&q=ham+radio+computer+interface&oq=ham+radio+computer+interface

SDR is a technology that uses computer software to create and demodulate
radio signals instead of ordinary hardware

https://en.wikipedia.org/wiki/Software-defined_radio
http://www.websdr.org

Ben
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K6BRN
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Posts: 456




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« Reply #4 on: October 06, 2017, 01:02:14 PM »

Ben:

The term "SDR" is a popular misnomer.  No computer has the bandwidth/throughput needed to actually down-convert, demodulate and process an RF signal above a few tens of KHz.  Very little is done in software.

The more correct term is Digital Signal Processing (DSP) "radio"

In a DSP radio, the RF signal is digitized after the band-limit filter(s) and preamp, then sampled by an analog-to digital converter.  The sampled signal is usually passed to and ASIC (Application Specific Integrated Circuit) which performs digital filtering, downconversion and demodulation using a "dataflow" architecture (no CPU), completely in a number-crunching mathematical realm.  Alternately, a Field Programmable Gate Array (FPGA), which is a field configurable ASIC can be used at the cost of significant loss of efficiency, but reduced cost/risk for the developed part.  FPGAs are configured using a "Hardware Description Language" like VHDL or Verilog.  These languages do not generally support recursive functions common to "C" for example and are NOT classed as software by major commercial firms, in part because it takes a compiler and designer who is intimately familiar with the logic elements on the FPGA, how to connect them, how to manage clock domains and how to manage timing and I/O.

The reverse process is used for transmission, using a DAC instead of an ADC.

Often, amateur radio suppliers will use a low-IF or "baseband" CPU that really does run software to process the final 10 KHz or so of bandwidth.  But these processors are normally based on a Harvard Architecture (or similarly optimized DSP arrangement) that is very different than that of a PC's or controller's CPU.

I only bring this up because a very passionate gentlemen at HamCon West took the time to explain to me how he was going to design an direct sampling SDR using a small, popular and cheap controller CPU to perform all the processing.  Not going to happen.  But most people do not understand the distinction. 

Brian - K6BRN
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KS2G
Member

Posts: 732




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« Reply #5 on: October 06, 2017, 02:19:10 PM »

I'm getting back into ham radio, after 30 years of inactivity.  My ARRL Amateur Radio Handbook was published in 1968...

Rather than post numerous questions here, get the answers by updating your bookshelf:

ARRL Operating Manual 11th Edition
http://www.arrl.org/shop/ARRL-Operating-Manual-11th-Edition/
$24.95 plus shipping

ARRL Operating Manual 10th Edition
http://www.arrl.org/shop/ARRL-Operating-Manual-10th-Edition/
Closeout price: $19.95 plus shipping

ARRL Handbook 2018 (Softcover)
http://www.arrl.org/shop/ARRL-Handbook-2018-Softcover/
$49.95 plus shipping.
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KD3WB
Member

Posts: 91




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« Reply #6 on: October 06, 2017, 04:02:24 PM »

Ben:

The term "SDR" is a popular misnomer.  No computer has the bandwidth/throughput needed to actually down-convert, demodulate and process an RF signal above a few tens of KHz.  Very little is done in software.

The more correct term is Digital Signal Processing (DSP) "radio"

In a DSP radio, the RF signal is digitized after the band-limit filter(s) and preamp, then sampled by an analog-to digital converter.  The sampled signal is usually passed to and ASIC (Application Specific Integrated Circuit) which performs digital filtering, downconversion and demodulation using a "dataflow" architecture (no CPU), completely in a number-crunching mathematical realm.  Alternately, a Field Programmable Gate Array (FPGA), which is a field configurable ASIC can be used at the cost of significant loss of efficiency, but reduced cost/risk for the developed part.  FPGAs are configured using a "Hardware Description Language" like VHDL or Verilog.  These languages do not generally support recursive functions common to "C" for example and are NOT classed as software by major commercial firms, in part because it takes a compiler and designer who is intimately familiar with the logic elements on the FPGA, how to connect them, how to manage clock domains and how to manage timing and I/O.

The reverse process is used for transmission, using a DAC instead of an ADC.

Often, amateur radio suppliers will use a low-IF or "baseband" CPU that really does run software to process the final 10 KHz or so of bandwidth.  But these processors are normally based on a Harvard Architecture (or similarly optimized DSP arrangement) that is very different than that of a PC's or controller's CPU.

I only bring this up because a very passionate gentlemen at HamCon West took the time to explain to me how he was going to design an direct sampling SDR using a small, popular and cheap controller CPU to perform all the processing.  Not going to happen.  But most people do not understand the distinction. 

Brian - K6BRN

Thanks for the correction.

Ben
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K0UA
Member

Posts: 1362




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« Reply #7 on: October 07, 2017, 07:19:19 AM »

Power supplys have been covered.

Newer radios, will nearly all be compatible with new techniques/digital modes.   I have an IC 7300 made by Icom, which is a newer design of SDR in a box with knobs and switches. It is a joy to operate and use.  So easy to get set up on digital modes.  No external interfaces needed to hook to your computer, just a standard USB cable.  That USB stands for Universal Serial Bus, not Upper Side Band, by the way. Smiley.

  I would be happy to assist you getting set up on digital if you get a newer radio..  The tempo 2020 and the HW8, can be sidelined as backup rigs or fun rigs to tinker with.  But if you want to join the 21st century of hamdom, get yourself something a bit newer.  Rigs have came up considerably in capabilities, and have gone done in comparable price over the years, with the last couple of years making a tremendous impact.  I expect this trend to continue with more and more of the SDR units coming online.

Let me know if you need any assistance, just drop me an email (my email is good on QRZ.com) and we can hook up.  I often help people over the phone as long distance telephone calls are a thing of the past.

73, and good luck.  Look upon this new awakening as a big shiney new adventure.   James K0UA
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K8AXW
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Posts: 6312




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« Reply #8 on: October 07, 2017, 09:38:17 AM »

EGC:  I have what might be considered an "off the wall" suggestion.

After being off the air for 30 years, get back on with what you left  off with.  Forget this new stuff for a bit and get your feet wet once again and then as you have fun with your old and familiar "toys," investigate this new stuff. 

If I was to buy a new rig today, not being out of the game for 30 years, it would still take me a long time.... like weeks if not months, to decide what to buy and why.

For example, being 81 years old, I simply cannot tolerate these menu driven radios.  This means radios that does everything you want bit you have to push a button that provides a menu and in many cases, sub-menus to find the function you want or need.

2G made an excellent suggestion on updating your library and then what you don't understand, visit eHam and ask your questions.

Take your time OM and welcome back.


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K6AER
Member

Posts: 4670




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« Reply #9 on: October 07, 2017, 12:55:40 PM »

Buy a used IC-7200 for $600 and enjoy all the digital modes as well as the analog ones.

The antennas are still the same.

Bands are the same.

Your friends are 30 years older. You might have to shout.
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N0YXB
Member

Posts: 1121




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« Reply #10 on: October 07, 2017, 06:15:37 PM »


Your friends are 30 years older. You might have to shout.

What??  Smiley
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