"Bruce Varley"
** The topic is " ham radio" - Bruce.What I said was that hams are not using HF like they once used did - the tiny bits they own are barely used.
Get a communications receiver and you will see what sort of garbage the band is really full of - mainly data transmissions that sound like buzz saws.
... Phil
On 21/04/13 10.38, Jan Panteltje wrote: ... > Old school: If you were lucky you had a grid-dip meter to test LC circuits, > I once tried building one, it worked in some range, but was more work then use... ...
Hi Jan
It is because you need a digital dip meter. Analog display fiddling sucks. (just joking!) ;-)
I think he has found a smart way by simply exchanging the whole oscillator to change bands. He simply "route" higher bands signals to the prescaler - and bypass the prescaler, when measuring the lower bands.
Digital Dip Meter:
Schematic:
The above is a very crude and cheap digital spectrum analyzer with builtin frequency counter.
MB501 ought to exchanged with what you can get cheaper. Maybe some source code need to be changed:
Other analog dip meters:
A Dip Meter Using the Lambda Negative Resistance Circuit:
German: FET-Dip-Meter Mk2 (2*dual gate MOSFET):
Glenn
(Answer is send to sci.electronics.design )
Hi Bruce
They have not been abandoned. They just have heavy competition from PCs... The competition also happened to model railway, football, and other indoor and outdoor activities.
-The bands are stil used - especially 80 and 40 meters - but it also depends on the time of day and the sun spot cycle:
Listen for yourself. Press "View: all bands". Move the/click filter cursor to the frequency you wan't to listen to. Drag the skirts to get a wider/narrower filter. The waterfall tells tell the band story ;-) This is point and click receiving!:
Uses Java and Javascript:
WebSDR de W4AX:
WebSDR at K7UEB Walla Walla University Club Station:
Can use HTML5 instead of Java: Wide-band WebSDR:
(found via
Maybe Phil just want the bands for himself ;-) (just joking).
The public longwave, middlewave and shortwave stations have declined heavily the last - let say 10..15 years - because of radio by the internet I think.
The station as a function of time, can be found here for free:
ilgradio.com: This is the International Listening Guide:
There has been a movement toward digital (including stereo) public longwave, middlewave and shortwave stations instead of AM, but the receivers that support DRM are hard to find - there are only a few DRM stations (case of chicken and egg problem?):
But you can use your PC and its soundcard to demodulate DRM (SDR!) - on Windows, Mac OS X and Linux. You simply mixes the 455KHz IF down to two signals spanning approx. 0..12KHz called I(for inband signal; real part) and optionally Q(for quadrature signal; imaginary part):
DRM - Digital Radio Mondiale:
Glenn
On a sunny day (Sun, 21 Apr 2013 13:27:35 +0200) it happened Glenn wrote in :
That is very nice, clever idea, I have bookmarked that. Did you see my simple RS232 frequency counter?
That is not a simple circuit, looks like a symmetrical oscillator with 2 summed level detectors...
An excellent goal. The more people on a project who understand more than just their specialty, the less falls through the cracks between specialties, and the better things go.
Spectrum analyzers are pretty cool gizmos, and if you don't mind boat anchors, you can get amazingly good ones for reasonably cheap. I paid $1400 for my HP 8568B three or four years ago, and they've come down since then. That's quite a few restaurant lunches, but it's about the same as you'd pay for a good used oscilloscope in the 500 MHz or 1 GHz class, and you can do stuff with a SA that are very difficult otherwise.
There's a lot of overlap between radio and DSP. If you explore the connections between continuous-time and discrete-time Fourier analysis, you'll find that the notions of signal-to-noise ratio and all the useful theorems are either identical or closely analogous in the two domains.
This is a really amazing time for buying second-hand equipment. Since starting my consulting business about 4 years ago, I've furnished an entire electrooptical laboratory for about $30k, which is about three or four cents on the dollar. (I paid about 6% of new for a Tek TDS 694c last year, and that dragged up the average a bit--previously it was just about exactly three cents.) You can see the list at
Cheers
Phil Hobbs
(PS: Don't take Phil A. too seriously--he's an audio guy who knows his stuff, but he's also mentally unstable and becomes nasty when he's off his meds, which apparently he is at the moment. You can learn a lot from him about audio, but nothing about how to behave, whether on Usenet or anywhere else.)
-- Dr Philip C D Hobbs Principal Consultant ElectroOptical Innovations LLC Optics, Electro-optics, Photonics, Analog Electronics 160 North State Road #203 Briarcliff Manor NY 10510 USA +1 845 480 2058 hobbs at electrooptical dot net http://electrooptical.net
the crystal radio). I plan to start my experimentation first on the AM and FM broadcast bands and then move to the amateur bands once I get my license, so I initially won't go much higher than about 100 MHz.
intermittent access to a 1 GHz scope at work. Would that be enough for circuit verification?
analyzer (presumably from ebay)? I had read somewhere that even with low frequency stuff my oscillators or mixers could be giving out spurious oscillations at several GHz that I should be aware of.
and I wonder if those would be adequate for this kind of experimenting.
have very little experience with radio and so I expect there could be plenty of things going wrong spectrum-wise.
At your entry level what you need to do is not design receivers or transmitters, accept maybe a little tiny bug type, is to get a radio kit receiver and follow the instructions. There are many of them out there and they work just fine for people like you.
Read fully the operation details and theory of the design to get a full understanding of it.
As for getting a Ham license, you must remember that HAM operators and electronic design isn't quite the same. Although there are many that actually started with design work and then at some point got a license.
I was in design work for years before I even became a ticketed operator. I had/have friends that I assisted in getting their advanced & extra license for the theory part but never had a ticket myself. I just didn't seem to have the time to sit and just gab on the radio! I was more interested in talking about the movement of electrons.
P.S.
One day we had some clients visit our place and when they got to my mid evil work center, they were amazed at all the instrumentation I had lit up on the bench.. One of them asked me exactly what job I did, and I thought it was kind of obvious with all that was taking place on the bench but evidently it wasn't. So I told them I was an Electronologist.
Jamie
I have a 1Ghz service monitor that works very nicely at home base. It has all the usual things needed for a service monitor, along with a microphone to allow you to modulate on that ever freq you wish. Of course the output level isn't must to speak of and I didn't get it for that anyway..
I do have a small problem with it that I have only looked at once and didn't find anything obviously wrong at first glance. This think is hard to work on because you can't get at the boards very easy to do live testing, you have to clip leads on specific locations and put the board back in. I am sure the service center for these units had break out extension boards to solve that. The problem being is the horizontal sweep isn't as wide as it should be. This just happen one day when I turned it on. It all works and all, I just have to make up for the differences in calculations. THe testing of the HV and sweep board didn't yield any obvious problem. This thing is full of RCA op-am can chips.
Jamie
the crystal radio). I plan to start my experimentation first on the AM and FM broadcast bands and then move to the amateur bands once I get my license, so I initially won't go much higher than about 100 MHz.
intermittent access to a 1 GHz scope at work. Would that be enough for circuit verification?
analyzer (presumably from ebay)? I had read somewhere that even with low frequency stuff my oscillators or mixers could be giving out spurious oscillations at several GHz that I should be aware of.
and I wonder if those would be adequate for this kind of experimenting.
have very little experience with radio and so I expect there could be plenty of things going wrong spectrum-wise.
It seems that you're in need for basic information about building radios. Please get and read the ARRL handbook. It answers to most of your questions, and many more not arrived yet.
-- Tauno Voipio, OH2UG (for over a half century)
I just won three Fluke 8920A True RMS voltmeters for $20 on Ebay. One works. The second looks to be repairable. The third looks like it was hit by lightning with shorted power rails & missing signal traces.
There was some great stuff - radar, military, Collins, Hammarlund - that was developed without modern test equipment.
This would be a cool app: an internet based shortwave receiver. Locate a couple dozen antannas around the world, digitizing the entire spectrum from audio to 50 MHz maybe. Make the data available in real time.
-- John Larkin Highland Technology Inc www.highlandtechnology.com jlarkin at highlandtechnology dot com Precision electronic instrumentation Picosecond-resolution Digital Delay and Pulse generators Custom timing and laser controllers Photonics and fiberoptic TTL data links VME analog, thermocouple, LVDT, synchro, tachometer Multichannel arbitrary waveform generators
ly
I thought I got some encouragement from you early in the thread but now tha t's a complete let down :)
all
Yes, but I'm not interested much in getting on-Air (at least for now) and t alking to other hams with zero drift and 120 dBc phase noise (Ok I'm making up stuff from memory here) as much as I'm interested in learning theory an d having fun building things and tweaking them to become better.
In the 1970's, I kept several technicians busy helping design and build mostly marine radios. During the day, we would use the most modern technology and equipment of the time to work on the company products. After hours, the techs would work on their own ham and CAP radios. Oddly, they would not use all the modern test equipment, but preferred to revert to the stone age of radio and tune for maximum brightness on a light bulb dummy load. I see much the same thing locally among the enthusiasts. Either people tend to use whatever technology they're comfortable using, or the stone age is still with us today.
50There are SDR (software defined radio) receivers that will digitize various bandwidths depending on computing power. I don't have much experience with the technology. There are some PC sound card based systems that will digitize and record about 40KHz worth of HF spectrum. When played back, you can tune across the digitized band, and listen to each station individually, just as if it were in real time.
I've worked on diversity HF reception systems in the past that use geographically separated sites. This was before the internet, so leased analog lines were the fashion. I don't recall all the problems, but basically it didn't work. We could measure the SNR and switch receivers to whichever had the best signal, but even that was difficult on HF. Combining the signal at audio was possible, but the net SNR was about the same as a single receiver. Digitizing the entire mess would not improve things. Still, it's a cool idea, probably fun to play with, but I don't think anyone would pay money for such a system or service.
I also had a similar idea a few years ago. I would scatter the planet with a network of GPS time and frequency synced HF receivers. The location of any HF station could be found using the time stamped delays delivered via the internet. Technically, it's not a major challenge. Financially and politically, it's a mess. None of the hams were particularly interested in locating a DX station exactly. The stations that might be worth finding were usually buried under a "pileup" where dozens of transmitters were on the same frequency simultaneously. The FCC already has a functional interferometer based system. The commercial HF bands are mostly religious broadcast stations, which have other ways of locating interference sources. There was some interest among CB'ers, but they had no money. It became a solution in search of a problem to solve so I gave up.
-- Jeff Liebermann jeffl@cruzio.com 150 Felker St #D http://www.LearnByDestroying.com Santa Cruz CA 95060 http://802.11junk.com Skype: JeffLiebermann AE6KS 831-336-2558
You've probably already tried this, but make sure the horizontal width doesn't change with intensity. And that it's not also short vertically. You can chase your tail if the HV bleeder goes open and the HV increases.
the crystal radio). I plan to start my experimentation first on the AM and FM broadcast bands and then move to the amateur bands once I get my license, so I initially won't go much higher than about 100 MHz.
intermittent access to a 1 GHz scope at work. Would that be enough for circuit verification?
analyzer (presumably from ebay)? I had read somewhere that even with low frequency stuff my oscillators or mixers could be giving out spurious oscillations at several GHz that I should be aware of.
and I wonder if those would be adequate for this kind of experimenting.
have very little experience with radio and so I expect there could be plenty of things going wrong spectrum-wise.
I have read most of the replies suggesting reading material. Do yourself a favor and get:
In my opinion, you will not find a better book to start your quest.
There are many more I could recommend, but I think you should absorb that one first.
Cheers and enjoy, John
By the way, if you feel that the material in that book is too simple for you, then get:
John
It was as crude as the equipment they developed it with.
I saw a W.W. II vintage Spectrum Analyzer put together by Crosley out of a modified communications receiver, scope and several panels of custom electronics, including several block down converters. It was a .5 to 30 MHz S.A. that filled an entire six foot relay rack. It was crude, it drifted and took a lot of work to set up & use, but it was all they had when they developed the shipboard RADAR for the US Navy at their Glen dale Milford Road, Cincinnati Ohio defense plant. It, and the 60 foot RADAR dish were still in place in the mid '70s to repair the last of the early shipboard RADAR systems.
Yes I've done that, the intensity and focus stays put. It's a weird thing that happen. Instead of getting the full width of the screen I only get 75% of it.
Jamie
WWII radars had ranges within about 2:1 of theoretical limits. A good tube communications receiver or SSB transceiver was as good as anything you can buy today, except for frequency drift. Some specs may well have been better.
-- John Larkin Highland Technology Inc www.highlandtechnology.com jlarkin at highlandtechnology dot com Precision electronic instrumentation Picosecond-resolution Digital Delay and Pulse generators Custom timing and laser controllers Photonics and fiberoptic TTL data links VME analog, thermocouple, LVDT, synchro, tachometer Multichannel arbitrary waveform generators
to the OP, if you have a SA at work, then you know how valuable it can be in troubleshooting..
suggestion, since you have a scope..
design or look up how to build a workable 50 MHz to 1GHz SA from an old Cable TV converter box, that uses your scope as a display..
with the wide range log/ RSSi chips they have today, its rather easy...
Mark
Nice. Fast true RMS meters like the 8920A or HP's 3400A or 3403A are really useful for RF noise measurements. On Gaussian noise, peak-reading voltmeters read low by 1 dB and analogue spectrum analyzers read low by about 2.5 dB, which can be a trap for young players, as Dave Jones says.
I often use RC lowpass filters together with one of those true RMS meters to measure the noise of TIAs. The RC lowpass has a nice predictable response, so you don't have a lot of extra sources of error.
Cheers
Phil Hobbs
-- Dr Philip C D Hobbs Principal Consultant ElectroOptical Innovations LLC Optics, Electro-optics, Photonics, Analog Electronics 160 North State Road #203 Briarcliff Manor NY 10510 USA +1 845 480 2058 hobbs at electrooptical dot net http://electrooptical.net
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