analog VHF radio - Page 1
Forum section: electronics / rf-microwave

author: coppercone2
author_rank: Super Contributor
timestamp: November 30, 2024, 08:34:28 am
content: I am curious about the classics of VHF radio receivers, transceivers or transmitters. I see alot of it is for planes.Do they have some classic benchtop VHF radio equipment, kind of like the Collins R390?

author: rfdave#gmail.com
author_rank: Contributor
timestamp: December 03, 2024, 12:24:02 am
content: You might like this site for some classic sigint radios.http://blackradios.terryo.org/

author: coppercone2
author_rank: Super Contributor
timestamp: December 03, 2024, 01:55:33 am
content: I was thinking maybe more like radios found in air traffic control but that is somethingI thought ATC would have the best builds because it is super important they work correctly

author: CaptDon
author_rank: Super Contributor
timestamp: December 03, 2024, 06:58:34 pm
content: There was a military / FAA VHF amplifier coveted by ham radio operators. It used an Eimac 8930 or Amperex A393 tetrode. They were useful in the 108 to 135MHz range and could be modified for the 144-148MHz ham band. Most of the older VHF military gear was awful lame in sensitivity and power output. Aviation gear is A.M., most everything else in that 135MHz and up is FM. There was some military TED / RED gear that I believe was 200MHz to 400MHz and was bought up by hams but it wasn't very good. I don't really know of any VHF gear that set a standard like the R390 did for the lowbands. There was at one time a lot of Transverters and Converters which took advantage of the great sensitivity of lower frequency receivers and the stability of low band transmitters.

author: coppercone2
author_rank: Super Contributor
timestamp: December 03, 2024, 09:41:14 pm
content: Ok, that is what I was thinking, because I saw the builds for some higher frequency tube and early transistor equipment and it kind of looked scary hard, with things like discrete coaxial construction (we only encounter it in stuff like the tektronix 70ps pulser)I thought like maybe there was a period of time where the solution for VHF was to blast the transmitter, making it highly inefficient compared to Mw - HF radio, rather then to try to make a sensitive receiver.Have VHF communication power levels gone down over the years?But I also think maybe it was not researched nearly as much, because there is less magic to it. Maybe with tropospheric scattering there is, but it was not the thing where you can talk to another country through a little box that took the energy of a few light bulbs. The bored to utility ratio is just not similar... because it seems that even if you are bored screwing around with HF it can end up being useful, I imagine with VHF it was lonely.

author: CaptDon
author_rank: Super Contributor
timestamp: December 04, 2024, 12:59:22 am
content: With all of the significant improvements in semiconductor technology receiver sensitivity is incredible these days. Look at these ham band VHF/UHF dual band walkie talkies showing something like .2uv for near full quieting. Even at Xband marine and avionic radar frequencies the receivers today are probably 10dB better than something made in the 1970's. I had a Nems Clarke R1070 receiver / spectrum analyzer that was incredible. 55 to 260MHz and they made an R.E.U. range extention unit that was 250 to 450MHz plus 400 to 900MHz using what looked like a pair of television tuners. I wish I still owned it!! They are near impossible to find. It was my benchmark VHF/UHF rig! As the R390 was military and released in quantity to civilians there are also sigint Signal Intelligence stuff in current military use that would blow your mind but will never be released to the civilian market. Here is some 'sigint' for marine radar, I can see the pulse rise time, duration, decay, repetition rate and scan rotation rate. From that alone I can nearly identify the make and model of the radar unit, what distance range it is set to and even the health of the magnetron based on spectral splatter. And I can do that from 30 to perhaps 100 miles away!! You have seen audio waterfall displays using sound cards but know the same thing exists in the R.F. world also!! Here's looking at you....hehehehe. Cheers mate!

author: coppercone2
author_rank: Super Contributor
timestamp: December 04, 2024, 01:42:46 am
content: Oh yeah the navies have been paranoid about going obsolete to small robots since there was musings about a invasion of iran like 20 years ago, they probobly really don't want any more disadvantages at this point lol.. right now its super sketchy to do anything near a coast lineI find VHF interesting because of how tuners are built inside, the cheap ones, you think NO WAY because everything is black chips but they used to have a bunch of springs insideI never even wanted to scrap it because I thought its a bunch of springs, after the excitement of opening the first RF can I found that looked like thisthats like finding a interesting looking food box and inside its like bread when you thought it would be filled with cookies. usually metal wrapping means something good. not in the case of 90's consumer electronics. I thought there would be like fucking gold in that box. Maybe some big capacitors.

author: ftg
author_rank: Frequent Contributor
timestamp: December 04, 2024, 09:34:21 am
content: Quote from: coppercone2 on December 03, 2024, 01:55:33 amThe ATC radios are often remote mounted and the tower has only control panels, if the frequencies can even be changed.And with airband going from 25kHz channels to 8.33kHz channels a lot of the older gear got scrapped.And unlike HF equipment and FM landmobile radios, most are completely useless for amateur radio, so only collectors want them.The ATC radios often are just rack mount boxes with power and fault leds on the panel.Boring to look at, hard to modify and use antique modulation.

author: coppercone2
author_rank: Super Contributor
timestamp: December 04, 2024, 09:18:14 pm
content: I thought they might have a mobile test cart or something that is a bit more fancy then the usual equipment. For like trouble shooting, verification, stuff like that.Or like more tactical stuff for... smaller places that are temporary or really cramped or space is a premium

author: ftg
author_rank: Frequent Contributor
timestamp: December 05, 2024, 08:50:23 am
content: Test equipment is a separate thing.And the more portable solution is a handheld airband radio.

author: coppercone2
author_rank: Super Contributor
timestamp: December 05, 2024, 09:09:15 am
content: I think that a 390 is a 'test equipment'.If you needed a receiver in a lab, back in the day, I think it would be a damn good one.I used a SA with a speaker in it, but the only thing someone told me is they missed the real radio they had in the previous job. They do seem to use nice radios inside of a RF lab.There is a area of equipment I think that crosses over between test equipment and end use tools. They like end up 'being around' for various reasons. I think that nice receivers are one of them.Its less oddball then electric heater loads (space heater) that are kept commonly in many labs in north america. Because no one wants to buy a chromaI don't think a big HF reciever would be that out of place 20-30 years ago, even if your 'snobbishness' setting is set to 7.5/10, especially if its not your mainstay task. Of course, if your screw drivers require a calibration and verification check and alligator clip test leads are specified to +-0.005 inches, along with a ISO procedure on how to crack your knuckles, then it will get kicked out of THAT lab. Sometimes they go ape shit about equipment that might be possibly adapted to do something too, like a cheap wall clock, they really hate creativity. Makes me want to install a BNC connector on a stapler, that will surely get investigated by quality assurance. How can we be sure no one will use it to perform a unauthorized test?? We can't allow that printer because someone might try to print a ruler. Tables must not have any right angles, because it might get used to judge squareness. Maybe pour some sand on the tables too, so it can't be used as a surface plateThe best part is when the work place ends up being mad cheap and common objects are more trust worthy in determining a square then the malformed china import beat up square they have.Also, they have paper clip bans. I am not making that up, because they are worried that someone might make a steel jumper out of one, and screw up a test. Always made me think of that story where they repaired a b29 mid air to get it home after it got shot by flak, by bridging some damaged control with a paper clip.

author: ftg
author_rank: Frequent Contributor
timestamp: December 05, 2024, 11:13:35 am
content: The keyword here is "back in the day". When they were current they might have been a relevant device to test against.As a generic radio to use as a radio it could have been fine. At least if something with a big "NOT CALIBRATED" sticker would be ok for management.I somehow doubt getting them calibrated is easy these days.And I might have misunderstood the inital premise of this thread.As for using receivers in the lab, at work all of us in RF R&D have at least one rtl-sdr stick for just quickly looking at things.And at home I have used an AOR AR8200 a lot to listen to clocks and oscillators.Hearing what the clock sounds like does reveal things that might be harder to see on an oscilloscope.If you look at some documentaries of the USA radio quiet zone, they have a mounted AR8200 in their interference hunting van.

author: coppercone2
author_rank: Super Contributor
timestamp: December 05, 2024, 02:41:51 pm
content: Quote from: ftg on December 05, 2024, 11:13:35 amYOU WOULD THINK SO.the reality is different, they adapted to common sense.

author: CaptDon
author_rank: Super Contributor
timestamp: December 05, 2024, 03:54:13 pm
content: We had an R390 with a longwire antenna in one of our equipment racks at the AM / FM commercial radio station I worked for. It was almost exclusively used to listen to international radio broadcasts. Swiss Radio International, Radio Norway, BBC etc. It was very important to our news department during '91 and Desert Storm. We often also tuned to the M.A.R.S. frequencies to hear some of the comments from our men overseas. We had a list of the time schedules of the foreign broadcasters since they did the same 'report' but in different languages during the day. We also had a rack mounted digital clock in the same rack displaying U.T.C. / G.M.T. time. We engineers worked hard. I aquired 13 years of pension credit in 11 calendar years of service!! Here is an oddball for you, The ownership put $10,000 into a fund to be divided among three engineers. They removed $100 for every minute of lost air time due to equipment failures. To clarify, If a main transmitter went down but the auxilliary was available and on air then no money was lost. We also had automatic switching redundant S.T.L. studio transmitter links and I.C.R. inter city relay links. Somehow we always managed to lose about half of the money due to dumb stuff like when the Onan emergency generator (50KW) Ford 260 cu. in. engine governor went ape shit high RPM's and burned up the 50KW alternator and then sent a connecting rod right through the engine block. Lost several hours of our AM transmitter that day until commercial power came back on at the transmitter site.

author: shabaz
author_rank: Frequent Contributor
timestamp: December 05, 2024, 06:58:42 pm
content: Quote from: ftg on December 05, 2024, 11:13:35 amSame here, well worth having an SDR device for all sorts of work. Attached screenshot shows the sort of thing possible with RTL-SDR, observing a LoRaWAN transmission. Works just as great with FM of course.Regarding analog benchtop equipment, it's well worth checking out what some of the ham radio manufacturer offerings are. I've seen at some workplaces, that such radios have been modified to perform particular tests. Some of the early digital radio testbeds and demonstrations used such off-the-shelf analog receivers, with a signal tapped out to a custom PCB.Hard to go wrong with an AOR. I have several, with one of them, an ancient AR3000A, usable from HF to some microwave frequencies. I wouldn't recommend that particular model, because it is so old, quite early construction techniques internally, and a lot of the sellers on ebay may be selling it damaged in some way (there's enough complexity and it's a consumer-ish product, so some failures are almost guaranteed), without sellers mentioning that. I use it for general experimentation at VHF etc. There are some awesome high-end AOR models, e.g. AR5000, with prices equally high.A handheld AOR is a very nice option too, although it may need to be modified to get at an intermediate frequency if that's of use occasionally.

author: jwet
author_rank: Frequent Contributor
timestamp: December 23, 2024, 10:18:12 pm
content: A couple that I didn't see mentioned.Icom R7000 Receiver- DC to daylight receiver up through L band. Used to be a common item in RF labs.Yaesu FT-736x- these are actually transceivers but have a really nice low noise VHF or UHF front end on receive. Early use of GaAs iircIcom, Yupiteru and others made nice wideband portable receivers. They're handheld and usually have some scanner type features. The ICOM R1 was a tiny DC to 1300 Mhz unit that was very small, used to travel with one for years.

author: PA0PBZ
author_rank: Super Contributor
timestamp: December 23, 2024, 10:53:35 pm
content: Quote from: jwet on December 23, 2024, 10:18:12 pmR7000 starts at 25MHz, hardly DC. I have a R9000, 100KHz to 2GHz, maybe you are thinking of that?

author: jwet
author_rank: Frequent Contributor
timestamp: December 23, 2024, 11:24:56 pm
content: True- the topic was VHF so 25 Mhz is DC to that!There are many better/newer models- I was trying to recall old reliable type rigs of old that I remember seeing in real RF labs.

author: mr ed
author_rank: Regular Contributor
timestamp: December 24, 2024, 03:27:49 am
content: Aviation is all about reliability and standardization. VHF coms are AM, old school and usually installed as pairs of identical radios. Some use a handheld with a fuselage antenna. ATC has dual everything and backup power. Expect 10 watts rf, that is plenty except for high flying jets which need 200 miles coverage above 25,000 feet.