100 Miles with 10mW using an HT?!

[jwt873]

I read somewhere that Voyager 1 and 2 used 23 Watts. Either way, 10W vs 23W isn't much of a difference.

The satellites are equipped with 3 meter (9 foot) dishes which provide very high gain as kayn1n32008 points out. Not only that, they use 130+ foot dishes on the earth side to receive the signals.

Out of interest, Voyager 1 is out of the solar system in interstellar space and they're still communicating with it. At the speed of light, it takes 37 minutes for Voyager 1's radio signal to reach earth. V'Ger is 12.5 Billion miles (20 Billion Km) away. Where are the Voyagers - NASA Voyager

 

[prcguy]

Even more important than the Voyager transmit antenna is the receive antenna that NASA uses for various deep space projects. One of them is about 230ft in diameter and would have around 75dB gain at 10GHz used to receive Voyager data.
prcguy

Voyager may only transmit woth 10w but the antenna has in excess of 30dB of gain... ERP is a much more useful number in this instance.

 

[KC4RAF]

Mr. G, low power is quite the thing.

I like the idea of QRP transmitting because THAT is really cool. Using high power, like 500 to 1500 watts is okay for what has to be done, but it is quite the doings of using 5 watts or less and talking, CW, hundred miles or more.

 

[kayn1n32008]

I read somewhere that Voyager 1 and 2 used 23 Watts. Either way, 10W vs 23W isn't much of a difference.

The satellites are equipped with 3 meter (9 foot) dishes which provide very high gain as kayn1n32008 points out. Not only that, they use 130+ foot dishes on the earth side to receive the signals.

Out of interest, Voyager 1 is out of the solar system in interstellar space and they're still communicating with it. At the speed of light, it takes 37 minutes for Voyager 1's radio signal to reach earth. V'Ger is 12.5 Billion miles (20 Billion Km) away. Where are the Voyagers - NASA Voyager

May want to recalculate that time delay... voyager 1 is hours of propagation delay. Mars is between 15-20 minutes

Edit: Voyager 1, light time round trip, is 37h 12m so one way is more than 18h 30m.

 

[Project25_MASTR]

Just went through that with one of our local VHF repeaters. 71Km away, with 10mW out of the PA(before duplexer and 100+m of 7/8" hard line.) and I could still hear it, and it was still usable in the city, and I was still hearing it at my place... PA was replaced this weekend and it is now running at a whopping 17 watts.

I can see needing a PA running 100 watts if being forced to combine into a community antenna(with at least 6dB loss in combining) but to run a 100 watt PA just because it's 'cool' will make an unbalanced repeater in most cases. Here on the prairies, even a 50 watt repeater will be unbalanced. I just finished a business trip into BC, and in the national parks, the VHF Parks Canada repeaters were 4 watts.

I know of a UHF repeater that puts out 12.5 watts before the duplexer, through 100+m of feed line and is very well balanced for a 45w mobile.

I run more power usually (though still keep things fairly well balanced). It often depends on your geography. May be mostly flat where I am from but the noise floor is higher than you would expect (902 is a mess here) so I generally design accordingly. We generally run our local Ironman qualifier on a 8W GE Custom MVP. Provides complete coverage for the event. I generally try to build more compact variants but I have a few Custom MVP's laying about as well.

Another tool is using voter-comparitors to increase receive coverage with a single transmitter site (since simulcast on analog FM doesn't really work).

 

[kayn1n32008]

Simulcast FM works just fine on my local EDACS system. Single High power transmitter with lots of voted receivers is easier than teying to control the phase of multiple transmitters

 

[Token]

May want to recalculate that time delay... voyager 1 is hours of propagation delay. Mars is between 15-20 minutes

Voyager 1 is currently a bit over 20 billion km form Earth, the one way path time is just over 18 hours and 35 minutes, and increasing daily, naturally. The Mars delay is variable, as its distance from us changes through the year. Right now it is about 15 minutes and 55 seconds away. The Mars orbiter Odyssey is currently being tracked by DSS-26 at Goldstone and the received energy from the 8.41 GHz link is about -133.4 dBm.

(edit) Ooops, you edited your post while I was typing mine...DOH!

T!

 

[Token]

Even more important than the Voyager transmit antenna is the receive antenna that NASA uses for various deep space projects. One of them is about 230ft in diameter and would have around 75dB gain at 10GHz used to receive Voyager data.

You can say that number, 230 ft diameter dish, but it really does not hit home how big an antenna that is until you stand under them. Driving up to DSS-14 at Goldstone, DSS-43 at Canberra (and I assume DSS-63 at Madrid, although I have not been there) and seeing these things come up over the horizon, or pop up around the edge of the hill is astounding. As you approach you realize just how big they are, and once under them with your head leaning back you realize there is this thing a bit under the size of a football field (over 2/3 the size) over your head, and it is moving.

T!

 

[902]

He was doing what a lot of people call "mountaintopping." On a very high mountain, very low noise at the repeater site (or maybe that's on another mountain) and no obstructions, I wouldn't be surprised. I also don't think he was doing 10 mW, but maybe there was a slipped digit or something.

I went on a June VHF contest maybe 25 years ago and had my Motorola service monitor with me. We were on a mountain and needed to communicate with the Mt. Greylock club in Mass for a scheduled contact. The transverter smoked, but what I had could generate a signal just fine. I dialed into the frequency and keyed CW using the signal generator switch. Made the contact just fine. Output power was 0 dBm (1 mW) into a long yagi.

I've also hit repeaters in Philadelphia using a portable radio while looking across the river into New York City during tropospheric ducting episodes. I've also had people in Boston hit my repeater in NJ.

These are two different propagation modes, but it's certainly possible. I wouldn't count on that being an everyday occurrence, though.

 

[prcguy]

And there is no waveguide or feedline connecting the big Goldstone and similar dish feeds up high in the antenna to the equipment below. There is a series of RF reflective mirrors that track and bounce the received signal from the feed to the equipment that must stay aligned while the dish moves and tracks. Its basically an optical path between the feed and the equipment.
prcguy

You can say that number, 230 ft diameter dish, but it really does not hit home how big an antenna that is until you stand under them. Driving up to DSS-14 at Goldstone, DSS-43 at Canberra (and I assume DSS-63 at Madrid, although I have not been there) and seeing these things come up over the horizon, or pop up around the edge of the hill is astounding. As you approach you realize just how big they are, and once under them with your head leaning back you realize there is this thing a bit under the size of a football field (over 2/3 the size) over your head, and it is moving.

T!

 

[KD8DVR]

Watching all sorts of radio related videos I came across a clip where some guy hit a repeater 100 miles (160 Km) away with a handheld Yaesu FT-60 on 10 milliwatt settings with a REGULAR antenna, then had a live voice contact as well!

That is so cool! Unbe-friggin'-lievable!

Of course, he did it from some very high mountain top (2076m high), but still, it's pretty amazing! Or is it fake? Can those radios be set to such low power level at all? Sounds very interesting. 100 miles with 0.01 Watt? Wow! https://www.youtube.com/watch?v=cz5F1QWZ_a0

Yes, it is doable. Mountain-topping is commonly done to see who can get farther with as little power as possible. Also consider FM voice satellite communications with an HT.

Power isn't the true measure of performance.

 

[wyShack]

If I remember right there used to be an amateur award for a verified contact over a distance of greater than 1000 miles per watt of transmitter power-One of my first radios was a Ten Tec model 509 that put out about 2 watts. I worked Australia more than once. it don't take much if conditions are right-and if they are not more power is of only limited use.

 

[ab3a]

The North American QRP CW Club (NAQCC) has an award for communication over a distance of 1000 miles per watt or better using less than five watts overall.

I have a friend who, many years ago, stood on the beach in Tel Aviv with a 2M hand-held radio set to 300 mW in to a portable 5/8 wave antenna talk to another guy in Malta over 1100 miles away. standing on the beach. Simplex.

And if that's not good enough for you, for many years a record was held by a couple Australians working with small dish antennas on 10 GHz running 30 mW. They communicated across the Great Australian Bight for a distance of 1100 km. They used wideband FM.

 

[902]

The other day I put my HF radio on 10 meters and let it sit listening for WSJT. I had the program set to report whatever it heard to the Internet to a logging website. Then I went out for a while. When I got back home after a few hours, I saw stations in South Africa, Brazil, Argentina, and Japan, in addition to quite a few US stations. I'm pretty sure most of them were QRP. My next stop will be 6 meters. I'll probably just park the rig there and leave it going. You just never know what you're going to hear if you just listen or are in the right place at the right time.

 

[SCPD]

I read somewhere that Voyager 1 and 2 used 23 Watts. Either way, 10W vs 23W isn't much of a difference.

The satellites are equipped with 3 meter (9 foot) dishes which provide very high gain as kayn1n32008 points out. Not only that, they use 130+ foot dishes on the earth side to receive the signals.

Out of interest, Voyager 1 is out of the solar system in interstellar space and they're still communicating with it. At the speed of light, it takes 37 minutes for Voyager 1's radio signal to reach earth. V'Ger is 12.5 Billion miles (20 Billion Km) away. Where are the Voyagers - NASA Voyager

Don't know that's possible when it takes over 4 hours one way just to receive a signal from Pluto. You should check your facts more carefully then give out wrong information.

 

[KC4RAF]

Yeah, he should have posted 37 hours rather

then 37 minutes! lol

 

[jwt873]

I humbly apologize for all the harm I caused

 

[KC4RAF]

Don't worry 'bout that, I saw how it was

easy to read the time wrong. lol
But what got me, that thing is traveling over 355 miles per minute! Or over 21 thousand miles per hour! That thing is haulin' butt...lol