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  #41 (permalink)  
Old 05-10-2018, 10:39 AM
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Originally Posted by dlwtrunked View Post
Designating 146.52 for calling only makes sense if both sides could easily switch to another channel. With today's radios that is not the case and invites an accident or invites a ticket.
I think that's a lame excuse to compensate for the cheap, Chinese, hard-to-program radios that are proliferating in amateur radio these days. Note that this comment is not specifically directed at you, but more of a general lament from someone who is quickly becoming an old fart.

There are radios on the market that will allow you to enter a frequency on the fly by pressing buttons on the DTMF keypad. Or, you could plan ahead and program a handful of simplex frequencies into your radio so you easily switch to them.
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Old 05-10-2018, 11:40 AM
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Originally Posted by needairtime View Post
There is a SNR limit at the receiving end based on background noise
Do you know the antenna gain, antenna HAAT, system loss, receive sensitivity and local noise level of every receiving station? If not then you can't calculate anything except the distance to the radio horizon and free space path loss for a particular frequency.
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Old 05-10-2018, 11:55 AM
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I use it all the time, along with various repeaters in my area.
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Old 05-10-2018, 12:10 PM
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Quote:
Originally Posted by W9BU View Post
I think that's a lame excuse to compensate for the cheap, Chinese, hard-to-program radios that are proliferating in amateur radio these days. Note that this comment is not specifically directed at you, but more of a general lament from someone who is quickly becoming an old fart.
I wonder if there's a market for a cheap radio with a rotary encoder for frequency? Agreed, keypadding in a frequency seems no different than texting while driving

It's even worse for repurposed radios, my LMRS radios don't even have keypads for tuning, I can't (yet!) switch frequencies on the go.
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Originally Posted by nd5y View Post
Do you know the antenna gain, antenna HAAT, system loss, receive sensitivity and local noise level of every receiving station? If not then you can't calculate anything except the distance to the radio horizon and free space path loss for a particular frequency.
Even if you don't know all the parameters, there should be a rule of thumb for an average receiver, average monopole antenna, and typical background noise level.

Perhaps after all it's an unreasonable expectation for a number, albeit there is such a number for CB - likely because these radios and antennas are typically more uniform than a random amateur radio station.
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Old 05-10-2018, 12:18 PM
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I have driven all 48-lower states and have made more simplex contacts than I can recall, but rarely by just throwing my call out there while cruising down the interstate. That happened more often when I was parked at a truckstop or rest area. Most if not all contacts I made on the interstate were when I saw an amateur radio antenna on a vehicle or read a pertinent bumpersticker that informed me that a fellow ham was in that particular vehicle.

I was also contacted now and then on simplex when someone saw the numerous antennas on my rig, the handheld radios on my dash-mount, or my call sign decal on the window.

Subtle advertising can work well out there!

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Old 05-10-2018, 3:05 PM
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It gets pretty active here in the midwest around hamvention. I drive from St. Louis to Dayton and back every year. Thursdays and Sundays are pretty active. Its fun to hear or talk to folks, and seeing their call sign on their cars as you pass one another. 10 miles is about the best Ive been able to make out based on the mile marker they call out at the time. 5 miles I can hold a good conversation with them but tends to get spotty between 7-10 miles out. It all depends on the terrain etc...
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Old 05-11-2018, 1:21 AM
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I have a few vhf/uhf simplex frequencies programmed into my FT8900R. Radio is usually on scan anytime I am driving. Not a super great amount of simplex traffic around here but there is some and I have made several contacts. When my ham radio co-workers and I would all come/go to work at the same time we would always talk on simplex. If one of us was out of range then we would switch over to a local coverage less used uhf repeater.
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Old 05-22-2018, 2:13 AM
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We have a net on 146.520 every Wed. night at 9pm central time. It's called by Bruce KB5WNU he is located just north of Jackson, Louisiana which is about 25 miles north of Baton Rouge. So if conditions are good feel free to check in everyone is welcome.
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Old 05-24-2018, 8:49 AM
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Just found out my 146.52 TX crystal is busted, at least my scanner says so...
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Old 05-24-2018, 2:08 PM
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Between DMR TG#3118, #310 and 146.52 I had plenty of company all the way from NW Indiana (almost Chicago) all the way to Xenia, OH for the Dayton Hamvention as well as the return trip.
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Old 06-17-2018, 11:28 AM
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Hi Needs--
.
"52", while called a National Calling Frequency is no assurance it will be a National Answering and/or Talking Frequency. The technical nature and limitations on the ranges of VHF play the ultimate hand in this deal. If you live in the middle of some metropolitan area, you *May* hear more activity than out in the wheat fields of eastern Montana- but then you might be surprised- hams out on the Plains, for instance, may be far more 2 metre active. Its a roll of the dice.
2 is really a short range band- if you want to hear regular activity it will have to be HF.
.
Unfortunately the changing demographics of the country has changed ham radio- 2 metre's was not immune to it. Once upon a time, everyone was on 2-- but the advent of the Internet, 'Cel Phones, streamed videos, etc. etc. has extract'd its toll- however, I'm preaching to the choir.
.
Using an old crystal based scanner is really handicapping you. I know its heresy here to use the words, "Baofeng," or what ever the latest-named Chinese spin off is- but you really can program them yourself (contrary to popular opinions,) and they will serve you fine as a start up if $$ is an issue. Your scanner may have been great in its day, but its a dinosaur now, Cowboy- put her out to pasture.....
.
I see by your profile you live in Colorado too. Where I am (somewhere in the mountains of the Arkansas) we have considerable "52" activity , seemingly the year around (yes, even in the dead of winter there are those that like to summit the 14-teen'ers with their handhelds)
Its called SOTA-- Summits on the Air- and its quite popular here in the High Country.
.
This weekend I'm home in the mountains, and just this morning I talked to a team of my favorite Summit Climbers on 52. They was 70 miles off , using a hand held with a rubber duck antenna (but with the advantage of +14,000 foot elevation)- If you get a Chinese hand held or mobile, take it on that exhilarating (!) drive to the top of Pike's Peak, -- from up there you will be line-of-sight clear to Kansas...and I can promise you (!!,) one short "...this is KA-zero-XYZ on Pike's Peak...." will change your mind about the dearth of 2 meter activity...
.
.
Lauri
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  #52 (permalink)  
Old 06-17-2018, 2:29 PM
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I had one or two more thoughts about this topic (as we await a break in the weather- a raging electrical storm/an aborted hike) -
.
Re-reading your question, Needs, about anticipated ranges on 2 metre's-

Like it was answer'd by others- there are so many variable to pin that on one formulae- but Number One is your radio horizon.... and that is the radio horizon for both stations.
.
I use the following formulae to calculate an Approximate radio horizon..
.
Distance in miles equals the square root of the height of the antenna in feet times 1.41
.
There are variations on this theme, and others will use a number different than 1.41, but that is what I was taught in school; its what sticks the firmest in my mind, and most of all: its what works for me.
.
Remember, this is additive for both stations, so hypothetically, if we re-use the Pike' Peak 2metre station example I present'd earlier- let's say this station is now trying to talk to a portable with an antenna 9 feet high.......
The square root of 8000 feet (although Pike's Peak is over 14,000, it is only about 8000 above the terrain to the east) is ~90.... that times 1.41 gives a radio horizon of ~ 127 miles. The Portable's horizon using the same formulae is about 4-5 miles--- additive, this comes out for a total of over 130 miles --- which will put your signal well north of Metro Denver,- practically to Kansas in the east -or New Mexico to the south--- (this is only for illustrative purposes....your mileage my vary... )
.
Another, this is really an off the cuff estimation-- was told to me years ago by a Motorola engineer:
"We tell our two-way (VHF) clients they an expect this--- 100 watts at 100 feet (antenna height) .....100 miles" (100 mile diameter, centre'd about the base station out to the mobiles.) Add a lot of Grains of Salt to that formulae, but still a useful guide.
.
.
Oh !, and please get rid of the 12 inch piece of wire as an antenna!... You'll never succeed with that ...........
.
.

. Lauri
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Old 06-17-2018, 3:00 PM
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Well hello stranger! We've missed your wisdom and warped sense of humour Lauri. I hope all is well with you and yours.
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Old 06-17-2018, 3:16 PM
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Ahhh...Look Who,s Back & with a New Forum Name ....Greetings....Welcome Back
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Old 06-17-2018, 5:28 PM
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Hey Guys, Thanks !
......Its the return of the Prodigal; it was job related, and if or when I get privilege to post on that section, the tale I will tell.... !
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Old 06-17-2018, 6:36 PM
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Thanks, yeah I hear a lot about putting this thing (Regency HR2B) out to pasture. It's a crappy receiver too. However, my intent is actually milking it for all it's got

Unfortunately yes, the 146.52 crystal (which is actually divided by 18 due to the multipliers) appears to be dead. So what do I do...

Make my own

Actually no, I'm not going to cut a crystal, H*LL NO. My plan was to design and build a VFO for this unit. Yes, capacitors, inductors, phase comparator, frequency multiplier, PLL, microcontroller, whole nine yards. I calculated out that the simplest VFO I can build I unfortunately can go no better than 10KHz steps receive and 5KHz transmit due to receiver design and the components at hand. While this actually works out well for 146.52, my transmit goal is unfortunately a 5KHz-step radio club repeater in the area which I know has listeners as I've heard some ragchewing on the scanner.

So what do I do with the transceiver, I won't be able to hear, even if I transmit perfectly on frequency? But wait, I didn't break my scanner suddenly! So to prove my design, I plan transmit on frequency and listen on the scanner. Done!

From my calculations I need at least a 17-bit divider for my PLL to get 5KHz step, but I'm too lazy to build such, at least to prove this idea will work. A 16 bit divider as these are easy to get -- one bit loss will double the step to 10KHz. Believe me, the added complexity of one extra counter bit is painful. I didn't look into 15KHz step and force it to land on the repeater because my calculations indicate that it then won't land on 146.52. Dilemma. Took the easy way out and just use the scanner for receive, and at least I should be able to use this transceiver for APRS as this frequency is on a 10KHz step.

I haven't calculated out phase noise/lock time, and of course this will get fed to my frequency counter before it goes on the air. I'll need to see how close my crystals are to the target frequency too, I suspect I can't use 50ppm oscillators so I'll need to hunt for better ones if the frequency is far off what I need it to be.

It seems very feasible I think... and whatever comes out of my VFO design will be easily translatable to my next, future goal: a more fully home-designed HF transceiver without hurting our trade deficit.

(and yes that piece of wire is gone... a piece of coax and stiff piece of wire has taken its place, though for the 70cm radio... )
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Old 06-17-2018, 7:48 PM
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Quote:
Originally Posted by needairtime View Post
Actually no, I'm not going to cut a crystal, H*LL NO. My plan was to design and build a VFO for this unit. Yes, capacitors, inductors, phase comparator, frequency multiplier, PLL, microcontroller, whole nine yards.
Sounds like you want to reinvent the GLB Channelizer.
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Old 06-17-2018, 8:31 PM
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It may well be, though I was thinking about a microcontroller based direct entry keyboard interface that can save channel information in its eeprom as well. Hopefully a lot smaller overall too - no wafer switches, etc. Still not sure if I'll be able to get the microcontroller to be able to handle so many things at once, but don't see why not...yet...
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Old 06-17-2018, 9:11 PM
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OMG Needs, you are a Dynamo of energy !
.
Its too bad I just changed hats (jobs) - We could have hired you with all your Go ! .... lol....
.
Seriously- you do have a dilemma when it comes to that defective crystal. When International Crystals closed shop last year that pretty much sealed the fate of consumer grade crystals. There may be another business out there (Bomar?) but that is just conjecture on my part- I have not order'd any custom frequency xtl's in years- everything we did in design used synthiz'd modules... they contain a crystal and their oscillator- multiplier/dividers- the crystal themselves might have been Mexican or Chinese in origin for all I know. The Big thing is, if you find someone who can grind you a replacement, the price will send you reeling !
On the other hand- you can try grinding down an existing crystal or doping one onto frequency IF you have one close to your desired frequency. A trick- use tooth paste as an abrasive to rise the frequency, or the touch of a graphite pencil to lower it. Those HC6 or 18 holders, however will really make for a challenge- unsoldering the cans- etc.--
.
Oh my !-- while you're at it, you might do a little particle accelerator designing on the side--- just so you'll not get bored...
.
I have ground more than my share of crystals- be it with ultra fine abrasives, or etched with Hydrofluoric Acid. Then you'll need a oscillator setup that mimics the capacitive. resistance inputs of your radio's oscillator to check and warp it to frequency, and an accurate counter to measure that frequency... and you are probably looking at a 0.005% accuracy requirement....... Is my point getting across here?...(laffs)
.
Building an LC circuit to mimic the crystal is also a possibility. Old(er) hams used to build VFO replacements to plug into the crystal jacks of their tube rigs. These things were about as stable as a bowl of Jello. My father tried such a "hombrew'd" fluke for 6 meters- he still talks about how-- for try as he might-- any vibration would cause it to FM. He even said that with a friend, they actually used it as an FM Modulator- no mic necessary. He would shout at the "thing' and it would deviate in frequency sufficiently (it was being multiply up to the 6th harmonic) to become narrow band FM on his friends receiver. In the days of AM that wasn't so bad a liability- but SSB sunk homebrew'd VFO's.
A cute trick, but don't go there...
.
I refuse to discourage your enthusiasm... but My God, Man, have you set yourself a task !- when a $25 Chinese radio would save you so much effort-- and you could always return to fight your Windmills another day....smiles
.
Good luck , Needs- keep me post'd
.
.
Lauri
.
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Old 06-17-2018, 9:48 PM
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When I was flying (USAF) we had two VHF and two UHF command radios, one of which was always tuned to Guard 121.500 and 243.000. Driving around I am either scanning VHF and UHF simplex or I'm parked on it.

I did make a call out on 146.520 once when we were in the mountains and happened upon some teens standing outside their inverted Ford Ranger, looking dazed. No cell coverage at all up there, so I got some help from someone who monitors the simplex freq.
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