| Author |
Message |
    
Deadly Eyes
| | Posted on Monday, September 02, 2002 - 10:08 pm: | 
|
I just noticed something. Almost every question is about a radio, an amp or a modification.
Hmmm I checked out the other good stuff that Copper sells (meters, freq counter, coax, and other goodies). Heck someone out there has to have a question of which coax is best? Which SWR meter is more accurate? Something.. |
Dx431
| | Posted on Tuesday, September 03, 2002 - 11:00 am: |
|
Ok, Deadly Eyes, here's a meter question for ya....What meter is more accurate? I have a Dosey 4001P, I know, I hear that Dosey's are not the best meter in the world , but it works for me.I intened to get the Astatic PDC 600 Tri meter so I can monitor swr,mod,watts at the same time. I know Dosey has a tri meter also, between the 2, which one is the best meter? Astatic or Dosey?? |
Dx431
| | Posted on Tuesday, September 03, 2002 - 11:15 am: |
|
Ok, coax.....I run RG8X on everything, my beam, groundplane,scanner and in my pick up. I dont run power, as of yet.I do, however, plan on running a 150w mod in the truck and no more than 400 on the base.The way I figure it, this coax is fine for my application. Now, if I was to run 1kw I would want to run what? LMR400? Beldon 8813 or whatever it is? |
Karatebutcher
| | Posted on Tuesday, September 03, 2002 - 5:14 pm: |
|
Deadly Eyes, I just looked at the meters that DX 431 mentioned, I to am looking for a meter, and I am looking at the Dosy TC3001, I like the looks of the unit, and it has the basic items I need, I am now running a Palomar Model 500, it runs good, watt meter and swr, I would like another meter for my newer base unit, which of the three would you suggest, I like the looks of the dosy meter 400 1P that DX 431 has also . As far as coax I run RG8U for my base units and in the future will replace it with the same more than likely, but as yet my SWR's are great. thank you |
Karatebutcher
| | Posted on Tuesday, September 03, 2002 - 5:25 pm: |
|
OK YOU SAID something,[1] do you feel elevation is a good factor in using a radio,[2] if you live on a slow upward hill, how can you tell how high it is? {3}on a standard watt meter, reading AM press key say ahhhh, on ssb can you do the same for ahhh pep? {4} can a swr reading be effected by radio waves on the frequency ? also give us some information on yourself in a profile
thank you in advance |
Taz
| | Posted on Tuesday, September 03, 2002 - 6:05 pm: |
|
hmmm |
Deadly Eyes
| | Posted on Tuesday, September 03, 2002 - 10:36 pm: |
|
RE Dx
No two meters are exactly the same. No two meters even of the same manufacturer are exactly the same.
For example: common caps, resisteors and such are rated +/- a few percent from the stated values on the component.
So as far as accuracy is concerned what you have to do is to apply a known power measurement aka volts and amps as measured by a very very accurate signal measuring device. A benchmark standard if you will. Then apply said signal at said values to the meters. Adjust the wattage on the meter to the value as caluclated using volts times amps.
Then too tempature can effect the accuracy of the meter as well.
But for all practical purposes in "General Daily" use just about any meter is good enough as long as it is in the ball park. Remember as a rule of thumb you have to lose half your signal to reduce the meter reading by one S unit. No one will ever notice the loss or gain of one tenth of a watt.
Which is why the hams do not worry about an SWR of 2:1. If you are pumping max 1500 the loss of a hundred watts is insignificant. You still have 1400 more to do the job.
DE |
Jburner
| | Posted on Tuesday, September 03, 2002 - 10:38 pm: |
|
Ok, how can I mod my meter to show more wattage from my amp so as to help me believe that I'm no mud duck. |
Karatebutcher
| | Posted on Tuesday, September 03, 2002 - 10:43 pm: |
|
WELL SAID , THANK YOU FOR YOUR COMMENT |
DeadlyEyes
| | Posted on Tuesday, September 03, 2002 - 10:46 pm: |
|
RE DX coax
Per our good host they sell mini 8 rated at 1000 watts, or was it 800. The also sell full size RG8 that can handle more power than the mini 8 coax. Other types of coax are also sold by Copper. HOWEVER my suggestion for anyone is to never run coax at max ability. Nothing manufactured by man is perfect. When you get to half of the rated power handling it is time to step up to the next level. No use risking equipment due to skimping on something as inexpensive as coax.
Also the coax you use can effect your receive as well as your transmit. If a given coax of a particular length if used for transmission purposes will lose half the signal strength in the coax then any incomming signal will be reduce by half as well. The loss door swings both ways. So use the lowest loss coax as is practical for the circumstances, the wallet and the frequency being used/listened to.
Check Coppers coax tables for ratings of coax or consult the ARRL Handbook, transmission lines section for the appropriate chart.
DE |
DeadlyEyes
| | Posted on Tuesday, September 03, 2002 - 11:08 pm: |
|
RE K and Ker
K:
Full RG8 is rated betweem 1500 to 4000 depending on the tupe of insulation between the center and shield. Mini 8 is rated below 1500. I seem to remember reading somewhere that it is rated at 1000 or was it 800 max.
So I like your use of RG8 where the use is justified. I myself use mini 8 almost entirely but only because I transmit not much more than 100 watts. BUT I would never use it on my VHF radio where the run of coax is longer than say 20 feet or so. I use full size RG8 for VHF and even at that I wish that I could affore heliax or hardline for the VHF rig. Perhaps when I win the powerball lotto!
Re Ker
Rather than saying ahhhh try counting to say 10 in your normal voice at your normal distance from the mike. Using a normal voice will allow you to better adjust using your normal conditions.
Many times max power distorts the signal and pushing certain components only shortens their lifespan.
Max power output does not always equal a good signal. The best dang signal I have ever heard in my life came from a ham op that fine tuned his transmitter using an oscilliscope running only 50 watts. He had that rig fine tuned like a razor blade. The signal meter was not huge but that vocal quality just BOOMED.
DE |
Deadly Eyes
| | Posted on Tuesday, September 03, 2002 - 11:13 pm: |
|
To adjust a meter....
There are two basic ways to adjsut a meter to read a certain value.
If your meter as want appears to be an adjsutment screw on the face of the meter then all you have to do is adjust the deflection using this external tension adjsutment.
OR the other way which involves removal of the case. Some types have varable resistors in the circuts that can be changed to adjust the defelection of the power meter.
But in the practical world perfection is not required in most cases. So if your meter is off by just 5% or so I would not lose any sleep over it.
DE |
Deadly Eyes
| | Posted on Tuesday, September 03, 2002 - 11:18 pm: |
|
Re Ker....
Your post request for background info. There are several members in the string at this time.
Were you re myself, DE, or were you asking info on another person.
DE |
Karatebutcher
| | Posted on Wednesday, September 04, 2002 - 10:02 am: |
|
Deadly Eyes again thanking you for your information , that was very interesting, I enjoyed reading it and will use your tips.I to will some day get the expemsive coax.Yes a profile would be nice, what state are you in, unit 536 northern Calif |
DeadlyEyes
| | Posted on Wednesday, September 04, 2002 - 6:15 pm: |
|
Re Kar....
I am in the State of Louisiana/in the South Central part of the state. I am just over 50 yrs old and have been a ham op since the early 70s. Currently I hold and Extra Class License. My primary delight is to make home brew antennas using wire, parts of old CB antennas, PVC pipe, hose clamps etc. Anything I can use that I can slap together that resembles and antenna that works. The I tear it appart and build another wierd antenna.
One more antenna tip. The PDLII antenna is as we know a two element antenna BUT if you can get your hands on a broken PDLII with the boom, one plastic hub and enough spreaders you can make a very nice 3 element quad that will give you more gain. All you have to do is to manufacure a director loop and place it on one end of the spare boom using a plastic hub. The length of the wire should be about 5% smaller than the loading loop length. Using whatever old pipe or material around splice the two booms together (I used an old piece of telescopic pole that slightly larger than the booms themselves to splce the two together. Relocate the boom mounting bracket to near middle of the antenna and there you go.
You may have to readjust the gama matching but you should see a much better receive strength and get much better signal reports due to the extra gain of the added 3rd element. |
Deadly Eyes
| | Posted on Thursday, September 05, 2002 - 12:05 am: |
|
Re Kar ...
Oops I forgot to answer your questions...
Q1, antenna height:
Height can be an important factor. It depends on the kind of antenna. Example 1, a horizontal dipole SWR can be adjusted somewhat by the height of he antenna above ground. Example 2, the lazy loop antenna is designed to operate relatively close to the ground so as to transmit almost in a vertical mode (they are called cloud burners). Example 3, Sloping dipoles and Inverted Vs are not effected by height although you need enough height to keep the ends off the ground out of reach of passers by. And in the case of sloping dpoles the close proximity of the ground helps to direct the signals in a favored directon. Example 4, The angle of radiation/signal per the book and pros says one half wave length but sometimes this is not possible so if you cannot get up to the book optimum as high as is legally possible.
Is higher better than lower. Not necessarily. While a lower antenna reduces the distance of your receive it also reduces the QRM as well. A trade off so to speak. It all depends on how badly the QRMing is and how close you are to putting a hand grenade under your rig and pulling the pin. :-O
Q 2, Hill Height...
The legal height for a CB antenna is 60 feet from the ground to the top of the tallest element or 20 feet if the supporting structure is a house or a tree. For Ham antenna the legal height is 200 feet unless you are in a historical area or near an airport (then the rules screw you).
Hills and signals. What is he best place to put an antenna in a very hilly area. I looked this up because there are no hills in Louisina worth mentioning. If you are going to put your antenna on a hill the BEST place is on the side you want to hear and transmit to just below the peak. A just Good place is on the top of the mountain, but then you have to listen to all the signals 360, including those you do not want to talk to. The positively worse is on the opposite side of the hill below the peak for obvious reasons. The hill gets in the way primarily.
Q 3, SWR...
First some basics to get everyone up to speed. If you want to link three independant electrical circuts together (the radio, the coax and the antenna) at each junction the impedance/resistance of each section should be the same to have the most efficient transfer. In this case the radio output is 50 ohms and the coax is 50 ohms (no problem) but the coax being 50 ohms connecting to a 200 ohm feed point at the antenna is a big problem. There will be a resultant SWR due to the 50/200 ohm conflict. In antennas the coax being 50 if it meets more than or less than 50 an SWR will result. The easiest way to estimate SWR is to compare the coax charastic to the feed point of the antenna charistic. In the above exampe of 50 to 200 you can expect an estimated SWR of about 4:1. It may be a little higher or lower because sometimes coax is not exactly 50 and the antenna feed point is not exactly what the book says it shoud be.
Conclusion...
I hope I did not confuse you too much. I will close with a true personal observaton. I was helping a family relative (medical Reasons) and I brought my Yaesu FT 101E so I could check into my usual nets on 80 meters. Well I put up a quick 80 meter dipole at a height of just 10 feet off the ground. At 80 meters the quarter wave length alone is 60 feet. The anetnna could just as well have been laying on the ground. Surprise!! The trash background noise dropped off at least by half and while the received signals were down a bit I could hear almost all the regulars just like I could at home. And while my signals to them were admittedly down a bit they could still hear me well enough to carry on with the net. Not too bad for an emergency quick rig antenna.
I hope I did not confuse you too too much. I have found that while the book may say one thing, the real world has a tendency to warp the results a bit. The best advise on antennas I can give to anyone is to: collect a library on the topic of antennas, be creative, and be inventive.
Later
DE |
Karatebutcher
| | Posted on Friday, September 06, 2002 - 6:22 pm: |
|
Deadly Eyes , again you have out done yourself, I made copies of the information that you gave us, and in the future I can see you are a person to ask questions. I see you are from Louisiana, that is a good state, I have talked there a few times from Northern Calif, a gentleman named Sonny DX 518. DX 122, DX437, THANKS AGAIN. |
DXCC
| | Posted on Friday, September 06, 2002 - 9:11 pm: |
|
Is there a bad state? |
Karatebutcher
| | Posted on Friday, September 06, 2002 - 10:37 pm: |
|
DXCC No, I must say, I should have said it is a beautiful state, all states in this United States of America are proud, beautiful states, and wonderful places to live ones small and short life in. And we will always stay proud and free. |
|
