| Author |
Message |
    
Sinker
Intermediate Member
Username: Sinker
Post Number: 340
Registered: 8-2005
| | Posted on Sunday, January 08, 2006 - 5:30 pm: | 
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Going to be tuning the Maco V-5000 in hopefully this coming week or next weekend.
I plan on taking it off the tower and putting it on a 10' pole in a wooden stand so I can get to everything to make adjustments.
I plan on having the full length of Coax and ground wire attached.
Now I have heard that when an antenna is tuned it should work with any radio (not sure if this is true). Yet I know that before each radio I have showed a different SWR Reading.
I plan on hooking each radio up identically as far a jumper lengths etc. of course the radio's and amps will each be different.
So what is the best way to go about this?
Should I use the radio I plan on operating the most to tune the antenna with and hope the others end up wit the same or very close readings?
If I end up with a good SWR Reading across the band can I still end up with a large rejection percentage? If so how would I correct this or even test it for that matter?
Should I tune the antenna with the amps ON or OFF?
I know everything is grounded well, have all new coax & connectors, radios have been tuned and aligned (well two of the three anyway). Once the antenna is up on the tower in it's 10' stinger I can not get to it to make any adjustments so need to get this all right the first time. I am willing to spend a lot of time - as much as it takes to get this antenna tuned correctly and as close to perfect as possible.
I will not be using the arrestor this time but of course will have the polyphasers in line still.
Please help me get this one right.... |
Tech808
Moderator
Username: Tech808
Post Number: 8912
Registered: 8-2002
| | Posted on Sunday, January 08, 2006 - 5:40 pm: |
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Sinker,
It is very easy.
Just follow the assembly instructions and pictures that will come with your antenna.
After following the assembly instructions it only takes very minor adjustments.
Have a helper and mount it on a peice of mast pipe tied to a non-metal stepladder to get everything set and then Up it goes.
Lon
Tech808
CEF808
N9OSN |
Patzerozero
Senior Member
Username: Patzerozero
Post Number: 2216
Registered: 7-2004
| | Posted on Sunday, January 08, 2006 - 5:56 pm: |
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with antenna 6-8' off the ground, whatever coax it takes to reach a xmitter will be fine to set SWR's. (if you were to use analyzer such as mfj259b, 'coax' would only be a couple feet long). antenna impedance will not change once it's in the air. nor will radio impedances change, so SWR's should be pretty close no matter what radio is hooked up.
take time adding accessories inline (amp, meters, filters, etc), assuring SWR's stay relatively close to the 1.01:1 you get the maco set to  ...with amp off. if they do go up with amp ON, just take your time swapping different length JUMPERS til it gets to where you want it. |
Marconi
Advanced Member
Username: Marconi
Post Number: 506
Registered: 11-2001
| | Posted on Sunday, January 08, 2006 - 6:39 pm: |
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If two different radios do not produce the same SWR reading for a given load then the radios are not producing the same ohms output, which should be 50 ohms.
What do you think affects the ohms output of a radio that would cause that to happen?
Sinker why don't you tune the antenna using whatever procedure makes good sense to you, and then ask your questions if things don't work out like you want. Just make a plan and stick with it until it proves to be either right or wrong.
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Sinker
Intermediate Member
Username: Sinker
Post Number: 341
Registered: 8-2005
| | Posted on Sunday, January 08, 2006 - 7:18 pm: |
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I will tune it as I did the first time (before the lightening). But wasn't sure if I should have the amps in line or not.
My reason for asking the questions first is simple. From the advice and experience of those before me, it can help prevent me from doing it wrong to begin with and (more importantly to me) prevent me from having to climb that darn tower again and remove the stinger and antenna to get to the everything.
I have removed a number of items out of the line as well and am down to one switch box, one 3 face meter and one dummy load/wattmeter. Taken all the other fancy but un-needed items out of line.
--- mount it on a piece of mast pipe tied to a non-metal stepladder to get everything set and then Up it goes ---
It's getting tough to find all wooden ladders now days. All I have are fiberglass with aluminum rungs - but I have that problem worked out.
I ask these questions as just like the glass jar myth and such I have heard to tune the antenna with the AMPS ON - with the AMPS OFF - with the AMPS OUT OF LINE etc., etc.. I know a number of you would know the correct procedure for this.
As for reflected power - is that directly proportional to ones swr????
BTW - Thanks for the speedy replies before I got started |
Al_lafon
Intermediate Member
Username: Al_lafon
Post Number: 148
Registered: 3-2005
| | Posted on Sunday, January 08, 2006 - 7:37 pm: |
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Your ladders are find as long as they are under
the ground elm.of the antenna. I tuned one 25
ft from a 8ft metal fence and it was ok. But
don't try this under real wet trees it will
change a lot. |
Patzerozero
Senior Member
Username: Patzerozero
Post Number: 2218
Registered: 7-2004
| | Posted on Sunday, January 08, 2006 - 7:47 pm: |
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'As for reflected power - is that directly proportional to ones swr????'-yes & no. high SWR guarantees high reflected power. high reflect can rear its head with a low SWR. turning an amp on & seeing high reflected power after seeing low SWR can be sort of described as being like feedback, that's why you can usually reduce reflect with amp on by lengthening jumper.
you must tune the ANTENNA for low SWR. & ONLY THE ANTENNA!!! nothing else can be tuned to adjust SWR.
BUT, YOU MUST ALSO:
have complete faith that your coax, amp, radio, & all accessories are 50 ohm & that all connectors are installed properly. if your SWR's are STILL perfect with everything inline & before turning that amp on, you are there!!!
don't worry about SWR going up with amp 'ON' til you get everything perfect to that point. should that problem arise, it is tackled on the ground & inside the shack. no need to even think about that til you're up to it.(& it may NOT happen) |
Sinker
Intermediate Member
Username: Sinker
Post Number: 342
Registered: 8-2005
| | Posted on Sunday, January 08, 2006 - 8:48 pm: |
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OK, now I am getting the feel for this.
So it may not be a bad idea to use an antenna analyzer to tune the antenna then correct. I will keep that ace in the hole available to me should I run into problems doing this on my own. |
Marconi
Advanced Member
Username: Marconi
Post Number: 507
Registered: 11-2001
| | Posted on Sunday, January 08, 2006 - 9:04 pm: |
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Sinker you note the following, "Now I have heard that when an antenna is tuned it should work with any radio (not sure if this is true). Yet I know that before each radio I have showed a different SWR Reading." By this, I take it that all you did was hook up a different radio to the same exact system and then checked the SWR. Were you using an inline meter or the meters in the radios and did you recalibrate at each check?
If this happens, do you know why? |
Patzerozero
Senior Member
Username: Patzerozero
Post Number: 2221
Registered: 7-2004
| | Posted on Sunday, January 08, 2006 - 9:34 pm: |
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for $225 MOL, the 259b is really if you're doing LOTS of antenna installs. it tells you just about everything about the antenna AND the coax, except the name of the guy who turned on the coax machine the day the piece was made  .
your maco should go down to 1.2:1 across all 40 real easy with just an SWR meter. THIS is when you start to remember things that were passed on to you during 1st install...SWR lower on 1 then 40, antenna needs to be shortened(easy way to remember is think that antennas get SHORTER as you go UP in freq-1/2 wave antenna for CB/11m is 18', 10m ham is a foot shorter, 6meter/50mHz is almost 1/2 CB size, 2meter/144mHz is real small, 70cm/430mhz is TINY), BIG SWR adjustments get made by adjusting length of antenna & fine adjust by ring, etc.
once you start remembering things, you could really assemble the maco without instructions-just a tape measure & calculator, & a bit of trial & error.
i remember seeing somewhere 'marconi(not marconi on this forum) was an experimenter too, & he didn't have the internet...' or something like that |
Road_warrior
Senior Member
Username: Road_warrior
Post Number: 1141
Registered: 7-2004
| | Posted on Sunday, January 08, 2006 - 9:37 pm: |
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Mount antenna at least 8-10ft off ground
and away from any objects that might throw
off SWR readings. Wide open space if thats
possible. Tune only the antenna with Nothing
else in line. If using SWR meter, use same coax
you plan on using. |
Kid_vicious
Senior Member
Username: Kid_vicious
Post Number: 1000
Registered: 9-2004
| | Posted on Sunday, January 08, 2006 - 10:46 pm: |
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i think im just re-iterating what others have said, but you gotta keep the post count up so...
when tuning an antenna; you want to make sure that you are dealing with the fewest possible variables (gremlins!).
so, use a radio that you trust.
in your case, i would use your galaxy turbo since you just got it back from having an alignment.
the power doesnt really matter, but if it were me; i'd use a dead key between 10-25 watts.
just a good median.
and remember to have the mic gain all the way down.
so, the setup is: turbo-known good jumper-SWR meter-antenna coax-antenna.
no filters, or switchboxes, or ANYTHING else.
you can test the jumper with a dummy load. 1.1 SWR means its good.
now tune the antenna for length. leaving the tuning ring wire wherever the manual states to place it.
try and get the SWR to be the same in ch. 1 and 40.
SWR higher on 1=lengthen antenna vertical sections.
SWR higher on 40=shorten antenna vertical sections.
start with 1" then move in 1/2" increments.
try to get the SWR below 1.5 on 1 and 40 by doing this.
now fine tune with the ring; going for the unobtainable 1 to 1 SWR.
now you know that your ANTENNA is tuned, and any other SWR issues that you may encounter will have to do with ground or jumper length.
a helper is nice, (good luck!) just make sure you move far away from the antenna each time they check the reading.
good luck,
matt |
Cornbrown
Intermediate Member
Username: Cornbrown
Post Number: 101
Registered: 7-2005
| | Posted on Monday, January 09, 2006 - 2:08 pm: |
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Sinker..... Do your initial SWR tune with just your radio and SWR meter in line..... Once you have your SWR set then you can put your amp inline...
Cornbrown |
Sinker
Intermediate Member
Username: Sinker
Post Number: 343
Registered: 8-2005
| | Posted on Monday, January 09, 2006 - 4:53 pm: |
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The local ham shop has a guy who will come tune your antenna with an antenna analyzer for $40.00 but you have to have the antenna ready for him. Meaning, in my case off the tower so he can make necessary adjustments. He does it all from right at the antenna with just a short piece of coax hooked up.
Of course then I will be adding 55' of coax from feed point, down tower to the Polyphaser and then another 75' of coax into my office. Seems like a lot of coax to add without making a difference.
Then again, what do I know!!!
Marconi - No I have three radios hooked up via a switch box. I did reset and adjust before each SWR Reading. The change was no a lot 1.1:1 on one radio 1.2:1 on another and 1.3:1 on the last.
To answer your question NO, I do not know why. I am still new to all of this and trying to learn. I am way ahead compared to when I came here in August 2005 and didn't even know one needed to worry about SWR, in fact I had never heard of it before. Guess I am a very late bloomer in life.
One of the reasons I stayed with this site and left the others is folks belittled me for not knowing how to tune my mobile antenna on the other sites. Heck I can walk down to the buss stop and get treated that way, all I wanted was a little help and to understand. The folks here have been great even though I'm a slow learner. I'm not going to lie, I still do not understand a lot of what is being said when things get technical and feel lost.
I like being able to talk to others though and have met some great people as a result. This is the only thing I have with no ties to it. My other love is Fishing but I ended up making that my present source of income (why I am broke) other than that I am at home most times as I have a son who has special needs but the radio lets me get out so to speak.
Tim |
Marconi
Advanced Member
Username: Marconi
Post Number: 509
Registered: 11-2001
| | Posted on Monday, January 09, 2006 - 8:26 pm: |
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I know you have taken some grief, but I thought most was just in fun. About getting this guy to tune. You have mentioned that you have tuned this antenna before. I assume the tune will go about the same. What happened to your tune when you raised it before? Did it change? If not and you think the guy can do a better job, then go for it. You might ask him "What If" it changes.
Re: your three radios. Because you have each on a switch box, that makes each hooked via a little different system to the extend there is a different feed line (jumper) for each. Luckly the difference is not much so I would not worry about it. Answer to the question "Why". When this happens it may be traced to a tuning and alignment technique used by a technician. I have seen tech's tune into a live antenna or a reactive dummy load and not really know what the actual load was. Thus the radio's output was skewed somewhat by this degree of error.
You comment, "Of course then I will be adding 55' of coax from feed point, down tower to the Polyphaser and then another 75' of coax into my office. Seems like a lot of coax to add without making a difference." You realize this and yet and still you consider to tune using this line. I think you understand that if you get a tune that is purely resistive then the feed line will be of no conquencies. This is why the guy you talked to will tune using a very short piece of coax, go direct to feed point, or at least use a resonant 1/2 wavelength line.
Good luck,
Marconi
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Sinker
Intermediate Member
Username: Sinker
Post Number: 346
Registered: 8-2005
| | Posted on Monday, January 09, 2006 - 9:32 pm: |
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Marconi - Thanks - the grief I have gotten was not from this site but another where I got slammed and called all sorts of names for being so ignorant and stupid THEIR WORDS. The guys who have teased me here have done so in good taste and I knew it was just a ribbing. I'm cool with that, heck what fun would it be if you didn't have new guys like me to pick on a bit. The OTHER sites though they were just plan mean and dirty. I don't sweat them but have no time for them now waste my time debating them.
I know you have a lot of knowledge (read a number of your posts although again about half I didn't understand - above my head) so you stating that the tuning to be done at feed point makes be feel a lot better.
Oh Yeah - I will be doing it myself first. If I run into problems I will then call the guy up and ask for help.
Again, all these responses offering assistance, guidelines and explanations is what makes this place great and why I keep coming back.
Thanks,
Tim |
Marconi
Advanced Member
Username: Marconi
Post Number: 510
Registered: 11-2001
| | Posted on Tuesday, January 10, 2006 - 9:46 am: |
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I try in all cases to tune and antenna at installed height just in case the earth affects the tune of the antenna, which it can and often does. In this case if I tune with an SWR meter I use a handheld AM transmitter, SWR meter, and short lengths of coax to get to the feed point. If I need to remain some distance away from the feed point of the device during tuning then I will use a tuned 1/2 wavelength line for the frequency of choice.
The analyzer is affected by a random line just like an SWR meter is, so I always try to tune using it right at the feed point and at installed height.
I have never been successful at pre-determining if an antenna will appear to change tune when raising it higher, just by looking at it.
The first thing I do with a new antenna is try and insure that the length is resonant at or near the frequency of choice with no regard for the exact tune or SWR reading it yields. When the lenght is set, then I attempt to tune for match.
If the match is not as I wish then I may tweak the length a bit in order to try and get a better broad band balance with the tune.
Sinker, the V58 can be tricky as to the exact length that Maco recommends. Read your docs carefully in this regard. I believe the overall length they recommend for 27mHz is correct, and it has to be right or tuning can present problems. |
Sinker
Intermediate Member
Username: Sinker
Post Number: 347
Registered: 8-2005
| | Posted on Tuesday, January 10, 2006 - 2:46 pm: |
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Well I don't have an antenna analyzer.
I do have a coupler but not enough strength the hold the radio there heheehe.
Guess a short piece of coax is the way I will go.
You said "I will use a tuned 1/2 wavelength line for the frequency of choice.
What exactly does this mean?
I have tuned this antenna before. It got hit by lightening and fried the coax connector so have to install a new one. It should be very close as I had it pretty close before, this time I just want to dial it in to as near perfect across the band as possible. I know I could have gotten it better before but was in a hurry to get on the air. This time I will take my time every step of the way.
Thanks for the info, it will help. Hopefully I will still see the marker lines from when I put it together as I followed the instructions to the "T" |
Kid_vicious
Senior Member
Username: Kid_vicious
Post Number: 1012
Registered: 9-2004
| | Posted on Tuesday, January 10, 2006 - 11:51 pm: |
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im not sure but the maco v-5000 may use a different so-239 than you can buy at most places due to the power rating.
does anyone know if this is the case or not?
matt |
Marconi
Advanced Member
Username: Marconi
Post Number: 512
Registered: 11-2001
| | Posted on Wednesday, January 11, 2006 - 7:18 am: |
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Regarding my comment about a tuned 1/2 wavelength line. Generally most CB antennas are made resonant in the middle of the band, at about 27.205 mHz. The Maco V58 suggest an overall length to reach that resonance at an overall length of 240". The docs give indications as to where this measurement is to be made, but the graphics do not depict exactally where the bottom point is. The tip is mentioned and that is easy. This measurement is crytical to the success of the antenna, so just read carefully and make sure you have it right.
A tuned (electrical) 1/2 wavelength of coax is noted to produce at the beginning of the line (transmitter end) the SWR condition at the load end of the line (antenna feedpoint). It is said that if the resonant frenquency of the antenna and this line are both tuned at the same frequency then this line will produce a mirror image of the load conditions at both ends of the line. The formula for making such a tuned feed line is:
492/frequency x Velocity factor = length in feet
This factor implies that most other random lengths of coax can produce an SWR condition at the source that does not necessarily equal that of the load.
There is probably a good chance that when an antenna is first constructed, that the tune is not yet set correctly, so maybe it is a good idea to either tune at the feed point in order to eleminate the affects of a feed line, or use a very short piece of coax to connect in order to minimize the affect, or use a 1/2 wavelength tuned line to give us a mirror image of the condition at the feed point.
Once the antenna is properly tuned, then the length of feed line will make no difference, because the load and the line are equal at 50 ohms resistive.
It makes no difference here whether one uses an SWR meter or an analyzer. Some will say if you use a Bird meter instead of either meter noted above, that the readings will not be affected as such. Personally, I do not believe that to be true.
The first thing I do in tuning is to try and determine if the antenna is resonant where I want it. This is determined mostly by the overall length of the radiator. If one takes severl SWR readings, both above and below frequency, and plots them on a graph then one can better see if resonance shows an SWR dip in the area of frequencies that we wish to tune to. In this case I basically disregard the actual SWR numbers are. Tuning for match will come after proper resonance has been determined.
Good luck. |
Airplane1
Advanced Member
Username: Airplane1
Post Number: 663
Registered: 5-2004
| | Posted on Wednesday, January 11, 2006 - 7:27 am: |
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How much power are you planning to run? if it`s not too much then the regular 259 connector will be fine.
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Sinker
Intermediate Member
Username: Sinker
Post Number: 351
Registered: 8-2005
| | Posted on Wednesday, January 11, 2006 - 10:03 am: |
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I do not plan on running power often but have the potential to put out some power - Not compared to the big boys but over 1KW PEP.
Marconi, I have read about velocity factors, well saw them listed on coax I was buying, didn't know what it meant but now think it might be fun to try and make my own cable perfectly matched for what I am doing with the formula you gave. See, now this is getting interesting..... |
Road_warrior
Senior Member
Username: Road_warrior
Post Number: 1146
Registered: 7-2004
| | Posted on Wednesday, January 11, 2006 - 2:36 pm: |
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Marconi,
I have a question. How does a person set-up
a Analyzer/meter close to feedpoint if ones
body itself close to antenna changes SWR
readings? Is it not also true that different
lengths of coax will change SWR readings?
When we set up my antennas i tried hooking
things up to feedpoint and very short piece
of coax. My body close to antenna made it
impossible. We then used a 50 ft piece of
RG8 to set it. Then, when i installed my
75ft Belden 9913 coax SWR changed. So, we just
set it up with the Belden and it reads extremely
low with a SWR meter or Analyzer in-line.
1:0:1 on ch. 35, stays that way 6 ch up or down
of ch.35.
I had no idea about the tuned 1/2 wavelength
of coax to try it while setting things up.
Ok, so i can understand this better. How does
one prevent SWR changes when your body is close
to antenna while using Analyzer/meter at or
near feedpoint of antenna?
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Tech291
Moderator
Username: Tech291
Post Number: 340
Registered: 11-2004
| | Posted on Wednesday, January 11, 2006 - 6:25 pm: |
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KV,
Your right,that is not the typical so-239 flange mount like they use on the V-58.Contacting Maco directly may prove fruitful.Otherwise you may have to purchase the complete match assembly.I do know it was at one time(and may still be)it was marketed as an upgrade for the V-58.Incidently,if you look closely at the connector it is the same thing used on most so-239 to 3/8 mobile stud mounts.
TECH291
CEF#291
KC8ZPJ |
Marconi
Advanced Member
Username: Marconi
Post Number: 513
Registered: 11-2001
| | Posted on Wednesday, January 11, 2006 - 7:19 pm: |
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Well Road Warrior, I can't refute your observations while tuning, but I have never noticed much of a negative response such as you suggest. I'm sure one would want to use some caution in that regard. I always stayed at some resonable distance maybe a foot or two at least below the antenna.
Regarding a tuned 1/2 wave line. Do you have an analyzer? An SWR meter can be used, but they are typically not as sensitive as the analyzer. If you also have a good dummy load and a T-connector, then I will give you a routine to run that can be helpful in proving this mirror image principal.
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Road_warrior
Senior Member
Username: Road_warrior
Post Number: 1147
Registered: 7-2004
| | Posted on Wednesday, January 11, 2006 - 8:13 pm: |
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Marconi,
I used my friends MFJ Analyzer. My SWR meter
is not working correctly. I think
i will purchase a Analyzer instead of another
SWR meter.
|
Kid_vicious
Senior Member
Username: Kid_vicious
Post Number: 1015
Registered: 9-2004
| | Posted on Thursday, January 12, 2006 - 10:47 pm: |
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thanks for the answer dennis.
do you think its just a different dielectric material?
do you think maco manufatures them, or gets them from somewhere else?
tim, did yo see tech291's post?
you need to know this.
matt |
Tech291
Moderator
Username: Tech291
Post Number: 343
Registered: 11-2004
| | Posted on Friday, January 13, 2006 - 1:20 pm: |
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Matt,
The material looks to be either teflon or hdpe.I really doubt if Maco manufactures them inhouse,probley outsourced to another manufacturer.
TECH291
CEF#291
KC8ZPJ |
Sinker
Intermediate Member
Username: Sinker
Post Number: 354
Registered: 8-2005
| | Posted on Friday, January 13, 2006 - 5:05 pm: |
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Yeah I saw that and am hoping what I have will work. Luckily before I installed the first one I bought I saw this post and went back down to the shop and found two more that looked similar to what was originally on it. Have one of them on it now. Hopefully it is right and will continue to work as well as it does now.
Got it tuned to to 1.1:1 on 40 and 1.1(1.5):1 on 1 - just a tad higher than 1.1:1 so am pretty happy.
The antenna is back up and one radio completely dialed in with matching SWR's with amp on or off on both sides of it. Still have two more units to completely dial in as well. My fingers hurt form pulling off and putting on those connectors on the 213. Once I get it perfect then I solder.
Taken a lot of tips from folks and putting it all to use this go round.
I do have some TVI now though but also it showed up at about 1.5KW of power on a non tube amp which I was told might happen so not to worried but need to address it.
Might get on for the Sunday Net but probably not yet this weekend as I want every thing perfect when I come back. Antenna tuned as near perfect as I can get, radio's tuned and aligned so sideband will be no problem and a little help if I should need it to reach out and touch someone.
So system one down - great SWR's and very low reflected power. Need to work the TVI then on to system number 2 then 3, then hopefully the mic's will be out and then onto the mobile - hoping the 175 watt S-9's will be out - oh my wife is gonna kill me...... |
Airplane1
Advanced Member
Username: Airplane1
Post Number: 665
Registered: 5-2004
| | Posted on Friday, January 13, 2006 - 8:24 pm: |
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Keep up the great work Sinker, your system seems to be well on it`s way. I wish I could say the same but when spring comes I will be busy like you are now. I`m going to be putting up a 35ft tower with PDL-2 that I got from a friend and if I like it that will stay up. If I dont then I am going with M103 flat and my tried and true Maco 5/8 above it like Tech291 has his setup in pic section. |
Cornbrown
Intermediate Member
Username: Cornbrown
Post Number: 104
Registered: 7-2005
| | Posted on Saturday, January 14, 2006 - 1:09 am: |
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Sinker make sure you also salder the braid side of the coax to the PL259 connector... Some people don't salder the coax braid to connector and it cause RFI and TVI. You should get a good low pass filter also to help with the TVI also. Sinker I also think you should have replaced your burnt coax with LMR400 or LMR600 Ultra Flex coax. I used to use RG213 but I replaced it with LMR400 UF to help eliminate some RFI and TVI when running high watts.
Cornbrown |
Sinker
Intermediate Member
Username: Sinker
Post Number: 356
Registered: 8-2005
| | Posted on Saturday, January 14, 2006 - 7:50 am: |
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I do indeed solder the braided shield as well on the coax. I have LMR-400 running from radio to polyphaser which is about a 75' run then 213 from the polyphaser to the antenna which is about 55'.
I went with the 213 as I had planned on installing a beam and was told that the LMR-400 would be to stiff (it is stiff stuff). Cost became a factor and, well, no beam for now but later.
Did a little checking and and the only thing I get interference on (other than those stupid touch lamps they end up turning on and off as I key up) is the monitor speaker for the Home Security System. I re-arranged things and it is pretty close to the radios now. We turned on every TV, radio, baby monitors etc., etc. in the house and no problems. Still it is there so need to address it and hope nothing with the neighbors. I did notice a few of them have those Direct TV dishes and they point right over the top of my house - hmmmm this may not be good. |
Cornbrown
Intermediate Member
Username: Cornbrown
Post Number: 105
Registered: 7-2005
| | Posted on Saturday, January 14, 2006 - 8:14 am: |
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The LMR Ultra Flex is just as flexible as the 213. Now The regular LMR400 is stiff. |
Sinker
Intermediate Member
Username: Sinker
Post Number: 357
Registered: 8-2005
| | Posted on Saturday, January 14, 2006 - 8:15 am: |
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Oh yeah I made the jumpers out of 213 as well. Only soldered one end till I got the length to work well and still show good SWR readings then soldered up the the other end as well.
All out of LMR-400 coax now but have a lot of 213 left.
Cornbrown - BTW I am only feeding that box with 1.5 watts |
Cornbrown
Intermediate Member
Username: Cornbrown
Post Number: 106
Registered: 7-2005
| | Posted on Saturday, January 14, 2006 - 9:39 am: |
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Good deal... what is the dead key and swing with 1.5 watts in????? BTW I am glad it's working for you..... I was having second thoughts about letting it go. You got a good box. |
Marconi
Advanced Member
Username: Marconi
Post Number: 514
Registered: 11-2001
| | Posted on Saturday, January 14, 2006 - 9:41 am: |
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Sinker, good to here things went well on your tune and on raising it up you had no problems.
It has been a long time since I ran AM with a big amp, but maybe try setting your dead key up a bit from 1.5 watts. 1.5 watts in might look good on the radio's drive, but the amp may be making the TVI by not producing as smooth of drive out of the amp if the radio shows a big drive.
Continued good luck. |
Sinker
Intermediate Member
Username: Sinker
Post Number: 358
Registered: 8-2005
| | Posted on Saturday, January 14, 2006 - 10:14 am: |
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Yeah maybe some fine tuning like Marconi says.
Right now I am feeding it with 1.5 watts and getting between 250 & 350 dead key (the meter lines are so small and close together it's hard to tell exactly) but a swing up just over 1000.
Cornbrown you can't have it back heheehe  - I will give you visitation right though Thanks again I am very happy with it.
Marconi - one of my upcoming projects is going to be to make some coax with the formula you gave me here. I have to wait a little while but will use it when I put up the beam and am excited to see how it works out. Thanks for all your help and advice. |
Road_warrior
Senior Member
Username: Road_warrior
Post Number: 1153
Registered: 7-2004
| | Posted on Saturday, January 14, 2006 - 11:39 am: |
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Sounds like you have done a great job!
JIM/PA/CEF375 |
Kid_vicious
Senior Member
Username: Kid_vicious
Post Number: 1023
Registered: 9-2004
| | Posted on Saturday, January 14, 2006 - 9:42 pm: |
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nice job tim!
on the connector: i doubt you'll have any problems unless you try to go above 2.5K. (someday!)
on the interference: if its only with the big box on, i would say a low pass filter coming out of the box will help. make sure you get a good one.
marconi also has a good point though.
they call these amps "linear" amps because they are supposed to amplify the incoming signal in a "linear" fashion.
a good rule of thumb is a 4 to 1 swing to deadkey ratio.
ex. if your deadkey out of the amp is 40 watts, then your swing should be about 160 watts.
if it is more than that, then some of the signal is distortion which can and will cause TVI.
so try adjusting the power out of the radio until the amp shows the correct linear characteristics.
you may have to adjust up or down, but with 1.5 watts; im guessing up.
later,
matt |
Kid_vicious
Senior Member
Username: Kid_vicious
Post Number: 1024
Registered: 9-2004
| | Posted on Saturday, January 14, 2006 - 9:45 pm: |
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tim, i forgot to mention; you might also try wrapping the wires from the offending speaker around a ferrite bead.
matt |
Sinker
Intermediate Member
Username: Sinker
Post Number: 360
Registered: 8-2005
| | Posted on Sunday, January 15, 2006 - 8:50 am: |
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Oops - A small set back. While re-arranging things had to unhook the jumper from the switch box. That thing was so tight and the box is mounted the desk - anyway messed up the jumper so have to make a new one. This one will be with 213 - it took forever finding the right length last time and now with different coax I am in for it again. Wish I knew the Velocity factor then Marconi's formula would save me a ton of time I bet. Looks like maybe NEXT Sunday.
Oh yeah almost forgot - the offending speaker is mounted inside the monitor (kinda like a TV). I can mute the speaker and then all is OK and the machine is not usually taping when I am on the Sunday Nets anyway. Thanks for the info though. |
Marconi
Advanced Member
Username: Marconi
Post Number: 515
Registered: 11-2001
| | Posted on Sunday, January 15, 2006 - 9:29 am: |
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Sinker just fix the fitting and don't worry too much about the jumper unless it acts up. That formula thing is not the cure for that problem. Just fix your jumper and have fun.
I quote an old saying from time to time:
Everything is always okay in the end,
if it's not, then it's just not the end yet. |
Dale
Intermediate Member
Username: Dale
Post Number: 259
Registered: 12-2002
| | Posted on Sunday, January 15, 2006 - 6:23 pm: |
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dumb question how ya find the velocity factor of coax.like i got 50ft of lmr 400 on my imax2k how would i find the velocity factor |
Tech291
Moderator
Username: Tech291
Post Number: 345
Registered: 11-2004
| | Posted on Sunday, January 15, 2006 - 7:33 pm: |
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multiply your coax lengh by .85(the Vf for lmr-400)
TECH291
CEF#291
KC8ZPJ |
Road_warrior
Senior Member
Username: Road_warrior
Post Number: 1157
Registered: 7-2004
| | Posted on Sunday, January 15, 2006 - 8:42 pm: |
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Velocity factor of LMR 400 is .85
Do a google search for Velocity factor
of LMR 400 |
Marconi
Advanced Member
Username: Marconi
Post Number: 518
Registered: 11-2001
| | Posted on Sunday, January 15, 2006 - 9:08 pm: |
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Dale it is a posted value by the manufacture. In ARRL manual LMR400 is 85% VF. |
Roninboricua
Junior Member
Username: Roninboricua
Post Number: 17
Registered: 1-2006
| | Posted on Thursday, February 02, 2006 - 2:48 pm: |
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What does the maco v-5000 have that makes it handle 5000 watts instead of 1200 like the v58??
Can the v58 be upgraded to handle more? |
