Sidebar Sidebar
  • You can now help support WorldwideDX when you shop on Amazon at no additional cost to you! Simply follow this Shop on Amazon link first and a portion of any purchase is sent to WorldwideDX to help with site costs.

To Master Chief and antennas experts

Robalo

Robalo

Well-Known Member
Aug 21, 2006
601
251
73
California
well this antennas is about 25' from ground to the feed connector, the coaxial is 0.8 ohms (dc ) now is well tuned on 27.700 1:1 great but here is the problem, i like to tune it on 27.205 (ch 20 )but i have 3.5" on TO1,T15P,T18P,and T43P also 4" on ground plane elements, i have 1" gap from RO2P strap to RO8P bracket and also have 1/2" from RO3P spider to PO8P bracket. and also on the joint of the 2 hoop rings i have 6" to WO8 INS wire, for me this antenna is too short. i played with WO8 wire in/out but nothing changed. any help would be greatly appreciated. I'll follow out your instructions

well heres my antenna

v58kb3.jpg


v582lm7.jpg



Master Chief said:
Set every element for 6" of overlap and adjust the TOP section for resonance (ground plane elements are 4" per instructions). Maco suggests adjusting "T43P" (second section). I'd much rather have a solid 6" of overlap here. You will find that the top section will have close to 12" overlap. Since they use the weaker .047 material, this overlap will actually strengthen the top of the antenna.

Take your antenna down and double check all measurments. Especially check the location of the wire tap. It's VERY easy to have the tap on the wrong side of the loop! The wire should tap closer to bottom bracket (P08P).

Set the antenna up on a 10' mast in your yard. Have a friend hold it. Check for frequency with lowest SWR. If your radio goes out of band, keep checking until you find the frequency with the lowest SWR. If it below channel 1, then your antenna is too long. Tip the antenna over and adjust the TOP section in 4"! Yes, 4"!!! Check SWR again and see if the frequency is now closer to where you want it to be. Keep adjusting the TOP section of the antenna until your lowest SWR is on the frequency you want (for me, it's ALWAYS channel 20).

Then, using a 6' ladder, move the tap in one direction and then the next until you get a dip in the SWR. It may read as low as 1.5:1 now.

Here is the important step that 99% of the people out there mess up on (except for English Bob; he gets it). Check the FREQUENCY for lowest SWR again. It may be above or below your desired frequency. Adjust the top section in or out to bring the SWR down even further on your desired frequency. Then re-adjust the tap on the loop! You will see your SWR drop even more! It should only take a couple of adjustments to get a PERFECT 1:1 SWR on your Maco.

What we have done here is adjust your main antenna element for resonance on your desired frequency, and adjusted your feedpoint matching network to allow your 50-ohm cable to feed a 5/8 wave antenna. Don't be suprised if you can hear better and talk farther. 2:1 SWR may work, but it is far from efficient.

Once you're done adjusting your antenna, then re-install it on your tower. The SWR may change a bit when you put it up in the air, but it will only be slight. Adjusting an antenna 10' off the ground has worked for 30+ years and is much easier than trying to do it on top of a tower! Good luck!
Click to expand...
 

Robalo, the wire that FL Native mentions is probably not a big problem, but I doubt it will improve the safety grounding over the low resistant shield of the feed line either. The feed line shield will likely provide a much lower resistance than this wire and look much larger to lightning or spikes.

I guess you have already attempted to get the antenna lower in frequency by adding the length that you have noted, but how much longer can you make it? From the photos the antenna looks to be pretty well in the clear so it should not be affected much by surroundings. The specific measurement in the docs should work. There is a caution note there about surroundings controlling the exact overall tuned length however.

The instructions show this very broad range for tuning, but I believe this antenna was very likely designed specifically for the middle of 11 meters, right where you want it. Maco's specific instructions speak to construction procedure for 11 meters only. You have unsuccessfully added length trying to lower the resonant frequency that you see.

If what you are doing has added reactance to the impedance mix then your coax is going to be reactive and incorrectly give you a different SWR reading at just about every point on the line. Try adding a small to med length jumper to your feed line and see if your SWR changes at the radio. If it changes substantially, then you probably need to rebuild it following instructions and then try tuning again with measurements more to the specs.

BTW, your reading of resistance in the line using an OHM meter is not valid.
 
I pretty much covered it in the original post.

Double check your exposed lengths...

T43P, T18P, TI5P = 42" exposed.
Set TO1 for the desired frequency.

TO1 on the ground radials should have 68" exposed.

Check the locaion of the radial hub (spider)! It should be 1/2" down from the bottom of the bracket (PO8P).

Double check the location of the wire tap! It should be closer to the bottom bracket. Bend the wire to split the difference between the base section and the loop. In other words, make sure the wire is in free space and not up against the base section. I usually bend it into an "S" using my fore finger and thumb.

Double check all your connections!

Make sure the little screw that holds the vertical element to the insulator is NOT also touching the base tube!
(for all you big watt guys out there, this is a weak spot in the Maco design! That small screw is so close to the base tube that it will actually arc and melt the insulator. Yes, I know the antenna is DC grounded. Maybe you can better explain the burn marks and the melted insulators I've seen on V58 and V5000s!)
 
thank you FL NATIVE,MARCONI and Master Chief
but it dindnt work i put it down more than 10 times 26.995 swr 1:9 and 27.405 1:8 1.0:1 on 27.700 i live with t
T43P, T18P, TI5P = 45"
TO1 = 69"
 
Hey Pescadito:
How close is the "Palm Tree" to any of the Antenna Elements???
Your SWR Readings show that your Antenna is "SHORT" in Lenght,(Higher Frequency Shorter the Antenna,Lower Frequency Longer the Antenna).
BTW RG8X is not the same as LMR400,check it out Pescadito.
Also stay that your Primary Operation Frequency will be 27.700 Mhz. and you lower the SWR for 1.0.1 there,as you center frecuency,you may need to sacrifice a little to obtain better SWR in lower frequencies like channel 20 27.205.
Dunno the Bandwith of your particular antenna????

Good Luck
Tecnicoloco
 
Hi:
You can find them at most of the Ham Stores.
MFJ-259B or MFJ-269.
They range from $200.00 to $350.00,Google Ham City,I believe is the place where I seen them cheaper.

Tecnicoloco
73's
 
well today i sold this antenna maco 5/8 it was a fair price. Now i'm going for v-quad,y-quad or comet or maybe m4c wich one would you chose? :? I do local 20-50 miles, also could be victor 4000. hmm? right now I have a99 which I don't like. If you have any idea tell me.

Hey weatherman49 the mfj-259b, power supply ,carring case and batteries I bought it at ham outlet store for $340.00

73sss
 
Hey Pescadito:
Stop messing around and get a Interceptor 10K.
!!!!!!!!Run to the pawn shop!!!!!!!!
Start checking the reviews in the A-1 Antennas Section.
Everybody says that is built like a tank,top of the line materials,very strong antenna,very low swr,also forget about TVI,ask Master Chief or Justin about it.

My 2 pesos
Tecnicoloco
73's

P.D.I just kidding Robalo(Run to the pawn shop).
:twisted: :twisted: :twisted: :twisted: :twisted:
 

dxChat
Help Users
  • No one is chatting at the moment.


      Top Bottom
      Back