Antenna Problems - I Think

enewbold

COB Senior Member
Joined
Jun 19, 2005
Messages
823
Location
Columbus, OH
Aircraft
Varieze N42XP / GyroBee
Total Flight Time
1100
When I arrived at Mentone this year I quickly discovered my Xcom radio wasn't transmitting, however it was receiving OK. The problem turned out to be the steel whip antenna was broken off, leaving only the mounting hardware attached to the airframe.

No problem, right?

I ordered a new whip from Aircraft Spruce, got it in the next day, installed it and ... dang! Still no transmissions coming out of the radio.

The TX indicator comes on when I press the mike button, but still nothing coming out of the antenna. Do you suppose that attempting to transmit with the broken off whip managed to damage the radio internally?

Right now I'm using my portable intercom coupled with my Icom handheld radio so I can continue operations, but I'd like to ask if anyone has any suggestions on getting the XCOM fixed. Like recommendations for a repair facility that can do a quick turn-around for me, or other ideas on getting the radio to transmit properly?

Thanks very much, guys.
Ed Newbold
Columbus, OH
 
Ed, You can damage the "finals" in the radio. Transmitting without an antenna will cause this, or weaken the power output. Put a watt meter on it to check and see whats going on with it. Make sure your cable does not have a short in it. then check the standing wave ratio. SWR. Get it as close to 1:1 as possible.
 
Ed, You can damage the "finals" in the radio. Transmitting without an antenna will cause this, or weaken the power output. Put a watt meter on it to check and see whats going on with it. Make sure your cable does not have a short in it. then check the standing wave ratio. SWR. Get it as close to 1:1 as possible.
I've just ordered an SWR meter this morning, Brent. Should be here in a couple of days. How do you use a "watt meter" in conjunction with a transceiver?


Thanks, Ed
 
I am agains the whip antenna. I use a coiled antenna as shown. If you dont have a load the output transistor blows really fast. Also the SWR is also critical.
 

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ED, make sure your SWR meter will cover the 108-136mhz band. A "CB" meter will not work. It will have an "In" & a "out". The "in", is your radio and the "out" is the antenna. It should show your watts "out" on the meter when you key the mic. Also turn on the back feature and it will show your SWR. your antenna length will have to be shortened or lengthend to make the SWR as low as possible. The lower the SWR the further the radio will transmit and the more sensitive the recieve part will be.
 
Ed,

Why not get an AAE diplole antenna?! It's mounted inside and out of the way. No ground plane needed.

Mine has performed flawlessly with my Icom 22.


Cheers :)
 
Why not get an AAE diplole antenna?! It's mounted inside and out of the way. No ground plane needed. Mine has performed flawlessly with my Icom 22.
I think this is probably the best way to go, Harry. Do you have the 5I or 5T and where did you mount it?

Thanks very much,
Ed
 
When I arrived at Mentone this year I quickly discovered my Xcom radio wasn't transmitting, however it was receiving OK. The problem turned out to be the steel whip antenna was broken off, leaving only the mounting hardware attached to the airframe.

No problem, right?

I ordered a new whip from Aircraft Spruce, got it in the next day, installed it and ... dang! Still no transmissions coming out of the radio.

The TX indicator comes on when I press the mike button, but still nothing coming out of the antenna. Do you suppose that attempting to transmit with the broken off whip managed to damage the radio internally?

Right now I'm using my portable intercom coupled with my Icom handheld radio so I can continue operations, but I'd like to ask if anyone has any suggestions on getting the XCOM fixed. Like recommendations for a repair facility that can do a quick turn-around for me, or other ideas on getting the radio to transmit properly?

Thanks very much, guys.
Ed Newbold
Columbus, OH

Ed,

As Brent said the VSWR meter needs to work at least to 136 mhz.

As to how to connect a "watt meter". Most "watt meter" such as a Bird 43 with a 25C element requires a 25-T RF Coaxial Termination cost more than most people want to spend. Even on the used market you are looking at around $300 - $400.

While I like what Harry says about using a dipole antenna. I would caution even it's use around metal. It can be detuned when metal is close to the antenna.

As to your radio problem. I suspect the output transistors have been damaged. A quick and dirty test is once you have a VSWR meter connect the cables, per the instructions, key the transmitter (for a short period) and see if there is an output in the forward meter reading. If there is an output reading most likely the output transistors were not damaged. If there is no output more than likely the transistor are blown.

XCOM should be able to advise you where a repair station can be located.

Leon

(kc0iv)
 
As to your radio problem. I suspect the output transistors have been damaged. A quick and dirty test is once you have a VSWR meter connect the cables, per the instructions, key the transmitter (for a short period) and see if there is an output in the forward meter reading. If there is an output reading most likely the output transistors were not damaged. If there is no output more than likely the transistor are blown. Leon (kc0iv)
Thanks for the advice, Leon. As soon as the meter gets here I'll run the check on it. =Ed=
 
What is the best antenna to use on a bensen style gyro?
Where would be the best place to place it?
Does the metal rotor blades interfere with the transmitting or receiving of the antenna?

Thank You
Scott
 
I think this is probably the best way to go, Harry. Do you have the 5I or 5T and where did you mount it?

Thanks very much,
Ed



Ed,

I forgot to mention in our PM....It will be in the info sheet you should get with the ant. but this dipole will perform its best when mounted vertically to its worse in the horizontal. It's a good 45* when mounted to the the door post of the RAF.

And as Leon mentioned, a lot of metal could affect this dipole ant. but the only metal in close proximity to our installation is the edge of MY metal inst. panel and that's at a 90* intersect which does not affect my ant. performance.

If you have the lexan panel you have no interference issue at all.

This AAE dipole ant. has had nothing but good customer comments.


Cheers :)
 
OK I'm interested. I did a Google search but could not come up with supplier for the AAE dipole ant.

Where can I find one on the web?
 
Chuck,

Aircraft Spruce has the AAE ant. and it's $16 less than what AAE is asking.

I guess A/S has a web site??

You can't go wrong with the AAE Ant.


Cheers :)
 
Harry, Ignore my previous post. I found it. Thanks.
 
I have a bird meter, but not alot of elements for it.

It isn't hard to have more money in elements for the Bird 43 than the meter cost. Add the cost of a few coax adapters and you have even more $$$.

If I was buying today I think I would get an antenna analyzer. Something like a MFJ-269.

Leon

(kc0iv)
 
What is the best antenna to use on a bensen style gyro?
Where would be the best place to place it?
Does the metal rotor blades interfere with the transmitting or receiving of the antenna?

Thank You
Scott

There have been several good discussions on the forum about antennas.

Try searching for antenna.

One that comes to mind was http://www.rotaryforum.com/forum/showthread.php?t=12024&highlight=antenna Joe showed one at post #4.

As to having a problem with metal blades. It may or may not be a problem. You can get some flutter with weak signals.

Leon

(kc0iv)
 
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