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FAQ: |
Can the EndFedz be used on bands other than the design band?
In general, no. These antennas are monoband. Using them with a tuner for
other bands wil guarantee that the coaxial shield will become part of
the radiating structure and may harm the matchbox.
What is the radiation pattern of the EndFedz?
Characteristics are identical to a center fed dipole.
How can I extend the bandwidth of the EF-10/20/40 on 40M?
In designing the EF 10/20/40 we intended to make an antenna that would
be portable and easily deployable. As a result, we use a choke to
isolate the first 33' from the remainder of the antenna. The choke,
then, acts like an inductor shortening the 40M half wave from 66' to
40'. If space permits, a 66' wire may be attached to the matchbox;
yielding wider 40M BW, and slightly more 40M gain. On 20M the antenna
will appear as a full wavelength. A 1 wavelength antenna has a null at
the horizon, and thus may not be suitable for DX work if the antenna is
deployed as a vertical. Deployment as a sloper or horizontal overcomes
this problem.
What limits the power on the EF-10/20/40?
The matchbox.
Can I use the EF-10/20/40 matchbox on other bands?
Yes, remove the factory supplied radiator and substitute a radiator
whose length is 1/2 wavelength long on the desired band - from 60M up to
10M.
Can I use my monoband EndFedz matchbox on a different band by replacing
the wire?
No. Each matchbox (with the exception of the EF-10/20/40) is different
and band specific.
Do the EndFedz require a ground?
The simple answer is no. With over 4,000 antennas in the field, we know
of one instance where RF was "in the shack." This occurred with the
antenna directly over the operating position. Moving the antenna solved
the problem. If you do ground the antenna at the matchbox, you will
likely see no change in VSWR or resonant frequency. The only conditions
where we were able to measure significant RF on the outer coaxial shield
occurred when:
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The coaxial length was an odd multiple of va wavelength
AND
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The rig was grounded.
In this instance we measured current -7dB down from the peak antenna
current. Changing the coaxial feedline length OR removing the ground
significantly reduced the currents.
Do EndFedz require a tuner?
No tuner is required, nor should one be used. Take the short time
required to tune the antenna.
Can I add additional 1/2 wave wires to the EF-10/20/40 matchbox and work
multibands?
No. Unlike a center (current) fed dipole in which a fan arrangement of
wires allows for multiband operation, the wires on an endfed (voltage)
must appear in series- either through a trap/choke arrangement or
harmonically related frequencies (eg. 7/14/21/28 MHz).
Can I combine coaxial cables from different EndFedz for a single
downlead?
No. You will need a remote switchbox or separate feedlines.
What is the black grease-like substance on the 10-32 threads?
It is a commercial product intended to prevent oxidation between
dissimilar metals in the electrical industry. We are using No-Gard® but
the same product can be found under other trade names. One interesting
aspect of voltage fed antennas is that corrosion at the matchbox will
have essentially no effect on performance. So our use at the matchbox is
simply to prevent the stainless hardware from galling. The only low
impedance connection on our antennas is at the 20M choke. On 40M, the
end of the choke nearest the matchbox is a high current (low impedance
point). So, on that 10-32 stud, the No-Gard® serves
the dual purpose of preventing corrosion and lubrication.
What is the best grounding arrangement for the EF-SWL?
Unfortunately, there is no one answer. That is why we have provided
separate grounds on the matchbox. Lug 2 is the ground end of the antenna
side of the transformer while #1 is ground for the coaxial shield.
Depending on the source of noise, it may be advantageous to: 1. Leave
the factory shorting strap in place and attach either lug to a suitable
RF ground at the antenna. 2. Remove the strap and ground only lug 1 at
the antenna site. Then, the receiver may be grounded or left ungrounded-
whichever results in lower noise.
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