Hi Dale,

Does this only apply to 1/2 wave long end feds only?

Does this apply to any frequency?

The maximum space here is only 66 feet at best.

What options am I left with that would work for 80-40 meters?

I have a question about traps. I read yesterday that traps should not be
tuned to resonance of the wanted frequency. If I constructed a homebrew trap
for say 7.1 MHz.
How far away from this frequency should I tune the trap?

Should it be tuned higher or lower?

I did search the internet, but I could not find any info on whether its best
to setup the trap higher or lower than the wanted frequency and by how much.

Andy




"Dale Parfitt" wrote in message
news:K3X2k.2824$lE3.246@trnddc05...

"Andy" wrote in message
...
I have just put up an 80 Meter End Fed Flexweave wire. Its about 63 feet
long and fed direct with 50 Ohm coax at the far end of the garden. The
shield is connected straight down to a ground earth stake at this point
and it is tuned for 3.700 MHz. It receives better than any thing I have
used so far, but it is very death on 40 meters. Almost unusable.

Is there a reason for this?

The antenna is only up at 20 feet and my old G5RV is only 6 feet off the
ground at the moment and receives far better on 40 meters than the End
Fed wire.

73 Andy
Yes there is- it's a half wave long on 40M which implies voltage feed and
a VSWR in the 60--80:1 range.

Dale W4OP

Andy wrote:
I have a question about traps. I read yesterday that traps should not be
tuned to resonance of the wanted frequency. If I constructed a homebrew trap
for say 7.1 MHz. How far away from this frequency should I tune the trap?

Should it be tuned higher or lower?

Tune it for lower than the operating frequency to
minimize trap losses. The point to shoot for is
the maximum inductive reactance point which is
at a lower frequency than the parallel resonant
resistance point. How much lower depends upon
the Q of the trap.
--
73, Cecil http://www.w5dxp.com

I have nothing here to measure the Q of the trap.

Is there another way of working out the correct frequency needed for the
trap?

The traps are made from RG58 C/U. I think these are a low Q but I'm not
sure.

Andy


"Cecil Moore" wrote in message
...
Andy wrote:
I have a question about traps. I read yesterday that traps should not be
tuned to resonance of the wanted frequency. If I constructed a homebrew
trap for say 7.1 MHz. How far away from this frequency should I tune the
trap?

Should it be tuned higher or lower?

Tune it for lower than the operating frequency to
minimize trap losses. The point to shoot for is
the maximum inductive reactance point which is
at a lower frequency than the parallel resonant
resistance point. How much lower depends upon
the Q of the trap.
--
73, Cecil http://www.w5dxp.com

Andy wrote:
I have nothing here to measure the Q of the trap.
Is there another way of working out the correct frequency needed for the
trap?

Sorry, I would just be guessing. I made my 40m traps
resonant on 7.4 MHz and they worked well over the
40m band. But I never made any measurements or A/B
comparisons.

The traps are made from RG58 C/U. I think these are a low Q but I'm not
sure.

The following web page might be of interest:

http://www.seed-solutions.com/gregor...n/CoaxTrap.htm
--
73, Cecil http://www.w5dxp.com

I've given up on this idea for now. I just can't get any ground wires above
or below ground here at present and the couple of earth rods that I have
sunk in just doesn't do the job.

73 Andy


"Cecil Moore" wrote in message
...
Andy wrote:
I have nothing here to measure the Q of the trap.
Is there another way of working out the correct frequency needed for the
trap?

Sorry, I would just be guessing. I made my 40m traps
resonant on 7.4 MHz and they worked well over the
40m band. But I never made any measurements or A/B
comparisons.

The traps are made from RG58 C/U. I think these are a low Q but I'm not
sure.

The following web page might be of interest:

http://www.seed-solutions.com/gregor...n/CoaxTrap.htm
--
73, Cecil http://www.w5dxp.com

Andy,
You have learned something though. Those 'ground/earth' rods
aren't all they are cracked up to be, not exactly the 'best' choice in
every case (especially for lower frequencies). Not much consolation,
huh? Oh well, that's the way it goes...
- 'Doc

Hi Doc,
Yep I guess I've learned that earth rods on there own are a no-go for
end-fed wires at those frequencies. I shell know better next time.

73 Andy


wrote in message
...
Andy,
You have learned something though. Those 'ground/earth' rods
aren't all they are cracked up to be, not exactly the 'best' choice in
every case (especially for lower frequencies). Not much consolation,
huh? Oh well, that's the way it goes...
- 'Doc