If there is enough interest, we could pull together a session for members to
build their own 40m or 80m EFHW antenna, for the BVARC January 23rd Club
Activity morning at the Bayland Park Community Center. The design would be this
(credit to Rick Hiller for the reference):
19-End+Fed+Half+Wave.pdf (squarespace.com)
EFHW Antenna --- Building The Transformer - YouTube
The parts are locally sourced (JPM Supply and Home Depot), either triple or
dual core unun (240-43), and the entire assemblage would cost roughly $60-$70.
We'd use the 43 material for the cores, vs. 52 - to reduce the cost. The 43
cores are readily available from JPM Supply.Members would reserve ahead
(pre-pay via Paypal) once a parts list is fully generated.
The antenna parts would be brought to the session, box pre-drilled, and a
nanoVNA would be present for preliminary testing.
73MarkK5MGJ
On Tuesday, December 29, 2020, 03:21:34 AM CST, Mark Brantana via BVARC
<[email protected]> wrote:
RonI do have a NanoVNA, and I like the dipole thought. The EFHW design has a
match. Basically a toroid. I will likely experiment with both antennas.Thank
you. 73.Mark N5PRD
Sent from my iPhone
On Dec 29, 2020, at 1:50 AM, Ron Bosch via BVARC <[email protected]> wrote:
And so everyone knows why I am up so darned late, I am waiting for the 02:22
ISS pass to download a stinking picture since I only have 2 more realistic
shots at doing so :-)
On Tue, Dec 29, 2020 at 1:43 AM Ron Bosch <[email protected]> wrote:
Mark,A few points that I couldn't make on the net, because of time.1. I wasn't
saying don't do it, just don't expect a bunch of QSO's. You will be limited to
when the band is really open, and the noise floor is low at the receiving
antenna. That will reduce the number of potential contacts by at least an
order of magnitude. That being said, operating anything is better than
operating nothing.
2. IMHO, and end fed antenna is not a good choice unless you also build a
matching bridge. You can't expect to maintain an exact 50-ohm load from an
end-fed with just a toroid, you also need some shunt resistors, and variable
caps, and such, and you will need to tune it depending on conditions due to
reactance unless you built-in a big enough reactance in the circuit, and cut
the end-fed to exactly 1/2 wave where you want to operate, and the toroid with
that much permeability probably ain't cheap. A better approach to me would be
a 20M 1/2 wave dipole trimmed at operating height with an antenna analyzer.3.
Doing this in the city, with the amount of interference, and the antenna
compromises we have to make seems to add a whole other set of issues to making
contacts. If I were to do it, I might plan to take the rig out of the city to
operate it, and get the advantage of using trees and such to get my dipole at
33 feet up, with a low noise floor to increase my chances of contacts.
4. In any event, I suspect you are really going to need at least a Nano VNA to
make sure you don't smoke the finals, since I doubt seriously that a QRP kit
includes protection circuitry. That will add a minimum of $50 to your build,
although you would save a bunch on the antenna if you built a 1/2 wave dipole
instead. Heck, I have an extra 1:1 current balun I can part with for the rock
bottom price of $0.02, and since I am including my $0.02 in this email, net due
is $0.00 :-)
RonKE4DRF
On Mon, Dec 28, 2020 at 11:44 PM Mark Brantana via BVARC <[email protected]>
wrote:
I thought I had things all figured out. I originally wanted to get back on HF,
and found I could get some great used equipment for about $400, not including
antenna. Add a 10-80 m antenna from MyAntenna for around $165. I already have
coax installed. Grand total: $565
Normally, this cost would not be an issue, but like so many others I am short
on funds due to CV-19, so it is a bad time for this expenditure. I find I can
buy a 20-m QRP Labs CW mini with case for about $90, and build an EFHW antenna
for another $20 (including the matching toroid). Grand Total: $110
Everything has its advantages though. A ham since ’78, that’s 1987, I feel that
1. this would force me to improve my almost forgotten code without the
inevitable distraction of voice alternatives,
2. this would give me a chance to build a full small project and antenna.
Today, though, some felt that this setup would lead to disappointment on my
part. I am fully aware there will be some limitations to QRP, but the generally
negative comments form our net were as follows:
1. The band is poor at this time.
2. The 4-5 Watt QRP would not get in, and even a 100 Watt unit would not
suffice, but needs to be about 500 Watts. This would lead me to need back to
spending at least $565, and more for an amplifier. (So we are now saying that
even a typical 100 Watt radio is insufficient?) (I would also note that QRP
sells a 50 W amplifier for this radio as an add on.
Experience counts. So, I am looking for my fellow hams with QRP experience to
share their thoughts. I thought I had this all figured out, but if I am going
down a wrong road, I need to know. What has been your experience with 20-m QRP?
Mark
N5PRD
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________________________________________________
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[email protected]
http://mail.bvarc.org/mailman/listinfo/bvarc_bvarc.org
________________________________________________
Brazos Valley Amateur Radio Club
BVARC mailing list
[email protected]
http://mail.bvarc.org/mailman/listinfo/bvarc_bvarc.org
________________________________________________
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BVARC mailing list
[email protected]
http://mail.bvarc.org/mailman/listinfo/bvarc_bvarc.org
