I will throw another design into the mix. This would probably less than $15 if all you want is 20 m QRP. The parts are available at JMP. (Unfortunately, I am hunkered down at this time and waiting for a shot in the arm.) https://www.kb6nu.com/wp-content/uploads/2012/08/Endfed20.pdf <https://www.kb6nu.com/wp-content/uploads/2012/08/Endfed20.pdf>
> On Dec 29, 2020, at 10:52 AM, mark janzer via BVARC <[email protected]> wrote: > > 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) > <https://static1.squarespace.com/static/5b1576d036099b603985500c/t/5c5236b57924e85a9a1ccd62/1548891830343/19-End+Fed+Half+Wave.pdf> > > EFHW Antenna --- Building The Transformer - YouTube > <https://www.youtube.com/watch?v=sty7RlXQoJI> > > > 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. > > 73 > Mark > K5MGJ > > > On Tuesday, December 29, 2020, 03:21:34 AM CST, Mark Brantana via BVARC > <[email protected]> wrote: > > > Ron > I 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] >> <mailto:[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 :-) >> >> Ron >> KE4DRF >> >> On Mon, Dec 28, 2020 at 11:44 PM Mark Brantana via BVARC <[email protected] >> <mailto:[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 >> ________________________________________________ >> Brazos Valley Amateur Radio Club >> >> BVARC mailing list >> [email protected] <mailto:[email protected]> >> http://mail.bvarc.org/mailman/listinfo/bvarc_bvarc.org >> <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 > > ________________________________________________ > Brazos Valley Amateur Radio Club > > BVARC mailing list > [email protected] <mailto:[email protected]> > http://mail.bvarc.org/mailman/listinfo/bvarc_bvarc.org > <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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