Finally Built a Dedicated 30m Transmit Antenna... now for the receive antenna?

Discussion in 'QRP Corner' started by N5EIT, Apr 11, 2020.

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  1. N5EIT

    N5EIT Platinum Subscriber Platinum Subscriber QRZ Page

    5251300D-099D-4488-984C-85114E545EAA.jpeg 33B937A8-BACF-4B38-8ACE-C3BD9512710C.jpeg 898A8173-8C96-4C26-9A0B-9BE491C1F646.jpeg 0F970CF9-2C8F-4166-A61D-B6C1A5D5800B.jpeg A214EE46-0A2C-4B35-AD2A-9C9D950E3668.jpeg 034F6094-E06A-4F63-950F-ADB1EE18BC3C.jpeg C58AD3F5-76E2-46B9-8174-3DE184DFB31E.jpeg 0BFD9A87-B559-47EF-B78C-0C5B863936E4.jpeg A96789D1-4C3C-4A0E-A48F-81C503C37837.jpeg I’ve been primarily working 30m for the last few years. I’m not sure why I like this band so much, but I think its because I can make contacts just about any time I get on the air, and there is no contesting and high power users to fight against. I’ve made many DX contacts while working gray line and find this is my primary time to get on the air. I use an Elecraft KX2 and various other QRP dedicated rigs. I’m mostly out in nature and found that I frequently use a vertical wire and 16 counterpoise/radial wires when I set up camp. This configuration has worked great as a field expedient setup and I was wishing I had a dedicated vertical at the secondary QTH for 30m. I’m staying here while remodeling in hopes to rent it out in the future. I figured if I could build a dedicated 30m vertical in my smallish backyard that I’ll probably start working digital on 30m and get serious about DXCC or WAC, WAS, etc while relaxing in the early morning and evenings. So, I did just that this weekend while on COVID-19 lockdown. I wanted the center frequency right around 10.125 MHz so I could cover my favorite CW frequency of 10.118 MHz and the digital area around 10.137 MHz... The antenna consists of 14AWG THHN and about 28 feet of RG-8X that I had laying in the workshop. I used a sotabeams 10m fiberglass mast and duct taped it to a steel pipe that I cemented into the ground several months ago for my Ciro Mazzoni Baby Loop. Ive recently moved my Baby Loop and FTDX-5000mp to my primary QTH so I needed something decent for QRP work while staying and remodeling at this house. I used a ground rod that was already in the ground at the base of the mast to connect 16 radials that started out at 23’ 3“ so I could tune the antenna to get the least reactance. My radiating/vertical element started at the same length. I busted out the soldering station and soldered the center conductor of the RG-8x to the vertical element and a pigtail from the ground rod to the braid on the RG-8x. I laid out my 16 radials and used lawn staples to hold them down. Everything is soldered and the only connector is at the rig being a PL-259 with BNC adapter for the KX2. I will solder the radials to the ground rod clamp after Easter when I pick up my torch and solder from the primary QTH. Once I had the antenna set up I went inside where I ran the RG-8x thru a window feed to my station. I used the MFJ-223 and took some readings. My resonant frequency was around 9.292 MHz so I went out and cut a few inches off of each radial then I trimmed the vertical element down about 6 inches. This landed me at 10.119 MHz with zero reactance and a 37 ohm impedance. The SWR is right at 1.35:1 throughout the entire band with just a bit of reactance starting at 10.118 MHz going down and zero reactance from there up through 10.150 MHz. This was a good feeling to see that I’d been successful on the first cut and didn’t have to go back and forth all day. So, in summary I have built the most efficient antenna that Ive ever used unless there are significant ground losses. But, I tested my newly built joy on WSPR at 250mw and was heard in England and in all directions over the USA. During Gray Line, I checked on Reverse Beacon Network and called CQ with 1 Watt and I was heard from 8 - 12 dB by stations in Illinois, Virginia, Arizona, Wisconsin, Vermont, and Utah. I was happy to have that report and it seems that I’m not having significant ground losses from using the ground rod. I was worried about that because I’ve been told by some that a ground rod connected to the radial system would introduce significant ground losses. It has actually made a good difference in S/N ratio, where I had a lot of noise before using the ground rod and less after, with signals remaining about the same. I run my KX2 with AGC off and RF gain at around -5 to -10 most of the time and I can copy many stations that I couldn’t copy with other antennas even though the vertical is a noisy antenna by nature. I’m hoping to build a dedicated receive antenna to mount on the eaves of the roof outside a half wavelength away so I can pull in some weaker stations and start utilizing the vertical for its intended purpose...as a dedicated 30m transmit antenna. For now its pulling double duty and doing OK, but once I have a decent receive antenna I think I’ll be in high cotton. I’ll try to attach pics if possible. They show the antenna in my backyard and the analysis after finishing up. I may try to get that tiny bit of reactance on the lower end out by making a few more adjustments but its working FB for now. I primarily work 10.118 MHz and up, especially if I plan to work digital soon. I’m wondering what I should do for the receive antenna. It needs to be small and dedicated to 30m! Any suggestions are welcome!
     
    Last edited: Apr 12, 2020
  2. N5EIT

    N5EIT Platinum Subscriber Platinum Subscriber QRZ Page

    I forgot to add that my typical noise level here, with this antenna is about S2 so I’ve been running the KX2 with RF gain at -5, AGC off, af limiter at 20, pre amp off-and copying many stations that I couldn’t copy before. I can ride the RF gain and hear better than when I had the Ciro Mazzoni loop up. Although it was more quiet but the S/N ratio suffered as well. For a vertical antenna in the middle of town this antenna is not too bad! If I can build a small receive loop that will get that S/N ratio better then that’ll be wondrous.
     
  3. N5EIT

    N5EIT Platinum Subscriber Platinum Subscriber QRZ Page

  4. WL7PM

    WL7PM Ham Member QRZ Page

    A LOOP should be the first consideration when looking for 'Low Noise'......
    Might as well shoot for resonant while you're at it.
    99 feet circumference should get you close.
     
  5. KL7AJ

    KL7AJ XML Subscriber QRZ Page

    30 meters is sort of in that no-man's land between low and high band. A large frame loop is pretty good for the band, and not too large....4 feet across or so should give you a great signal.
     
    N5EIT likes this.
  6. N5EIT

    N5EIT Platinum Subscriber Platinum Subscriber QRZ Page

    Yes, loop is what I was thinking. A 99 foot loop is a no go. I need something small (that will fit on a rotator on the roof). Wish I had the space for a resonant full wave loop, but I don’t! The smaller large frame loop sounds much more doable since I’m in need of something small.
    I was thinking about a 1/8 or 1/10 wave loop w preamp and rotator. I’ve got all the stuff to build one without a preamp and I could build a preamp later and just use the preamp in the radio for now.
     
  7. N8AFT

    N8AFT Ham Member QRZ Page

    The RX loop experts that I hv listened to advise to build a loop on the size of .05 wavlength at the lowest freq.
    Yes, most are pre-amplified. Most are mounted not so high...
    Glad for you to make such great headway! I'm fortunate to hv a vert that loads easily and efficiently on 4 bands. It's a Cushcraft MAV-160.
     
  8. N5EIT

    N5EIT Platinum Subscriber Platinum Subscriber QRZ Page

    N8AFT

    Thank you, I was happy to verify the information I’ve been told by your and KL7AJ comments. 4.6 feet will be my dimensions and I’m hoping to start building one today. I’m actually going to pick up a copy of his ebook today.
    I’m impressed with your rig collection. I’m a fan of solid state and tube gear. I still paper log and don’t do any qsl other than mail. Seems proper CW etiquette has all but been abandoned by many. Glad to make your acquaintance and maybe I’ll meet ya on air sometime. Have a great week and stay safe!
     
    Last edited: Apr 13, 2020
  9. K8JD

    K8JD Ham Member QRZ Page

    I see the source of your noise right in the pictures. Can you guess ? (hint; Power lines)
     
  10. N5EIT

    N5EIT Platinum Subscriber Platinum Subscriber QRZ Page

    UPDATE

    No doubt about that. Never was a question of noise source. Although, being surrounded by power lines and transformers that pulse, I am happy with the installation. It’s not as noisy as my primary QTH. My primary QTH also has a super small yard, so no room for a vertical. Even with the urban noise here, I have had ragchews on 30m CW with a Canadian station and a Central American station to name a couple. So, my antenna is doing a great job as a transmit antenna. I’ve done more touch ups and it has Zero reactance and a 48.7 to 50.1 ohm impedance from 10.103 to 10.127 MHz. My Yaesu FTDX 5000MP was brought over 2 days ago and I’ve been using the noise suppression techniques that it affords. Which are many ... and when done properly can make a huge difference. Basically, I’m hearing more signals and putting out a better signal than I ever have on 30M. I’m hearing weak signals from Europe and having QSO’s with them. I set my Ciro Mazzoni Baby Loop up with the rotator and use it for receive. The vertical is a much better performer on transmit because of resonance. I’ve tested them and the reports show this—- it’s significantly better on transmit. I’ll actually build a receive only loop soon, so I don’t have to worry about pulse tuning the Baby loop and I’ll be able to use the receive antenna jack on the 5000MP. The Ciro Mazzoni is my primary antenna at the main home, so it needs to go back soon.
     
    Last edited: Apr 21, 2020

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