- 4SQRP Kits recently built
Re: 4SQRP Kits recently built
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I have several efhw - 66ft, 126ft...all have a 49:1 with 15ft counterpoise wires. Also your coax shield will act as a counterpoise. I use a common mode balun (can be an ugly balun) at the 49:1 box. A 66ft efhw should have nil swr on 40m and 20m and be tunable on 10-40m. You can also ck out a homebrew 49:1 balun by placing a 2.5k resistor across the out put and measure swr at input with antenna analyzer. You should see R of about 50 ohms.
On Mon, May 16, 2022, 11:18 PM Larry Ryan <llryan@...
Being a late comer to 4SQRP (started with the Bayou Jumper) I have found the various kits really well designed and a bargin when compared to other gear on the market. My past QRP was my pair of FT-817s I carried all over the world before I retired from Hewlett-Packard. They were sold a few years ago with a goodbye to QRP. The BJ was too tempting so I'm back. BTW, I added the Souperuper and EZKeyer IIi/SMT to the BJ. I even bought an IC-705 to replace my FT817s.
I recently built 3 kits that I want to mention: 4S Tuner, QRPoMeter and the Transformer Experimentation Board
4S Tuner: I finished this tuner last night and tested it this afternoon. It went together quite well although it took a search for more photos of the coil winding and understanding the options. Basically, everything needed to build and use the tuner was in the manual. Using PCB material for the case is a fantastic idea. I like the design of the 4S Tuner because of the IN/OUT switch where you can set the tuner without melting your final transistor. The bridge design with a dummy load makes a lot of sense and I see it used with the QRPoMeter. For the test, I used an existing 66 ft long wire for EFHW pulled out to 73 ft. I also used the existing 30 ft counterpoise lying on the ground. No problems - it tuned right up on 20M with the inductor set at E or F (goes from A to L in steps). On 40, it tuned right up on L for the inductor (max inductance). I called a station in Bend, OR (I'm near Seattle) and got a 44 report. Then I switched from IN to OUT (duh!) and he copied me Q5! OUT connects the rig to the antenna rather than to a dummy load and bridge SWR detector. This tuner is a worth while project and will go with my Bayou Jumper to simulate the actual Paraset use of a longwire antenna.
QRPoMeter: I didn't get this through 4SQRP but directly from NM0S. I learned about it from this group, however. This kit went together quite well with excellent build instructions. Like the 4S Tuner, I really like the design and the use of a bridge circuit to measure SWR and a nice load on the rig during the process. Also it provides a dummy load. Back in my FT-817 days, I had an Oak Hills QRP Wattmeter which got sold with the rigs. The QRPoMeter is a good fit and is quite accurate. Its powered by an internal 9v battery and has a very sharp LCD display. Its clearly a superior instrument.
Transformer Experimentation Board: This kit has a very handy set of components with the PC board. After learning why certain size of toroids require a certain number of turns, I decided to build the EFHW 49:1 transformer and use this with my Bayou Jumper rather than a long wire as used back in WWII. I did the winding carefully and gave it a try with a 66 ft longwire and a 30 ft counterpoise. Didn't work. Then I checked the photo and see the jumper is needed to connect the CP to the circuit. Still no joy. My antenna analyzers indicate that its not an antenna for ANY ham band. I checked everything closely and made sure I burned off the thermaleze and tinned the wires, etc. The included caps are unmarked but I measured them and chose the largest one. With or without cap, its the same. I'm at a loss on this one.
All in all, lots of fun building inexpensive projects that make ham radio fun and interesting. My hat's off to all those who design and produce these kits.
73, Larry W7DGP
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