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Reviews For: Elecraft BL1 150-W, 4:1 or 1:1 Balun

Category: Antenna parts, accessories, incl. baluns, hardware, etc.

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Review Summary For : Elecraft BL1 150-W, 4:1 or 1:1 Balun
Reviews: 9MSRP: 25
This highly-efficient 4:1 balun (1:1 with alternate winding) can handle up to 150 watts, yet is very small (just 1.5 x 3"), making it an excellent choice for both home and field use. It uses a special winding technique to reduce losses and extend the useful range, resulting in an SWR of less than 1.2:1 from 500 kHz to 55 MHz. It includes rugged screw terminals for the balanced output as well as ground.

The BL1 is a kit -- one of several inexpensive kits in Elecraft's "mini-modules" line. The builder can package the finished PC-board module in an enclosure if required, or use the supplied rubber feet on the PC board itself.
Product is in production
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# last 180 days Avg. Rating last 180 days Total reviews Avg. overall rating
AD5X Rating: 2005-05-24
Flexible and inexpensive Time Owned: 0 to 3 months.
Very reasonably priced and flexible balun. I made mine more flexible by adding a DPDT slide switch to switch between 1:1 and 4:1. I also replaced the BNC connector with a UHF connector so it would connect easier to my IC-703. Details at
N2WN Rating: 2005-05-24
Excellent and Adaptable Time Owned: 3 to 6 months.
I bought several of these for use with and without the board. Primarily I use them as 1:1 on my vertical antennas (1/4+ wave on 80 and 40). They fit neatly into my matching box at the antenna bases. Better than having coils of coax current baluns! Very easy to construct.
NO9E Rating: 2005-02-27
Smart design but real losses Time Owned: 6 to 12 months.
This balun has a smart design where one can plug it in directly to K2 (or another radio) and have wires attached to the other side. No extra connectors or wires to carry...

My K2 tunes better with the balun. If tuning with wires attached to extreme ends is unsuccessful, changing to one wire in the middle connector works almost always.

One wonders when better tuning with the balun is due to its transforming action, when due to changing the impedance to something else, or when due to high losses at high impedances. As the previous review stated, the balun is getting hot on many bands at 100W particularly with random-length antennas.

It is hard to construct a balun that would have low losses for a wide range of impedances and different levels of balance. Most likely, such a balun would be much larger than BL1. It is easy to make a good balun for a 50 Ohm load.

When I feel that losses with BL1 are 50% or higher, I use an external manual tuner and another balun (10 turns of RG-174 on a core) between the tuner and the radio. Even at 100W this balun never gets warm. But of course such a setup is less convenient than the built-in tuner and BL1!
KU4UV Rating: 2005-02-27
Excellent Kit! Time Owned: 0 to 3 months.
I just recently purchased this 4:1 balun kit because I wanted a way to feed some dipoles that I had constructed with 450 Ohm ladder-line instead of coax. I read the reviews here on eham and thought that the kit looked like what I needed. Since I didn't plan on running more than 100 Watts, I really didn't want to spend a whole lot of money on a high power balun. I plan on using this balun for Field Day operation and for feeding the dipoles I have in my apartment attic. The kit took all of about 30 minutes to complete. I would recommend this kit to almost anyone with basic soldering skills. It would be a great kit for beginning ham classes as well. It is kind of hard to screw up this kit since it only has about 5 components to solder. The kit basically consists of winding a couple of 10-inch lengths of twisted pair cable through a couple of holes in an iron core, soldering a BNC connector, and soldering three thumb screw connectors. The cable looks identical to 18 gauge thermostat cable you can find at almost any hardware store. After completing the balun, I hooked it up to my 450 Ohm ladder-line fed 40 meter dipole through my MFJ 902 antenna tuner. The balun works great, and I am able to load the dipole on several different bands. The only thing I noticed was the balun tends to get pretty hot after running 100 Watts through it for several minutes, especially when I am operating CW. The balun is rated for up to 150 Watts, so I wasn't totally surprised that it beacame quite hot after a period of time. I noticed the SWR also went up when the balun got hot. I found a simple and cheap solution to this problem that works great. I purchased a small 12VDC fan motor at my local Radio Shack and Velcroed it to the balun core. I also bought an 8 AA battery holder to power the fan motor. I use rechargable batteries to keep the cost down. The fan keeps the balun cool, even with 100 Watts, and it also keeps the SWR down. Problem solved. This balun should be great for QRP field operating. Hats off to Elecraft once again for a great kit!
W9OY Rating: 2004-09-28
Add a switch and it would be even better Time Owned: 0 to 3 months.
I built one of these as I am playing with a small windom for QRP portable. It is a great little balun. One thing I would like to see added is a DPDT switch to switch the impedance ratio between 4:1 and 1:1. I would be easy enough to add to the circuit board and a slide switch would be good enough probably even for 150W, certainly it would work for QRP. It might add a couple bucks to the cost but the added versitility would be worth it.

I also would like to see a male BNC plug available as opposed to the supplied female. Its very easy to make open wire line out of some wire and a roll of 3/4 inch wide tape which you can connect to the balun on the back of the rig. It's not so easy to find a male to male BNC adapter. Those are personal preferences and in no way reflect on the excellent quality of this device.
KX7R Rating: 2004-07-07
Excellent Time Owned: 0 to 3 months.
Up to the usual high Elecraft design standards for form and function. My SWR on 46' doublets (fed with 450 ohm ladder line and 10' of RG8X from balun to radios) was lower on all bands (1.2 to 1.0, typical with K2 and K1 ATUs) compared to my homebrew 4:1's built on T200 cores. The design is also optimal for portable use.
W2XS Rating: 2004-06-30
Great! Time Owned: 3 to 6 months.
The other day, I went to the beach with my KX1 QRP rig. Using a 20-foot SD20 pole as a support, I put up a 42-foot wire and counterpoise system. Results were so-so. Then I took down the wire and put up a 40m doublet fed with cheap Radio Shack twinlead. The ends of the doublet were tied down into the sand with tent stakes. The SD20 was supported by a PVC surf fishing rod holder stuck in the sand ($5.99 at the local Bait and Tackle shop) which works great. Using the interal tuner of the KX1 and the Elecraft BL1, I got a perfect match and received great signal reports on 40m and 20m. (I didn't have time to try 30m). The wire is a good portable antenna for backpacking, etc., but the doublet and balun combo is a better performer on all bands. The only issue now is that the pole leans a bit with the doublet hanging from it. Maybe I'll try a painter's extension pole next.
KQ9L Rating: 2004-06-30
Very good performer. Time Owned: 3 to 6 months.
I've used the Elecraft balun for at lease 6mo now. I can say that the device works very well. I have compared it side by side with my other homebrew baluns and the BL1 seems to allow my rigs to tune up easier and receive better signals (don't ask me how!). I also seem to get out a little better, perhaps there are less lossed with the binocular design VS the traditional round torroidal designs. One way or another, a great little device and super easy to build.

AI4BJ Rating: 2004-06-30
Great performer Time Owned: 0 to 3 months.
After experimenting with various random wire antennas for portable QRP ops and being less than thrilled with the results, I decided to try a 40m doublet. I picked up a BL1 at this year's Hamvention, and put it together in less than 30 minutes.

A few days later I gave it its first field test. I connected my homebrew ladderline to the balanced inputs of the BL1 and a short length of RG58 between the BL1 and my K2. I quickly ran the K2's built-in ATU and easily achieved a 1.1:1 SWR match on all bands (80-10m). Well, I also used to get good matches with my random-wire antennas and that didn't necessarily translate into good Tx performance, so I was not yet convinced. I switched to the 20m phone band and answered an EA station calling CQ. Bingo! An instant reply and a 57 report. I worked several more DX stations in the next hour, all reporting my signal as 55 to 59.

I've used the same doublet/BL1 combo on many field trips since, and have been completely delighted by their performance. I've called CQ myself several times and had DX stations reply that were barely above the noise level. Now *that's* a nice problem to have!

I used the same antenna/balun combo for Field Day with my K2 in its QRO configuration, and obtained excellent results on 80 through 15 meters. (I did not try 10m.) I'm now so completely sold on the advantage of balanced feedlines that I intend to buy a second BL1 and upgrade the permanent dipole at my home QTH from coax feed to ladderline.