First Homebrew Baluns

ScubaJungle

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Finally made my first two homebrew baluns.

One is 2x FT240-43 for 80m-30m, for a homebrew fan dipole, the other is 2x FT240-52 for my Traffie Hexbeam.

I used G3TQXs charts for reference on turns and ferrite mix - I'm pleasantly surprised at the improvement seen on my hexbeam after installing this.
There definitely seems to be a decrease in noise, and signals seem more "concentrated" on my 7300s scope. I haven't really gotten to test out the fan dipole yet, so I can't say on that one.

I used RG178 in place of RG313, but I didn't realize how small it was. I may have to use thicker coax/wire later, but for now, I'm only running barefoot so it's no issue.
I used a combo of hot glue gun and coax putty/sealant for waterproofing the connectors/case.

Some things I learned in the process:
- It seems to be better to put the SO239 from the outside. The nuts dont get in the way of the connector, and it is easily sealed from both sides. YOu can see I learned from my mistake midway and did it the other way first, then changed it.
-Think of a way to keep the toroid held in place prior to putting the toroid in the case. For the first one, it was too late, I had already soldered the connectors and needed to figure it out, which brings to the next point
- solder the connections last! Make sure all of the nuts and such fit, then secure the braid. On the first one, I soldered the braid prior to putting it in, and had to use a Dremel to sand it down so the nuts could fit.
 

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ScubaJungle

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Nice work. If you needed a little higher power RG-316 might have been a better choice. It should handle up to about 500w SSB at 10m and more at lower freqs. Otherwise RG-142 or RG-400 is pretty standard for winding full legal limit and higher choke baluns.
Thanks - I used the videos and info you gave me a while back when building these - so I appreciate it. I must have mistaken the coax types, I was kind of surprised when I saw how tiny the RG178 was. I'm saving up some money to get an amp at the moment, and I'm eyeing the ALS-600. I think I'll be more than happy with 500-600 watts in a solid-state amp (vs 1-2kw in a tube amp), as I've been doing well with my antenna systems at 100 watts. The extra couple hundred watts would just allow me to grab those DX stations where I'm just at the noise level.

Do you have any preference out of those three coax types? Also, any personal suggestions for a ~600w solid-state amp (on the lower cost side - the KPA500 looks awesome, but is way past my budget)?

I think I'll just end up making two completely new CMCs for higher power, as the whole cost was only about $40 each. Then I'll have two lower-power ones to use in portable/mobile set-ups, like POTA or something similar. I'll have to grab one of those coax types for the new builds.
 

prcguy

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I have tons of RG-142 so that's what I use but its silver plated solid steel center conductor and it complains bitterly when winding tightly around the cores. RG-400 has a stranded center conductor and might be easier to wind but its harder to find a friendly prices.

For a 500w amp I love the SGC-500 and have two of those. Once its set up properly its bullet proof and depending on the vintage they can put out up to 700w all day long. You will need a 12V at 90A or more power supply or run it from a deep cycle battery with float charger. The ALS-600 is ok but pricy. I also have an Elecraft KPA-500 and that is beyond pricy and I would only recommend that if you already have an Elecraft radio that will take advantage of all the interface stuff.

Thanks - I used the videos and info you gave me a while back when building these - so I appreciate it. I must have mistaken the coax types, I was kind of surprised when I saw how tiny the RG178 was. I'm saving up some money to get an amp at the moment, and I'm eyeing the ALS-600. I think I'll be more than happy with 500-600 watts in a solid-state amp (vs 1-2kw in a tube amp), as I've been doing well with my antenna systems at 100 watts. The extra couple hundred watts would just allow me to grab those DX stations where I'm just at the noise level.

Do you have any preference out of those three coax types? Also, any personal suggestions for a ~600w solid-state amp (on the lower cost side - the KPA500 looks awesome, but is way past my budget)?

I think I'll just end up making two completely new CMCs for higher power, as the whole cost was only about $40 each. Then I'll have two lower-power ones to use in portable/mobile set-ups, like POTA or something similar. I'll have to grab one of those coax types for the new builds.
 

ScubaJungle

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I have tons of RG-142 so that's what I use but its silver plated solid steel center conductor and it complains bitterly when winding tightly around the cores. RG-400 has a stranded center conductor and might be easier to wind but its harder to find a friendly prices.

For a 500w amp I love the SGC-500 and have two of those. Once its set up properly its bullet proof and depending on the vintage they can put out up to 700w all day long. You will need a 12V at 90A or more power supply or run it from a deep cycle battery with float charger. The ALS-600 is ok but pricy. I also have an Elecraft KPA-500 and that is beyond pricy and I would only recommend that if you already have an Elecraft radio that will take advantage of all the interface stuff.
I didn't even know about the SGC-500 - thanks. Looks like a nice little amp, and not a bad price at all. I suppose if it weren't for the power needs, it would be a lot more popular. The deep cycle battery with the charger seems like a good idea though, and also gives you portability, which I assume is what the idea of the amp is.
I've been seeing quite a few "kit" amps lately (such as the "Mercury III"), which seem like knock-offs of the RF kits design ($4k+), and use the LDMOS parts and Motorola plans. If they were sub $1000, I'd take the chance, but at $2500, it seems like too much of a risk, even at supposedly 3kW levels. I wish I had the knowledge to build one myself, as the bare LDMOS amps are really cheap - like $700 for 3kW. Even if I only used it at 800w, it would be a deal.
 

prcguy

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I assembled a 1,200 watt 160 through 6m LDMOS amp from Victor at eb104.ru and am very pleased with it. You get a fully assembled and tested PA board that will do 1,200 watts out with 2 watts drive and a built and tested switched low pass filter board, various protection boards, etc. You have to assemble it into a box with a 48 to 60 volt 30 amp power supply and you can pick up excellent power supplies used for $75. If you buy an amplifier board Victor sends you a link to a Youtube video of him testing your specific amplifier module so you can see it working on all bands.

I have the amp setup to switch between 10 watts input or 40 watts input depending on the type of radio. Price for the kit was $900 and I met Victor in person at the Dayton Hamvention and had a nice chat with him. Out of all the LDMOS kits I think his is the best design and workmanship and also the best prices.

Victor now sells completed amplifiers, you just connect to a 48 to 60 volt supply and talk. They have auto band switching, lots of protection for the FET and work great plus they are cheap. Here is a link to his web site with kits and completed amps. List of products

I didn't even know about the SGC-500 - thanks. Looks like a nice little amp, and not a bad price at all. I suppose if it weren't for the power needs, it would be a lot more popular. The deep cycle battery with the charger seems like a good idea though, and also gives you portability, which I assume is what the idea of the amp is.
I've been seeing quite a few "kit" amps lately (such as the "Mercury III"), which seem like knock-offs of the RF kits design ($4k+), and use the LDMOS parts and Motorola plans. If they were sub $1000, I'd take the chance, but at $2500, it seems like too much of a risk, even at supposedly 3kW levels. I wish I had the knowledge to build one myself, as the bare LDMOS amps are really cheap - like $700 for 3kW. Even if I only used it at 800w, it would be a deal.
 

ScubaJungle

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I assembled a 1,200 watt 160 through 6m LDMOS amp from Victor at eb104.ru and am very pleased with it. You get a fully assembled and tested PA board that will do 1,200 watts out with 2 watts drive and a built and tested switched low pass filter board, various protection boards, etc. You have to assemble it into a box with a 48 to 60 volt 30 amp power supply and you can pick up excellent power supplies used for $75. If you buy an amplifier board Victor sends you a link to a Youtube video of him testing your specific amplifier module so you can see it working on all bands.

I have the amp setup to switch between 10 watts input or 40 watts input depending on the type of radio. Price for the kit was $900 and I met Victor in person at the Dayton Hamvention and had a nice chat with him. Out of all the LDMOS kits I think his is the best design and workmanship and also the best prices.

Victor now sells completed amplifiers, you just connect to a 48 to 60 volt supply and talk. They have auto band switching, lots of protection for the FET and work great plus they are cheap. Here is a link to his web site with kits and completed amps. List of products
Wow, $900 is something I can do.
Thank you for pointing that out, I was very hesitant to buy any of the kits, especially the lower-priced ones as I really had no idea of whether they were even real. The SGC amp looks really nice, but $900 is hard to beat on a college budget. I enjoy assembling things and love doing little kits and projects, so that is a plus for me, not a negative. I'm thinking that may the way I go now - since I do only have a 600w tuner at the moment, would it be possible to keep the amp at around 500w for the time (not sure if it has output power control, or perhaps just limit input power?)

--- Edit: actually, I see he has a 500w version for around $800. Looks like a great deal.
 
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