Common mode choke Recently I assembled a Common mode choke from HFkits to use with my vertical antenna that, due to space restrictions, do not have radials as counterpoise. This common mode choke should cover the HF band from 3MHz to 30MHz. A common mode choke should prevent the outer conductor from radiate. And it may prevent noise picked up from the outer conductor to reach the radio. This is how the kit after I opened the package.

I got my amateur radio license in 2017. My call sign is LB8NH. If you have not have contact with me it is because I have not been a very active amateur. In 2018 I bought a Kenwood TS820 on a junk auction. The transceiver worked when I fist tested it but after a few days it started to go inn and out. For a long time it was just collecting dust on my bench as I was to busy with other things.

Recently I bought and assembled a Elekit TU-8500 preamplifier which impressed me enough to try another Elekit kit. This time i built the Elekit TU-8200 power amplifier. Then I had finished assembling the kit and tested it I had no sound in the left channel. After some fault finding I found a missing soldering. After I corrected the missing soldering the kit worked great. It is a beautiful and great sounding amplifier.

I bought a used record player, Pro-Ject Debut Carbon, but it was without a RIAA stage so I needed a RIAA stage. Also my power amplifier at that time had just a single input and no volume control, so I wanted to be able to select between different inputs and have a volume control. I therefore decided to make a preamplifier. Since I recently had started reading about vacuum tubes I wanted to build one with vacuum tubes.

Recently I build a new set of loadspeakers called Bragi. I did not design them they are availabla as a DIY kit from Seas. Or directly from my home page. Bragi. I wanted a set of loadspeakers with litte variations in the impedance curve to use with my transformer coupled amplifier . Bragi fulfileld this criteria quite nice. I did not have 19mm plywood available, but I had 21mm. I therefore made some small changes to the box as can be seen in my modified drawing below.

I recently assembled a Vellman K4040 vacuum tube power amplifier. The amplifier works well. It is nice to have an amplifier with the full schematics and part numbers in order to do repairs. Here are some pictures of the process. It was hard taking a good picture of it fully assembled because it is so shiny. My reflections can clearly be seen. K4040 with the cabinet open. K4040 with the cabinet closed.

To complete my 5.1 loudspeaker system I designed and built a center loudspeaker. To make it easier to place the loudspeaker I designed it relativly small using two 4 inch bass-midrange elements and a tweeter. A bigger loudspeaker was not needed since my subwoofer and main front speakers can handle the low frequencies. My center loudspeaker The loudspeaker elements I tried to find as similar elements to my other loudspeakers as possible.

This is my third loudspeaker design. I wanted a subwoofer to extend the low frequency response. I am not going to play very loud nor I do not want a big box, therefor I built a relatively small subwoofer using a 10″ element. My subwofer The loudspeaker element Peerless Resolution 10 is an element witch fits well into a reasonable box. I will not go into details about how I assembled the subwoofer here.

This is the second loudspeakers I have designed and built. They are a smaller equivalent of my front speakers. I am using them as my rear speakers. The box and filters are designed the same way the front speakers was designed. Therefor I will not cover the design in details here, but I will cover the assembling. One of the loudspeakers Loudspeaker elements Since this is a two way system I had to find a tweeter and a bass-midrange to cover the whole frequency range of the loudspeaker.

This is the first loudspeakers I have designed and made. One of the loudspeakers The loudspeaker elements Since this is a two way system I had to find a tweeter and a bass-midrange speaker to cover the whole frequency range of the speaker. I decided to use the tweeter Seas H1189 27TDFC and the bass-midrange Peerless CSX 176 H. Box Calculations I have calculated the box after the formulas given in Høyttalerbok.