Test And Measurement Of RF Transformers We’ve not posted in an age. This is the reason. Read on. It is no great surprise that there is not a great deal of information about testing EFHW UnUns and other types of UnUn and baluns readily available. There are reasons; it takes time and the technical requirements …
I got a shipment of cores in today. There were 2 off FT240-43’s and 25 off FT82-43’s. Yes. All are type 43 material from Fair-rite. They were purchased in Aus from a highly reputable supplier so I believe they would be the genuine article. I wouldn’t buy them if I hadn’t already tested with them …
Suppliers Should Know Better I’ve just been looking around the internet recently and I saw some head-scratchingly poor advice and, ah, dodgy tech onfo. Seriously, I expected better from what I thought was a professional supplier of baluns. Here are some claims and my refutations. You Can’t Get Good Efficiency With QRP Designs My tiny …
I saw one of these last week on the internet. It is a beautifully packaged FT82-43 UnUn that has a 2 turn primary and 14 turn secondary, the turns are spread out and has the magical bifilar primary. It was well made and looked pretty good. There is one problem. It is very inefficient. It …
A 100W 49:1 UnUn in the palm of your hand. This looks too small to handle 100W – even to me. It is only 64mm long excluding connectors, and 33mm in diameter. Yet I’ve pushed 100W SSB into this for an hour QSO and without ill effects. The reason is that it is a high …
It’s An Addiction – Product Development The week before last I was triggered by a YouTube video that led to an internet rabbit-hole experience. On YouTube the simple 49:1 UnUn rules supreme and ‘works great’ for everyone with its lovely 1:1 SWR range across a bunch of bands. With that SWR it just must be …
Does EFHW Efficiency Matter? If you go looking at common and popular designs for EFHW UnUns on the internet they mostly follow the same general formula. You put a 2 turn bifilar primary winding onto a toroid and a 14 turn secondary so you get a 49:1 impedance transformation. The turns are spread out and …
EFHW UnUn Testing – The Tales It Tells The saying, “You can’t test quality into a product” was said to me quite a few decades ago now and to this day I still like it. With respect to EFHW UnUns it is actually rather prophetic. I’ve seen EFHW designs and kits that have efficiencies around …
Antenna Colors – Reducing Accident Hazards Just about everyone, me included, has installed an antenna with black wire. Black wire is good. Black wire is normal. BUT black wire is hard to see – particularly in poor light. So we have some color options. White – Brown – Black – Gray – Yellow – Orange. …
We shipped our first 20 EFHW Kits We’ve reserved this product for FAMPARC to sell through their club. It was a “bumpy ride” to say the least. Their first order was 10, but that sold out in 12 hours, so they increased to 15, and then a few hours later they changed to 20. Then …