These are ~49:1 ratio (~2500:50 Ohms) UNUN transformers for EFHW antennas, just pick one and add half wave long wire for the frequency of interest. Note that it will also work on its harmonics for example 3.5 MHz x 2,3,4..
NOTICE! We are experiencing increased sales due to the COVID-19 Virus situation but we assure you that we are shipping on time and there is no need for inquiries about shipping via our Contact/Ticket Support page. There is plenty of products and materials in stock. Dismiss