PLEASE LEFT CLICK ON PICTURES TO ENLARGE THEM
This is a replica Paraset I constructed a few years ago. I used to manufacture Paraset keys.
I constructed this 4-1000 amplifier about 10 years ago, It's still working.
I built this Mark III Tinker Box replica transmitter to fit into my station "X"
The WESTKIT BN-1
original bn-1 My replica bn-1
I will be writing an article comparing the original bn-1 and the replica I built with performance
data, graphs, and schematics.
Along about October 2013 I purchased a Rigol DSA 815 TG. I ran through the temporary software until my 25 hours were up. It's at that time I pondered on buying the VSWR program ($500+ just for the program), that automatically gave me the VSWR ratios.
I started using the return loss chart to calculate my ratios and this worked out just fine. Since I bought the spectrum analyzer I've constructed return loss bridges from the schematics I obtained through the Internet. I must've designed 14+ circuits using different types of components (through hole and surface mount).
About the fourth or fifth circuit I decided I needed a reference point so I bought a ZFDC-20-5+ coupler from Minicircuits. This device shows a good return loss from .1 MHz to 2 GHz.
Here's a comparison of the ZFDC-20-5+ coupler and my Return Loss Bridge.
The above are details for the modification click to expand.
Hygain 18ht (hy tower) retuned
I retuned my 18 ht and here's the results
I reassembled it according to the manual and all the dimensions for the parasitic elements were done accordingly. I've got 36 ground radials measuring from 16 to 65 feet. I have one ground radial that measures 135 feet for 160 meters. After everything was assembled I decided to put my Rigol DSA 815 SG Spectrum Analyzer on it. It showed some interesting anomalies.
As you can see the majority of the peaks where the SWR is at there lowest, are outside of the ham bands.
After readjusting the parasitic elements for maximum efficiency in each band this was my final result.
This is the original and the theoretical dimensions of the 18 HT from the manual.
These are the dimensions I used, in order to achieve maximum efficiency within the ham bands for this antenna.
Please email me at <Gary (at) kf9cm (dot) com> with any comments additions for questions.