Re: Adding an Antenna Port to an Ultralight


Gary DeBock
 

Great Project, John!
 
     Your success in coupling effective external antennas to the SRF-39FP and DT-200VX ultralights should give you lots of exciting TP-DX at Orcas Island.  Especially with the superb selectivity mod installed by Guy on the DT-200VX, that digital model should really come in handy around September and October.
 
     In February, a couple of DT-200VX units were modified here to receive 6.25" loopstick transplants (which greatly boosted their sensitivity), but the Icom filters provided by Guy have yet to be installed. The units were taken to Grayland on March 13th, where they received very loud TP signals from Japan, but with no selectivity improvements, they had a tricky time dodging the domestic QRM in chasing the weaker TP's.  The modified SRF-39FP (also with a 6.25" transplant) did much better selectivity-wise, splitting off NK-653, China-963 and HLCA-972 without too much trouble.  A lot of time was used trying to receive VOA-1575 on the QRM-troubled DT-200VX (only), when the SRF-39FP possibly could have nailed it.
 
     As Guy and I both discovered, the DT-200VX alignment usually favors either the low end or high end of the band, but not both.  The design is not broadbanded like the SRF-39FP, and two factory units rarely have sensitivity equal in all areas of the band.  My own "solution" was to align one transplant-enabled unit to favor the low end, and one to favor the high end.
 
     Having completed the fanatical loopstick transplant experimentation with the SRF-39FP (and hearing the 20.25" model run wild over classic DX portables in sensitivity), the DT-200VX and ICF-2010 are the next logical candidates for "mega-surgery."  If an Ultralight tinkerer can successfully transplant a 14" or 20" loopstick into the ICF-2010, it may be of some interest to the general AM-DX community (as well as restoring its proper function as a "spotting receiver" for the hot-rodded Ultralights  :>)
 
     Anyway, John, congratulations on your success, and I think both of us will have a lot of fun in the fall.  Maybe both of us can show up at Grayland on the same date, and compare the results of our divergent experimentation.
 
                                                                                            73,  Gary
 
                                                                               73,  Gary 




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