Aerial-51 Model 404-ROK
The 404-ROK is a purpose-designed modified version of the 404-UL. It was created especially for the IOTA Expedition to Rockall Island (MM0UKI).
The so-called "island" is shown here on the right. It is actually just a Rock sticking out of the ocean, not an island.
There is no possibility to guy a mast on top of the island. Two Spiderbeam fiberglass "Mini-Poles" will be extended horizontally from the rock in opposite directions.
Although the standard 404-UL has the electrical characteristics needed for the expedition, it is not physically strong enough to endure the harsh weather conditions experienced on the Rock. Thus, this ruggedized version of the 404-UL was created: "404-ROK"
The balun enclosure and balun itself is identical to that of the 404-UL. Everything else has been built of sturdier material.
The coax attached is just a short stub of M&P MIL-SPEC RG-58. The PL-259-6 is Teflon-insulated with gold-plated contacts.
The feedline is a 6 meter length of M&P MIL-SPEC RG-58.
The wire is twice as thick and has 5x the breaking strength of the wire used in the standard 404-UL. In attition, the outer jacket of the wire is of Heavy Duty Polyethene, which is much more resistant to damage when rubbing against tree-limbs (or the Rock) than ordinary Polyethene used in most other antenna wire.
The poles will probably have to be mounted horizontally because there is no posibility to guy them on the Rock.
We are unable to predict what effect this awkward configuration will have on the SWR or performance of the antenna.
Clearly an antenna tuner will be needed to present a low SWR to the transceiver.
I am unable to upload large videos from my computer to this web site, so I have published the videos of the 404-ROK mounted onto a Spiderbeam telescoping fiberglass 10m Mini-Pole and onto a Spiderbeam 12m telescoping fiberglass pole here: 404-ROK Videos