The AM Forum

THE AM BULLETIN BOARD => Technical Forum => Topic started by: W9ZSL on November 14, 2019, 12:54:05 PM



Title: Spacers In Over / Under 75/40 Dipole
Post by: W9ZSL on November 14, 2019, 12:54:05 PM
I scored 10 NOS, still-wrapped Johnson ceramic spacers for @20. They're about 6" long by 1/2". I have a 75 meter inverted "V" that uses Copperweld wire. I want to add a second dipole for 40 beneath it, Any suggestions for some form of clamp, bushing or stay to keep the spacers in place?


Title: Re: Spacers In Over / Under 75/40 Dipole
Post by: W1ITT on November 14, 2019, 03:09:42 PM
There were a few different versions of the ceramic line spreaders and getting a matched set nowadays is a good prize.  Most of them had a shallow groove at or near the end, in addition to the hole.  The old buzzard method of making open wire line was not to thread the spacers onto the wires, but to lay them up against the groove and use a short tie wire through the hole and wrapped a few times around the main wire.  It was considered good practice to solder these connections.  That way, nothing can slip or slide and it all works well when airborne.  Using clips or other devices would add weight to the assembly and that's not what you want.

73 de Norm W1ITT


Title: Re: Spacers In Over / Under 75/40 Dipole
Post by: KK4YY on November 14, 2019, 03:29:14 PM
There were a few different versions of the ceramic line spreaders and getting a matched set nowadays is a good prize.  Most of them had a shallow groove at or near the end, in addition to the hole.  The old buzzard method of making open wire line was not to thread the spacers onto the wires, but to lay them up against the groove and use a short tie wire through the hole and wrapped a few times around the main wire.  It was considered good practice to solder these connections.  That way, nothing can slip or slide and it all works well when airborne.  Using clips or other devices would add weight to the assembly and that's not what you want.

73 de Norm W1ITT

From the "Handbook"...


Title: Re: Spacers In Over / Under 75/40 Dipole
Post by: KA0HCP on November 14, 2019, 05:23:20 PM
Use a somewhat heavy Solid wire for the tie-wire.


Title: Re: Spacers In Over / Under 75/40 Dipole
Post by: Steve - K4HX on November 16, 2019, 06:02:52 PM
How many spacers to you plan to use. Those ceramic spacers are quite a bit heavier than plastic ones.
 I used the plastic ones on a 80/40 meter dipole at my previous QTH. They were held in place with a dab of epoxy.

(http://www.amwindow.org/misc/newant/40End.jpg)

(http://www.amwindow.org/misc/newant/WireSky.jpg)
AMfone - Dedicated to Amplitude Modulation on the Amateur Radio Bands