[TowerTalk] Hy-Gain HG-70 HD tower

[Glenn Rattmann]

A little history lesson... I apologize if it's a TT dupe.

(Telex) Hy-Gain got into the tower business in the early eighties 
when a former Tri-Ex sales manager went to work for them in 
Nebraska.  The HG-70HD is in the same general class of tower as the 
Tri-Ex LM-470-- not identical, but similar.

I think it's well known that Karl, of Tashjian Towers today, was an 
engineer for many years at Tri-Ex, back in the day (Karl is not the 
former Tri-Ex employee I mentioned above).  Tashjian builds an 
updated, modern LM-470 today and these are excellent towers.

If I needed to rebuild an HG-70 tower, I would contact Karl at 
Tashjian.  But first, without ambiguity, measure the diameter of the 
cable(s), the diameter and maximum thickness of the sheaves; and the 
diameter and lengths of the sheave bolts or pins.  Note details such 
as whether the pin is a flathead, sockethead screw, and so forth.  I 
would also note the exact clearance available between pairs of 
sheave-mounting plates.  Send the list of what you want to buy, along 
with the measured data (don't guess) to Karl and let him tell you if 
his sheaves and some of his spare parts will do the job for 
you.  Except for the sheaves themselves, most of what you will need 
is also available as standard industrial grade hardware.

As to Nylon sheaves, on crankup towers... what are the magical 
properties of them that would make a tower owner consider 
substituting them in place of  OEM steel or machined aluminum 
sheaves?  I don't see Nylon sheaves on the UST or Tri-Ex or Tashjian 
towers I have seen.  Would someone on this mail list install Nylon 
wheels on his car, if the OEM steel wheels were to wear out?
Just wondering.

--Glenn K6NA
PS- To Nick's question re thrust bearing:  Last year an HG-54 owner 
and I tried to find a bearing to match the Hy-Gain bolt pattern on 
his top-plate.  Eventually he just settled on a decent Chinese 
bearing available on the Internet ($45 range), and I drilled new 
holes in the tower top plate.

At 04:40 AM 8/24/2013, you wrote:
>I have a Hy-Gain HG-70HD tower, new in 1985.  I'm in the process of 
>refurbishing it and would like to replace the cable sheaves and 
>related hardware as part of the process, but am unable to locate a 
>source for those items.  MFJ still sells the towers but apparently 
>does not sell the parts and they have not been helpful.  Does anyone 
>have information as to where I can find these parts or sufficient 
>information that I could have new ones made in advance of 
>disassembling the tower?  I'm also looking for a thrust bearing 
>assembly for the tower.  Any information would be most 
>appreciated.  Thanks for your help.
>
>Nick, K8NAP, goodsonrd at netwalk.com