[TowerTalk] Hy-Gain HG-70 HD tower

[Mike Ryan]

Don, MFJ does NOT sell the towers. ONLY the base for the tower...the rebar 
base and the ears for mounting the tower are attached/welded on. Any parts 
for the tower must be obtained from after market sources or from other 
surplus HG series towers. I verified this in person with the reps from MFJ 
at the Orlando Hamfest earlier in the year. I told them that a PICTURE of 
the tower appears on their website. They looked at each other and were 
'surprised' or so it seemed and said they would have to see about getting 
that removed from their webpage. I would bet they STILL have that photo 
there though..who knows.  But, unless something has drastically changed up 
there you can only buy the base from them, which I think sells for about 
$150 plus truck freight charges to deliver.  It is heavy...
  When you look to change those bearings, take a close look at the 'pins' or 
shafts that the pulleys ride on. If they are worn, I would not use them 
again. They will just wear out the brass sheaves that much quicker as they 
pulley will not ride perpendicular to the pin. I would suggest drilling out 
the holes were they mount and put a stainless bolt through there.  I just 
don't think you will find those galvanized pins any place unless you have 
them made for you at a machine shop. They are held in place by cotter pins 
which scares me a little anyway.
   I am using the 4" pulleys from McMaster Carr. They do not appear to be 
galvanized and I am sure their longevity will be expectedly short. But for 
less than $10 a copy I can live with that for now.  I have not looked at 
them since the spring but had put them in back in January when I replaced 
the cables. Time to have another look to be sure. The Florida environment 
here is not kind to metals outside. US Towers sells a MUCH hardier pulley 
with roller bearings for about $100 per copy. However, I don't think they 
sell a 4" copy of this. A 5" pulley is not going to fit.  Your tower uses 
4". The top cable was originally a 3/16" as is mine now, though I have seen 
a number of these towers where the user simply changed that top cable to a 
1/4" 7/32 like the others below.  The thinking is to use galvanized cable 
rather than stainless as it doesn't crush as easily and has a slightly 
higher breaking strength.  Also have seen a TB-3 ROHN bearing replace the 
stock thrust bearing as I have done but be careful to get the bearing 
CENTERED on the top before drilling the holes.  Good luck and let us know 
here what you do to refurbish the tower and where you got your parts, 
     - Mike

-----Original Message----- 
From: Big Don
Sent: Saturday, August 24, 2013 10:03 AM
To: Nick Pittner
Cc: towertalk at contesting.com
Subject: Re: [TowerTalk] Hy-Gain HG-70 HD tower

We picked-up an at-least-third-hand Tri-Ex 3-54 crankup with a bad sheave
in 1975. Airplanes use a lot of sheaves/cables for control systems. Took
the old sheave to local airport repair business where they had a bin full
of used sheaves, many sizes, and picked out one for a couple bucks that was
a close enough fit...probably came out of a DC-3 or Cessna, something like
that, was much better quality than the original. Likely wouldn't want to
pay new prices but aviation rules require decommissioning a lot of
perfectly good stuff after so-many flight hours. That same tower is still
up today, used over the years with 2-el HFquad, VHF, WX stn and various
antenna experiments.

Depending on your level of desperation, of course...

Don  N7EF


On Sat, Aug 24, 2013 at 4:40 AM, Nick Pittner <Goodsonrd at netwalk.com> 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
>
>
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