[sarcmembers] Re: Hardline needed...

  • From: n6vmo@xxxxxxxxx
  • To: sarcmembers@xxxxxxxxxxxxx
  • Date: Thu, 10 Jul 2008 11:55:02 -0700

Hello Eric, Bill and George,
 
Thank you all for your help.
 
Agreed, the roof mounting is not desirable for both the Air Force's sensitivity and the ability to easily adjust for azimuth and elevation. Although it would look really cool sitting up there...
 
Bill, is your source of LDF5-50 easier to get to than the wealth of LDF5-50 located in dark, damp bowels of the SLC-6 electrical tunnels? Eric your permission to harvest some abandoned LDF5-50 sounds very attractive. Even if it is decided to stick with the current HL, I would be willing to assist in mining some LDF5-50 for the club's use.
 
Yes, 80' is the minimum and the current length for the present dish and equipment locations. On 144Mhz the LDF4-50 works fine and the equipment needs to be operated from the radio room because it requires 220VAC service. But, a length LDF5-50 would enhance the 2 meter operations as well.
 
However, I have been thinking that EME operations are limited to once or twice a month, at which time the moon is at a relatively high declination.  The original thoughts on the dish position were to use it for EME and some terrestrial experiments. So, it had to be able to track the moon from horizon to horizon. But I have abandoned those thoughts for a couple of reasons.  One, no one uses circular polarization during terrestrial 1296MHz operations. Two, small EME systems need the gain that the earth provides at low moon elevation angles. Once the moon reaches >35degs in elevation, those ground gains are minimized and small stations suffer. So, small EME station operations at moonrise and moon-set are preferred.
 
That led me to other possible solutions to discuss with the membership.  Maybe some new club buisness for this Saturday's meeting?
 
1. Can the dish be repositioned to the northwest corner of the clubhouse building, either on the blacktop or grass. In that location, the 1296MHz EME equipment could temporarily be located inside near the meeting room double doors and run a greatly reduced length of feed-line out to the dish. The 1296Mhz equipment needs only a 110VAc source and the equipment can be easily disassembled and returned to its storage location after each operation. (Need to better define this storage location)
 
2. Can the dish be repositioned to the southeast of the clubhouse building, either on the blacktop or grass? In that location, the 1296MHz EME equipment can remain in the radio room and a greatly reduced length of feed-line could be run outside via the wall penetration. This location offers horizon to horizon tracking of the moon in the event the small 1296MHz EME station becomes a large 1296MHz EME station.
 
In all cases above, it is clear that a better feed-line is needed. But, if that better feed-line can be shortened in length by repositioning the dish, it becomes an even better situation.
 
Thanks for every-ones help. See you all at this Saturday's meeting.
 
73
 
John
N6VMO
-------- Original Message --------
Subject: [sarcmembers] Re: Hardline needed...
From: "Eric Lemmon"
Date: Wed, July 09, 2008 8:40 pm
To: <sarcmembers@xxxxxxxxxxxxx>

John,

Roof mounting is not an option, since it would compromise the integrity of
the roof seal. The Air Force is very sensitive about tenants damaging the
roofing on Government-owned buildings.

There are still many miles of abandoned LDF5-50 Heliax in the cable tunnel
at SLC-6. I already have permission to salvage more of that cable, but have
not exercised the option. Is 80 feet an accurate figure?

73, Eric Lemmon WB6FLY


-----Original Message-----
From: sarcmembers-bounce@freelists.org
[mailto:sarcmembers-bounce@freelists.org] On Behalf Of John Maetta
Sent: Wednesday, July 09, 2008 8:03 PM
To: sarcmembers@freelists.org
Subject: [sarcmembers] Hardline needed...

Hello,

Tonight, after some testing of my 1296MHz EME system, I noted the following.
The 280W output of the amplifier was reduced to 160W by the time it reached
the antenna feed.

I am currently using an 80' run of Andrew LD4-50 1/2" hardline from the amp
to the antenna feed. This length of HL keeps my operating position and
equipment inside the clubhouse radio room.
But, this 2dB transmit power loss is not tolerable and of course effects my
receive signals too.

One solution is to move the amplifier and transceiver closer to the antenna.
This solution will work, but will cause me to have to operate out of doors.


The second is to locate the dish closer to the indoor operating position.
(On the clubhouse roof affords the best tracking of the moon from horizon to
horizon and cuts the coax run by half. But requires approval of the
board/members)

The third solution is to upgrade to a less lossy hardline such as 7/8" or
larger. This is the easiest solution if I can locate a local source.

Does anyone know where I can locate a source for new or used hardline in
this size and length? I know cellular and CATV companies may have some
short lengths laying around unusable.
Most amateurs, that have this type hardline available, are offering it as
pick up only, because of its size. So this is why I putting out local notice
first.

Thanks,

73

John


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