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Total 1321 documents matching your query.

321. [TowerTalk] HAM IV rotor / mast slipping / Slipp-Nott (score: 1)
Author: "Jim Thomson" <jim.thom@telus.net>
Date: Fri, 6 Apr 2012 07:07:55 -0700
The Slipp-Nott at first seems like a good idea, but as I found it can put too much stress on the rotor U-bolts. If I had thought to double-nut the U-bolts, that should have prevented the nuts from be
/archives//html/Towertalk/2012-04/msg00095.html (12,828 bytes)

322. [TowerTalk] Coax (score: 1)
Author: "Jim Thomson" <jim.thom@telus.net>
Date: Sun, 8 Apr 2012 21:01:22 -0700
There's nothing magic about LMR400 that justifies its cost for operation on the HF bands. For use below 100 MHz, Davis 213 is as good, of good quality, and a lot less expensive. For more about coax,
/archives//html/Towertalk/2012-04/msg00116.html (11,462 bytes)

323. Re: [TowerTalk] Coax (score: 1)
Author: "Jim Thomson" <jim.thom@telus.net>
Date: Sun, 8 Apr 2012 23:49:22 -0700
...snip... You end up with 3 x choices. (a) increase the ...snip... Actually, that only makes up the transmit side - that S3 signal just above the noise goes down 3 dB too. I think fighting for the R
/archives//html/Towertalk/2012-04/msg00121.html (9,525 bytes)

324. [TowerTalk] Coax (score: 1)
Author: "Jim Thomson" <jim.thom@telus.net>
Date: Mon, 9 Apr 2012 06:04:21 -0700
RG213 is not a spec, it's a very broad generic description. There are RG213s built with thin copper braid and others with heavy copper braid. The loss in cable is a direct function of how much copper
/archives//html/Towertalk/2012-04/msg00125.html (11,691 bytes)

325. Re: [TowerTalk] Coax (score: 1)
Author: "Jim Thomson" <jim.thom@telus.net>
Date: Mon, 9 Apr 2012 07:28:14 -0700
Jim, the example compares 200ft of LMR400 to RG213. The stated difference is .358 dB/100ft for a total of .716 dB. That is a power ratio of 1.179 or 100w vs 117.9w. That is easily measured with a bir
/archives//html/Towertalk/2012-04/msg00130.html (12,782 bytes)

326. [TowerTalk] Anchor bolts for LM470 (score: 1)
Author: "Jim Thomson" <jim.thom@telus.net>
Date: Mon, 16 Apr 2012 02:26:22 -0700
It is not necessary to coat the anchor bolts with anything. When the steel is encased in concrete it cuts of the supply of Oxygen so it doesn't rust. If steel rusted inside concrete you would have to
/archives//html/Towertalk/2012-04/msg00280.html (15,078 bytes)

327. [TowerTalk] Coax (score: 1)
Author: "Jim Thomson" <jim.thom@telus.net>
Date: Mon, 16 Apr 2012 03:18:26 -0700
More like 115 or 120W vs 100W .. 5% accuracy is probably more realistic. As an example, the Telepost LP100 manual (which I happen to have here) says 5% worst case absolute, 3% typical, but doesn't sa
/archives//html/Towertalk/2012-04/msg00281.html (11,162 bytes)

328. [TowerTalk] Balun Recommendation (score: 1)
Author: "Jim Thomson" <jim.thom@telus.net>
Date: Mon, 16 Apr 2012 04:11:21 -0700
Some designs here: http://www.karinya.net/g3txq/chokes/ 8 turns on a FT240-31 core is good for 20m thru 10m - it gives >2k Ohm choking impedance across the range and is predominantly resistive. Steve
/archives//html/Towertalk/2012-04/msg00282.html (9,717 bytes)

329. [TowerTalk] Balun Recommendation (score: 1)
Author: "Jim Thomson" <jim.thom@telus.net>
Date: Tue, 17 Apr 2012 00:04:27 -0700
Jim, you are looking at the elephant through a pin hole. You build and run big power amps, and your measure of the effectiveness of a choke is that there it doesn't blow up. A string of beads on coax
/archives//html/Towertalk/2012-04/msg00316.html (12,345 bytes)

330. [TowerTalk] Anchor bolts for LM470 (score: 1)
Author: "Jim Thomson" <jim.thom@telus.net>
Date: Tue, 17 Apr 2012 01:23:29 -0700
Institution (ACI) 318 design specifications for reinforced concrete to use hooked (J) anchor rods in tension situations without reducing the tension capacity significantly for hooked anchors on accou
/archives//html/Towertalk/2012-04/msg00317.html (10,268 bytes)

331. [TowerTalk] Anchor bolts for LM470 (score: 1)
Author: "Jim Thomson" <jim.thom@telus.net>
Date: Tue, 17 Apr 2012 07:04:04 -0700
I'm not sure why you would need to tighten the nuts that much. Once they're cast in concrete, nothing is going anywhere. It's not like the lower nut is going to magically fall off the end of the bolt
/archives//html/Towertalk/2012-04/msg00324.html (9,280 bytes)

332. [TowerTalk] Balun Recommendation (score: 1)
Author: "Jim Thomson" <jim.thom@telus.net>
Date: Wed, 18 Apr 2012 02:25:55 -0700
Following up on Jim Thomson's love for strings of beads. It's quite instructive to study the Fair-Rite data sheets for representative parts. Go to the link below and enter the part numbers, then go t
/archives//html/Towertalk/2012-04/msg00339.html (12,269 bytes)

333. [TowerTalk] Balun Recommendation (score: 1)
Author: "Jim Thomson" <jim.thom@telus.net>
Date: Thu, 19 Apr 2012 10:53:43 -0700
I don't buy your analysis, but I don't have time to pick it apart. :) 73, Jim K9YC worse. If the choke is mainly resistive, and its only 1-2k, then toss in high swr.... and then toss in high power an
/archives//html/Towertalk/2012-04/msg00358.html (8,740 bytes)

334. [TowerTalk] Balun Recommendation (score: 1)
Author: "Jim Thomson" <jim.thom@telus.net>
Date: Mon, 23 Apr 2012 03:03:18 -0700
While common mode current may be a bit of a misnomer, it is accurate in that the effect of "outer shield current" is identical to that of common mode current in a balanced system because of the "pin
/archives//html/Towertalk/2012-04/msg00464.html (12,253 bytes)

335. [TowerTalk] Balun Recommendation (score: 1)
Author: "Jim Thomson" <jim.thom@telus.net>
Date: Mon, 23 Apr 2012 03:21:58 -0700
I'm very short of time, because I'm entertaining house guests, about to take them out to dinner, and leaving in the morning for the Visalia DX/Contesting convention. The thing that is WRONG about Ste
/archives//html/Towertalk/2012-04/msg00465.html (10,929 bytes)

336. [TowerTalk] Balun Recommendation (score: 1)
Author: "Jim Thomson" <jim.thom@telus.net>
Date: Tue, 24 Apr 2012 02:19:20 -0700
You apparently still don't understand the Pin One Problem. &&&&& Oh I fully understand the Pin 1 problem alright. I wish that were true. While things have gotten a lot better since Neil Muncy first p
/archives//html/Towertalk/2012-04/msg00521.html (17,293 bytes)

337. [TowerTalk] WHICH ROTOR TO USE? (score: 1)
Author: "Jim Thomson" <jim.thom@telus.net>
Date: Tue, 8 May 2012 04:44:16 -0700
The Orion 2800 was one of the other rotators I was trying to think of which I believe uses a double worm gear drive and pulse direction indication. just a single worm gear drive. While the upper clam
/archives//html/Towertalk/2012-05/msg00115.html (13,695 bytes)

338. [TowerTalk] cell Tower broadcasts (score: 1)
Author: "Jim Thomson" <jim.thom@telus.net>
Date: Wed, 30 May 2012 03:25:34 -0700
Mickey You're in the working arena and I have no doubt you know what you are doing. You've been in it for quite a few years. It's all common sense. Can you point me to anyone in the governmental regu
/archives//html/Towertalk/2012-05/msg00384.html (12,372 bytes)

339. [TowerTalk] Wall thickness? (score: 1)
Author: "Jim Thomson" <jim.thom@telus.net>
Date: Sun, 15 Jul 2012 15:16:19 -0700
Howdy - I'm fixing a couple of broken F12 elements and need to know what the typical wall thickness is for normal aluminum antenna elements. It seems to me that 0.058" is a number I've seen before bu
/archives//html/Towertalk/2012-07/msg00150.html (8,917 bytes)

340. [TowerTalk] Mast slipping (score: 1)
Author: "Jim Thomson" <jim.thom@telus.net>
Date: Mon, 23 Jul 2012 02:10:41 -0700
Grant sez... There is no benefit to having the saddle extend further than the DXE single saddle clamps as there is no force from the U-bolt to provide clamping force. If more clamp is needed, there a
/archives//html/Towertalk/2012-07/msg00258.html (10,822 bytes)

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