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1. Re: [TowerTalk] Topband: Inverted L Tuning Question (score: 1)
Author: "DAVID CUTHBERT" <telegrapher9@gmail.com>
Date: Fri, 5 Dec 2008 03:03:00 -0700
Dick, I ran some simulations. There is very heavy coupling to the tower. That's not such a bad thing. The tower current is 180 out-of-phase with the inverted-L current. The GND return current is the
/archives//html/Topband/2008-12/msg00055.html (11,005 bytes)

2. Topband: Great Salt Lake (score: 1)
Author: "DAVID CUTHBERT" <telegrapher9@gmail.com>
Date: Mon, 8 Dec 2008 20:45:20 -0700
160 meter QRP effort: The Great Salt Lake of Utah is indeed great. With a conductivity nearly 4X that of sea water it provided a great ground for a balloon vertical. And that with nothing more than a
/archives//html/Topband/2008-12/msg00104.html (7,284 bytes)

3. Topband: source for Beverage resistors (score: 1)
Author: "DAVID CUTHBERT" <telegrapher9@gmail.com>
Date: Sat, 27 Dec 2008 11:31:17 -0700
Many have had Beverage termination resistor fail due to nearby lightning strikes. These parts are available at Digikey (digikey.com). This component is a bulk ceramic resistor capable of absorbing 14
/archives//html/Topband/2008-12/msg00244.html (7,532 bytes)

4. Topband: small antennas (score: 1)
Author: DAVID CUTHBERT <telegrapher9@gmail.com>
Date: Sat, 31 Jan 2009 06:45:03 -0700
How many of you operate topband with small antennas? Perhaps we can get a dialog going on how to do this successfully. I presently use a 22' top loaded vertical that will soon grow to 33'. For contes
/archives//html/Topband/2009-01/msg00338.html (6,594 bytes)

5. Re: Topband: Common mode chokes (score: 1)
Author: DAVID CUTHBERT <telegrapher9@gmail.com>
Date: Sat, 4 Jul 2009 19:24:26 -0600
Very good. Another experiment would be to ground the coax shield 20' from the antenna as you did but with no ferrite beads. I suspect you will see similar results. Yes you have a 108' dipole comprise
/archives//html/Topband/2009-07/msg00011.html (10,435 bytes)

6. Re: Topband: Antenna Question (score: 1)
Author: DAVID CUTHBERT <telegrapher9@gmail.com>
Date: Sat, 4 Jul 2009 19:34:38 -0600
The loss is quite small with the small wire. Running 100 W the loss going from #12 to #26 wire is about 4 watts. I would not bother with a balun. It will work fine without it and what's a little feed
/archives//html/Topband/2009-07/msg00012.html (10,010 bytes)

7. Re: Topband: Gas well pump motor (score: 1)
Author: DAVID CUTHBERT <telegrapher9@gmail.com>
Date: Tue, 7 Jul 2009 06:29:32 -0600
Art, what is the nature of the noise? Do you hear signals every 300 Hz or are they spaced further, such as 20 kHz? The reason I ask is to determine if the motor controller is a simple triac OFF/ON de
/archives//html/Topband/2009-07/msg00024.html (13,300 bytes)

8. Re: Topband: "Center-tapped" common mode choke (score: 1)
Author: DAVID CUTHBERT <telegrapher9@gmail.com>
Date: Tue, 7 Jul 2009 06:42:13 -0600
With this arrangement - beads,GND, beads - the 20' of coax between the whip and the GND connection continues to operate with the whip as one half of a dipole. The whip presents a high impedance to th
/archives//html/Topband/2009-07/msg00025.html (9,347 bytes)

9. Re: Topband: Helically Wound Vertical (score: 1)
Author: DAVID CUTHBERT <telegrapher9@gmail.com>
Date: Wed, 15 Jul 2009 05:03:14 -0600
Trent, the vertical will outperform the loop at 8'. I can send you plans for a vertical that works on 160, 80 and 40 meters. Simply feed with coax and it covers 20 kHz on 160 meters, 50 kHz on 80 met
/archives//html/Topband/2009-07/msg00048.html (8,991 bytes)

10. Re: Topband: Helically Wound Vertical (score: 1)
Author: DAVID CUTHBERT <telegrapher9@gmail.com>
Date: Wed, 15 Jul 2009 05:22:22 -0600
Trent, another solution that works well, is relatively inexpensive, and uses off-the-shelf components is the Hustler 5BTV vertical. It works on 10, 15, 20, 40, and 80 meters. Add a DX Engineering top
/archives//html/Topband/2009-07/msg00050.html (9,964 bytes)

11. Re: Topband: HELICALLY WOUND VERTICAL (score: 1)
Author: DAVID CUTHBERT <telegrapher9@gmail.com>
Date: Thu, 16 Jul 2009 06:56:58 -0600
Craig you are right. A helical vertical will be out performed by a top loaded vertical. The top loaded short vertical will have higher radiation resistance resulting in a better signal. Designing and
/archives//html/Topband/2009-07/msg00059.html (9,426 bytes)

12. Re: Topband: Helically wound vert (score: 1)
Author: DAVID CUTHBERT <telegrapher9@gmail.com>
Date: Sun, 19 Jul 2009 09:35:15 -0600
For the 5BTV on top band the radiation resistance of the 22' top loaded vertical is about 3 ohms. The RM80S "resonator", or top loading inductor loss is 20 ohms (that is high). Given a GND loss resis
/archives//html/Topband/2009-07/msg00077.html (8,259 bytes)

13. Re: Topband: T - vertical improvement (score: 1)
Author: DAVID CUTHBERT <telegrapher9@gmail.com>
Date: Wed, 22 Jul 2009 05:38:43 -0600
The radial system you have will be fine. What you give up is matching simplicity. The T will need a base series capacitor as a minimum and an L-network if you like a 1:1 VSWR. At 1.5 kW the 370 pF ca
/archives//html/Topband/2009-07/msg00094.html (8,433 bytes)

14. Re: Topband: T - vertical improvement (score: 1)
Author: DAVID CUTHBERT <telegrapher9@gmail.com>
Date: Fri, 24 Jul 2009 08:47:53 -0600
T-vertical, 10 kV? It appears I punched 15,000 W into the calculator. The signal improvement going from the resonant T to one with longer horizontal wires is quite minimal, about 0.1 dB. Dave WX7G __
/archives//html/Topband/2009-07/msg00112.html (8,689 bytes)

15. Re: Topband: Topband loaded dipole (score: 1)
Author: DAVID CUTHBERT <telegrapher9@gmail.com>
Date: Sun, 26 Jul 2009 12:11:15 -0600
110' loaded dipole: Here are NEC simulation results for a 110', 1.85 MHz dipole placed 50' above 'average' Sommerfield-Norton GND. The VSWR bandwidth is for the stated input impedance. For example, t
/archives//html/Topband/2009-07/msg00133.html (7,770 bytes)

16. Re: [TowerTalk] Topband: Antenna Modeling needed 160 vertical (score: 1)
Author: DAVID CUTHBERT <telegrapher9@gmail.com>
Date: Sat, 29 Aug 2009 18:04:57 -0600
Ed, here are some dimensions derived using EZNEC: Height 90', 4" diameter four #14 top hat wires 20' Base coil 5 uH (make coil 10 uH and tap it) Radiation resistance 22 ohms This article by K3LC will
/archives//html/Topband/2009-08/msg00104.html (9,240 bytes)

17. Re: [TowerTalk] Topband: Antenna Modeling needed 160 vertical (score: 1)
Author: DAVID CUTHBERT <telegrapher9@gmail.com>
Date: Sun, 30 Aug 2009 10:33:05 -0600
Ed, Let's compare the 90' top loaded vertical against a 90 foot vertical without top loading wires. Mechanically it might be nice to not have the top loading wires. In that case the radiation resista
/archives//html/Topband/2009-08/msg00107.html (11,851 bytes)

18. Re: Topband: Marconi vs. inverted L (score: 1)
Author: DAVID CUTHBERT <telegrapher9@gmail.com>
Date: Fri, 4 Sep 2009 19:41:34 -0600
Craig says: Phrasing it another way, what are the optimal take-off angles on 160 for working stations within a radius from 100 to 1000 miles? I'm located in Colorado, if that is any consideration. ..
/archives//html/Topband/2009-09/msg00017.html (7,455 bytes)

19. Re: Topband: Heartfelt EMI (score: 1)
Author: DAVID CUTHBERT <telegrapher9@gmail.com>
Date: Sat, 19 Sep 2009 10:36:51 -0600
Bob, using the "distance from hand carried antennas" and the frequency at which the data was taken one can infer the field strength (E and H field) that is acceptable to the pacemaker. At those frequ
/archives//html/Topband/2009-09/msg00080.html (8,126 bytes)

20. Re: Topband: What kind of mast is good for inverted L? (score: 1)
Author: DAVID CUTHBERT <telegrapher9@gmail.com>
Date: Tue, 22 Sep 2009 05:24:08 -0600
I have the 12 meter Spiderbeam mast. The top sections are very thin making the mast a useable 9 meters. The padded hose clamps they sell are needed to lock the sections in place. This mast will need
/archives//html/Topband/2009-09/msg00091.html (9,060 bytes)

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