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321. Re: Topband: T-200 vs. T-300 (score: 1): Author: "Rick Karlquist" <richard@karlquist.com>; Date: Thu, 15 Dec 2011 11:58:42 -0800; I'm trying to understand here what is magic about powdered iron. It is true you can't just use any random piece of ferrite. But if the T300A-2 were replaced with LOW PERMEABILITY ferrite having the s; /archives//html/Topband/2011-12/msg00392.html (9,259 bytes)
322. Re: Topband: 1820 BCB (score: 1): Author: "Rick Karlquist" <richard@karlquist.com>; Date: Wed, 21 Dec 2011 11:44:41 -0800; Intermods on even multiples of 10 kHz are simply a fact of life on 160 meters. Never operate exactly on one of these. In the recent Stew Perry, a station was absolutely zero beat at 1820. I was lucky; /archives//html/Topband/2011-12/msg00492.html (7,380 bytes)
323. Re: Topband: Xtal Filter +1 (score: 1): Author: "Rick Karlquist" <richard@karlquist.com>; Date: Wed, 4 Jan 2012 10:06:08 -0800; I don't see how noise overload of the receiver front end can be an issue. You can simply add front end attenuation such that the external noise just overcomes the receiver's internal noise. It would; /archives//html/Topband/2012-01/msg00056.html (9,900 bytes)
324. Re: Topband: Hi-Z Delay lines and new amps for four square (score: 1): Author: "Rick Karlquist" <richard@karlquist.com>; Date: Thu, 5 Jan 2012 12:26:07 -0800; Or you could make lumped element delay lines as follows: http://www.n6rk.com/Lumped_LC_Delay_Networks.gif I made an 4X2 array using these networks and it worked great. Rick N6RK _____________________; /archives//html/Topband/2012-01/msg00077.html (7,396 bytes)
325. Re: Topband: BC filter follow-up (score: 1): Author: "Rick Karlquist" <richard@karlquist.com>; Date: Fri, 6 Jan 2012 11:04:25 -0800; The Clifton filter is a Chebyshev, with only 14 dB attenuation at 1.7 MHz. What you really want is an elliptic function filter, of which there are several available. These can provide much more atten; /archives//html/Topband/2012-01/msg00101.html (7,447 bytes)
326. Re: Topband: BCI chase update (score: 1): Author: "Rick Karlquist" <richard@karlquist.com>; Date: Mon, 9 Jan 2012 15:09:14 -0800; On low bands, I routinely put a small (IE 10 pF) capacitor across the input of RF gain blocks to kill the bandwidth and prevent high frequency oscillations. With this in place, they should be fine wi; /archives//html/Topband/2012-01/msg00137.html (7,907 bytes)
327. Re: Topband: Where to place a preamp? Switching Beverages? (score: 1): Author: "Rick Karlquist" <richard@karlquist.com>; Date: Fri, 20 Jan 2012 14:12:30 -0800; This advice is spot on and something I have advocated for years. Transformer coupling is the only way to go for feedline isolation. Unfortunately, many hams want to use a common mode choke because th; /archives//html/Topband/2012-01/msg00213.html (10,245 bytes)
328. Re: Topband: What do you use as a "RUN" Antenna? (score: 1): Author: "Rick Karlquist" <richard@karlquist.com>; Date: Wed, 1 Feb 2012 12:00:25 -0800; I use the receive loop I wrote about in the National Contest Journal a few years ago. I rotate it to null out the noise du jour. You can vary the placement of the loop in your yard to best avoid the; /archives//html/Topband/2012-02/msg00008.html (8,396 bytes)
329. Re: Topband: 90 ft or 120 ft vert fer TB (score: 1): Author: "Rick Karlquist" <richard@karlquist.com>; Date: Thu, 9 Feb 2012 16:25:21 -0800; The advantage of top loading for the 90 footer will almost make up for the height advantage of the 120 footer. The structural degree of difficulty is much greater for 120 feet than 90 feet, so it wou; /archives//html/Topband/2012-02/msg00081.html (7,779 bytes)
330. Re: Topband: 160m dethroned? 600m the new top band? (score: 1): Author: "Richard (Rick) Karlquist" <richard@karlquist.com>; Date: Mon, 13 Feb 2012 07:10:00 -0800; The legal limit is defined in terms of EIRP, 1 to 5 watts. You only need a few percent efficiency if you have a reasonably powerful transmitter. Any decent 160 meter transmit antenna, with additional; /archives//html/Topband/2012-02/msg00192.html (8,907 bytes)
331. Re: Topband: Vertical vs yagi (score: 1): Author: "Rick Karlquist" <richard@karlquist.com>; Date: Tue, 14 Feb 2012 14:09:38 -0800; Your vertical array is of the "driven" (not parasitic) type. A 2 element driven array can, if properly tuned, have a F/B of 20, 30 or even 40 dB at some particular angle. A 2 element parasitic array; /archives//html/Topband/2012-02/msg00225.html (8,981 bytes)
332. Re: Topband: DXE Active Receive antenna question (score: 1): Author: "Rick Karlquist" <richard@karlquist.com>; Date: Sat, 18 Feb 2012 20:30:26 -0800; I found the same thing when I evaluated one of these years ago. It is just not a broadband design. The only thing you can do to mitigate the problem is to use taller verticals that simply bring in mo; /archives//html/Topband/2012-02/msg00293.html (7,651 bytes)
333. Re: Topband: DXE 8 Verticals (score: 1): Author: "Richard (Rick) Karlquist" <richard@karlquist.com>; Date: Mon, 20 Feb 2012 09:42:13 -0800; This is a confusing issue. Changing the links in the DXE amp definitely changes the gain. Whether it also also changes the signal to noise ratio depends on the relationship between external noise pic; /archives//html/Topband/2012-02/msg00296.html (8,308 bytes)
334. Re: Topband: EIRP Measurement (score: 1): Author: "Richard (Rick) Karlquist" <richard@karlquist.com>; Date: Tue, 21 Feb 2012 05:05:29 -0800; You can get an absolute calibration by the reciprocity method, using two identical antennas. An extension of this technique is the 3 antenna method which gets rid of the assumption that the antennas; /archives//html/Topband/2012-02/msg00302.html (7,718 bytes)
335. Re: Topband: EIRP Measurement (score: 1): Author: "Rick Karlquist" <richard@karlquist.com>; Date: Tue, 21 Feb 2012 12:31:49 -0800; Why is this method bulletproof? So you measure the RF current, which by the way is different below the loading coil than above the loading coil. How do you determine the radiation resistance of the a; /archives//html/Topband/2012-02/msg00311.html (8,720 bytes)
336. Re: Topband: EIRP Measurement (score: 1): Author: "Rick Karlquist" <richard@karlquist.com>; Date: Tue, 21 Feb 2012 17:58:21 -0800; The RF ammeter test merely measures the total radiated power. It does not account for the effective signal strength at some skywave angle. If it is true that the skywave is stronger than the ground w; /archives//html/Topband/2012-02/msg00316.html (7,930 bytes)
337. Re: Topband: Small loop Performance (score: 1): Author: "Richard (Rick) Karlquist" <richard@karlquist.com>; Date: Thu, 12 Apr 2012 18:19:04 -0700; stations? I've worked with a couple of loops based on N6RK's designs, and while they have deep nulls and work as expectred they also don't seem to produce any usable RF from DX stations. I can hear s; /archives//html/Topband/2012-04/msg00099.html (8,534 bytes)
338. Re: Topband: Small loop Performance (score: 1): Author: "Richard (Rick) Karlquist" <richard@karlquist.com>; Date: Sat, 14 Apr 2012 09:05:42 -0700; PC boards for the loop are still available. I have a 40x60 foot metal building. Surprisingly, it doesn't seem to interact much with the loop. OTOH, I have noticed interaction with wire antennas, powe; /archives//html/Topband/2012-04/msg00104.html (8,265 bytes)
339. Re: Topband: Using Video Baluns on 160. (score: 1): Author: "Rick Karlquist" <richard@karlquist.com>; Date: Mon, 7 May 2012 15:30:59 -0700; I did some design work on video baluns a few years ago. They consist of a large number of turns of twisted pair on an ungapped pot core. Old fashioned analog video is best sent with DC coupling. If t; /archives//html/Topband/2012-05/msg00083.html (8,525 bytes)
340. Topband: Using CAT5 in place of coax (was video baluns) (score: 1): Author: "Rick Karlquist" <richard@karlquist.com>; Date: Mon, 7 May 2012 17:07:51 -0700; I did some careful measurements of CAT5 cable a few years ago using a 4 port network analyzer (NOT a 2 port VNA with baluns). On my random sample, the characteristic impedance was within 5% of 100 oh; /archives//html/Topband/2012-05/msg00086.html (8,444 bytes)

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