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Total 16 documents matching your query.

1. Topband: Buffaloed by a bias tee (score: 1): Author: Pete Smith N4ZR <n4zr@contesting.com>; Date: Wed, 22 Jan 2014 15:32:24 -0500; I'm still wrestling with the bias tee for my 1-of-8 remote beverage switch. If I use a cliplead to connect a 270-ohm dummy load, bypassing the relay, and connect an MFJ-259B to the receiver port on t; /archives//html/Topband/2014-01/msg00192.html (7,786 bytes)
2. Topband: Buffaloed by a bias tee (score: 1): Author: Pete Smith N4ZR <n4zr@contesting.com>; Date: Wed, 22 Jan 2014 17:20:15 -0500; Thanks to everyone for their suggestions - consensus seems to be that the homebrew chokes are not enough reactance at 1.8 MHz, so I'll get some store bought ones at 220 uH or more. I tried battery po; /archives//html/Topband/2014-01/msg00194.html (7,671 bytes)
3. Re: Topband: Buffaloed by a bias tee (score: 1): Author: "Tom W8JI" <w8ji@w8ji.com>; Date: Wed, 22 Jan 2014 17:34:22 -0500; The quickest way to blow up any test equipment, from a MFJ259 up to an HP network analyzer, is to use a bias T without input safeguards on the test gear. :-) I'm still wrestling with the bias tee for; /archives//html/Topband/2014-01/msg00195.html (10,202 bytes)
4. Re: Topband: Buffaloed by a bias tee (score: 1): Author: "Tom W8JI" <w8ji@w8ji.com>; Date: Wed, 22 Jan 2014 17:45:35 -0500; Thanks to everyone for their suggestions - consensus seems to be that the homebrew chokes are not enough reactance at 1.8 MHz, so I'll get some store bought ones at 220 uH or more. I tried battery po; /archives//html/Topband/2014-01/msg00196.html (8,697 bytes)
5. Re: Topband: Buffaloed by a bias tee (score: 1): Author: "Richard (Rick) Karlquist" <richard@karlquist.com>; Date: Wed, 22 Jan 2014 15:52:03 -0800; On 1/22/2014 12:32 PM, Pete Smith N4ZR wrote: . However, as soon as I connect a 12V regulated supply to the bias tee - one of the little radio shack variable wallwarts - the measured R drops to 5 ohm; /archives//html/Topband/2014-01/msg00197.html (8,170 bytes)
6. Re: Topband: Buffaloed by a bias tee (score: 1): Author: "Hardy Landskov" <n7rt@cox.net>; Date: Wed, 22 Jan 2014 19:15:40 -0700; This is really not rocket science--it's a simple matter of knowing what you are doing. Please contact me off line. After doing this for 40+ years I have had more than a modicum of sucess........ Hard; /archives//html/Topband/2014-01/msg00198.html (8,525 bytes)
7. Re: Topband: Buffaloed by a bias tee (score: 1): Author: Mike Waters <mikewate@gmail.com>; Date: Wed, 22 Jan 2014 21:56:31 -0600; 73, Mike www.w0btu.com _________________ Topband Reflector Archives - http://www.contesting.com/_topband; /archives//html/Topband/2014-01/msg00199.html (7,810 bytes)
8. Re: Topband: Buffaloed by a bias tee (score: 1): Author: "Richard (Rick) Karlquist" <richard@karlquist.com>; Date: Wed, 22 Jan 2014 22:11:55 -0800; 73, Mike www.w0btu.com Rick N6RK _________________ Topband Reflector Archives - http://www.contesting.com/_topband; /archives//html/Topband/2014-01/msg00201.html (8,248 bytes)
9. Re: Topband: Buffaloed by a bias tee (score: 1): Author: Pete Smith N4ZR <n4zr@contesting.com>; Date: Thu, 23 Jan 2014 11:07:56 -0500; Hi. Well, it does indeed seem to clinch it - when I power the tee but don't draw any current, the impedance measured by the MFJ does not change. So now to find some of the right sort of RFC. 73, Pete; /archives//html/Topband/2014-01/msg00204.html (9,783 bytes)
10. Re: Topband: Buffaloed by a bias tee (score: 1): Author: Mike Waters <mikewate@gmail.com>; Date: Thu, 23 Jan 2014 10:27:21 -0600; Here are the RFC part numbers, from http://www.ad5x.com/images/Articles/BiasT3amp.pdf "I finally settled on two J.W. Miller inductors that appeared acceptable. One was the 5250-RC 100 uHy inductor ra; /archives//html/Topband/2014-01/msg00205.html (8,536 bytes)
11. Re: Topband: Buffaloed by a bias tee (score: 1): Author: "Tom W8JI" <w8ji@w8ji.com>; Date: Thu, 23 Jan 2014 12:03:12 -0500; Hi Pete, You are going to have to trust me on this one. You really should **NOT** be measuring the input of the bias T with the MFJ 259 B analyzer with the configuration you have. You can damage the; /archives//html/Topband/2014-01/msg00206.html (13,125 bytes)
12. Re: Topband: Buffaloed by a bias tee (score: 1): Author: Pete Smith N4ZR <n4zr@contesting.com>; Date: Thu, 23 Jan 2014 13:45:29 -0500; Tom, I appreciate your concern. I have made these changes - I am now using a shunt choke (homebrew,, measuring 45 uH) and a smaller series capacitor.. Now all I have to do is to find a source of some; /archives//html/Topband/2014-01/msg00207.html (14,158 bytes)
13. Re: Topband: Buffaloed by a bias tee (score: 1): Author: "Richard (Rick) Karlquist" <richard@karlquist.com>; Date: Thu, 23 Jan 2014 11:15:56 -0800; capacitor.. Now all I have to do is to find a source of some appropriate chokes for the final tee, and my problems may be behind me. I was just looking at some Hammond chokes, no. 1532h - 100 uH, ra; /archives//html/Topband/2014-01/msg00208.html (9,843 bytes)
14. Re: Topband: Buffaloed by a bias tee (score: 1): Author: "Tom W8JI" <w8ji@w8ji.com>; Date: Thu, 23 Jan 2014 14:18:20 -0500; The Hammond is 400 mA and probably OK, I never used one. I use something like these 100 uH from Mouser Electronics: 542-73F104AF-RC or depending on current 542-5250-RC -- Original Message -- From: "P; /archives//html/Topband/2014-01/msg00210.html (15,649 bytes)
15. Re: Topband: Buffaloed by a bias tee (score: 1): Author: "ZR" <zr@jeremy.mv.com>; Date: Wed, 22 Jan 2014 16:23:29 -0500; That gives only a 509 Ohm reactance at 1800 Pete. Going to an oft suggested 100uH raises that to 1131 which is possibly sufficient. I use 220uH for a 2488 XL simply because I have a bunch from a hamf; /archives//html/Topband/2014-01/msg00215.html (11,086 bytes)
16. Re: Topband: Buffaloed by a bias tee (score: 1): Author: Herbert Schonbohm <herbert.schoenbohm@gmail.com>; Date: Thu, 23 Jan 2014 19:32:42 -0400; Mini Circuits makes a bias Tee box that has very low insertion loss down to 500Khz. It is their model*ZX85-12G-S*. and as Tom pointed out there is a change with current throughput and you can view th; /archives//html/Topband/2014-01/msg00219.html (16,857 bytes)

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