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References: [ +subject:/^(?:^\s*(re|sv|fwd|fw)[\[\]\d]*[:>-]+\s*)*\[Amps\]\s+50\s+Ohm\s+Loads\s*$/: 22 ]

Total 22 documents matching your query.

1. [Amps] 50 Ohm Loads (score: 1)
Author: "Bruce Lanning" <belanning@verizon.net>
Date: Sun, 11 Nov 2007 12:52:55 -0500
Hi, I note with interest what Larry had to say about filling load resisters. "Bring an Ohmmeter or get a guarantee from a mail order seller as the value can change considerably over time. I have a fe
/archives//html/Amps/2007-11/msg00150.html (6,607 bytes)

2. Re: [Amps] 50 Ohm Loads (score: 1)
Author: "Fuqua, Bill L" <wlfuqu00@uky.edu>
Date: Sun, 11 Nov 2007 13:45:37 -0500
Filing increases the value of the resistor. 73 Bill wa4lav Hi, I note with interest what Larry had to say about filling load resisters. "Bring an Ohmmeter or get a guarantee from a mail order seller
/archives//html/Amps/2007-11/msg00152.html (7,754 bytes)

3. Re: [Amps] 50 Ohm Loads (score: 1)
Author: "jeremy-ca" <km1h@jeremy.mv.com>
Date: Sun, 11 Nov 2007 14:27:36 -0500
That was Carl who wrote that. As you may know, the Carborundums are fragile being not much more than powdered carbon granules molded and held together by some bonding agent. I used a Dremel cut-off d
/archives//html/Amps/2007-11/msg00153.html (9,453 bytes)

4. Re: [Amps] 50 Ohm Loads (score: 1)
Author: "k7rdx" <k7rdx@charter.net>
Date: Sun, 11 Nov 2007 11:49:10 -0800
Has anyone checked with Palstar(800-773-7931) for load resistors? They build some really nice loads and may sell parts???Jim K7RDX.. -- Original Message -- From: "jeremy-ca" <km1h@jeremy.mv.com> To:
/archives//html/Amps/2007-11/msg00154.html (10,578 bytes)

5. Re: [Amps] 50 Ohm Loads (score: 1)
Author: Bill Fuqua <wlfuqu00@uky.edu>
Date: Sun, 11 Nov 2007 16:35:24 -0500
Filing resistors raise the resistance, you can't lower it that way. 73 Bill wa4lav _______________________________________________ Amps mailing list Amps@contesting.com http://lists.contesting.com/ma
/archives//html/Amps/2007-11/msg00155.html (8,028 bytes)

6. Re: [Amps] 50 Ohm Loads (score: 1)
Author: "Jim Brown" <jim@audiosystemsgroup.com>
Date: Sun, 11 Nov 2007 23:24:02 -0800
At a single frequency (or depending on the Q, a relatively narrow range). The laws of physics, as described by the classic resonant frequency curves, apply in full. Wire wound resistors as an RF dumm
/archives//html/Amps/2007-11/msg00158.html (7,572 bytes)

7. Re: [Amps] 50 Ohm Loads (score: 1)
Author: "jeremy-ca" <km1h@jeremy.mv.com>
Date: Mon, 12 Nov 2007 10:13:35 -0500
As one forum member pointed out 50KW BCB water cooled dummy loads use nichrome elements with a fixed cap to cancel the reactance. That is not a "narrow range". Measuring a true non inductive resistor
/archives//html/Amps/2007-11/msg00160.html (9,179 bytes)

8. Re: [Amps] 50 Ohm Loads (score: 1)
Author: "Jim Brown" <jim@audiosystemsgroup.com>
Date: Mon, 12 Nov 2007 08:48:50 -0800
It sure is a narrow range -- +/- 20 kHz! The laws of physics have not changed in my lifetime. 73, Jim _______________________________________________ Amps mailing list Amps@contesting.com http://list
/archives//html/Amps/2007-11/msg00163.html (7,689 bytes)

9. Re: [Amps] 50 Ohm Loads (score: 1)
Author: "jeremy-ca" <km1h@jeremy.mv.com>
Date: Mon, 12 Nov 2007 12:17:29 -0500
Youre missing the point; again. I said BCB, not one frequency. The loads covered up to 1500 KHz or so and above that the cap had to be changed. I see no reason why an inductive resistor cant be used
/archives//html/Amps/2007-11/msg00165.html (8,839 bytes)

10. Re: [Amps] 50 Ohm Loads (score: 1)
Author: "Jim Brown" <jim@audiosystemsgroup.com>
Date: Mon, 12 Nov 2007 09:35:01 -0800
I know you said that, but I don't believe it. 540-1700 kHz is a 3:1 range. In most RF systems, a dummy load needs to be pretty close to purely resistive. It is hard to believe that what you describe
/archives//html/Amps/2007-11/msg00167.html (8,355 bytes)

11. Re: [Amps] 50 Ohm Loads (score: 1)
Author: "jeremy-ca" <km1h@jeremy.mv.com>
Date: Mon, 12 Nov 2007 12:58:11 -0500
Since it was used succcessfuly by a Gates installation team in the 60's that statement is irrelevant. 540-1700 kHz is a 3:1 range. Without knowing the actual construction of the load or resistive ele
/archives//html/Amps/2007-11/msg00170.html (9,643 bytes)

12. Re: [Amps] 50 Ohm Loads (score: 1)
Author: "Jim Tonne" <tonne@comcast.net>
Date: Mon, 12 Nov 2007 13:29:50 -0500
On this business of resonating an inductive dummy load, I decided to put some numbers into the thing so we can sort the wheat from the chaff. First, I am sure that we are all in agreement that if the
/archives//html/Amps/2007-11/msg00172.html (9,008 bytes)

13. Re: [Amps] 50 Ohm Loads (score: 1)
Author: "Jim Brown" <jim@audiosystemsgroup.com>
Date: Mon, 12 Nov 2007 11:26:01 -0800
Yep. And the most practical way to do that is to measure it at RF. The test setup I published in my RFI tutorial to measure chokes would work. Most antenna analyzers would at least get us in the ball
/archives//html/Amps/2007-11/msg00174.html (8,156 bytes)

14. Re: [Amps] 50 Ohm Loads (score: 1)
Author: "jeremy-ca" <km1h@jeremy.mv.com>
Date: Mon, 12 Nov 2007 15:46:07 -0500
Jim, how about backing into Elsie with a .01 cap as that is what I believe Gates used in that load. With large diameter nichrome elements arranged in an array that minimized coupling I would have to
/archives//html/Amps/2007-11/msg00177.html (10,272 bytes)

15. Re: [Amps] 50 Ohm Loads (score: 1)
Author: "Jim Tonne" <tonne@comcast.net>
Date: Mon, 12 Nov 2007 16:32:29 -0500
Guys: If a .01 uF cap was used in series with a load to tune it to 1 MHz, then the load had an inductance of 2.533 uH. The return loss would be 20 dB or better over the range of 750 kHz to1320 kHz. I
/archives//html/Amps/2007-11/msg00179.html (9,081 bytes)

16. Re: [Amps] 50 Ohm Loads (score: 1)
Author: "jeremy-ca" <km1h@jeremy.mv.com>
Date: Mon, 12 Nov 2007 17:40:24 -0500
What about the other resistors? Immersed in oil they could handle some power. The Heath Cantenna used a 50W element. As mentioned earlier I was looking at single band applications at 1.8 and 3.8 MHz,
/archives//html/Amps/2007-11/msg00180.html (10,264 bytes)

17. Re: [Amps] 50 Ohm Loads (score: 1)
Author: "Jim Brown" <jim@audiosystemsgroup.com>
Date: Mon, 12 Nov 2007 15:21:32 -0800
How did you measure those values? At what frequency? What was the resistance at the frequency of the measurement? These are important questions, because that coil that we're calling a resistor has L,
/archives//html/Amps/2007-11/msg00182.html (8,283 bytes)

18. Re: [Amps] 50 Ohm Loads (score: 1)
Author: <d.cutter@ntlworld.com>
Date: Tue, 13 Nov 2007 8:31:51 +0000
So far no-one has mentioned non-inductive winding technique. I think Caddock use a method of winding in one direction, then half way along reverse the direction to complete the winding. David G3UNA -
/archives//html/Amps/2007-11/msg00186.html (7,926 bytes)

19. Re: [Amps] 50 Ohm Loads (score: 1)
Author: "Jim Brown" <jim@audiosystemsgroup.com>
Date: Tue, 13 Nov 2007 08:28:44 -0800
Don't know who Caddock is. First, we're talking about wire wound resistors here, not general coils. Second, if you believe a technique like this will work, I suggest you build one and measure it. 73,
/archives//html/Amps/2007-11/msg00187.html (8,351 bytes)

20. Re: [Amps] 50 Ohm Loads (score: 1)
Author: "Larry Benko, W0QE" <xxw0qe@comcast.net>
Date: Tue, 13 Nov 2007 09:38:01 -0700
Caddock resistors are great www.caddock.com and are very good at high frequencies. The 100W ones come in TO-247 transistor type packages and are a resistance film fired onto a flat ceramic substrate.
/archives//html/Amps/2007-11/msg00188.html (8,753 bytes)

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