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1. [Amps] amp update and question (score: 1): Author: Dan Sawyer <dansawyer@earthlink.net>; Date: Sun, 16 Aug 2009 19:17:03 -0700; The progress to 'adapt' an ENI amplifier to ham use is continuing, although suffering some from other summer activities. The current status is: 1. biasing is working, based on a simple resistor diode; /archives//html/Amps/2009-08/msg00339.html (7,322 bytes)
2. Re: [Amps] RF power transistor curve trace question (score: 1): Author: Dan Sawyer <dansawyer@earthlink.net>; Date: Mon, 15 Jun 2009 19:46:45 -0700; Yes, a family of collector voltage and collector current curves. The step is the change in the base current. The tracer is not able to drive that much current, however it is able to drive one amp. At; /archives//html/Amps/2009-06/msg00074.html (10,533 bytes)
3. Re: [Amps] RF power transistor curve trace question (score: 1): Author: Dan Sawyer <dansawyer@earthlink.net>; Date: Sun, 14 Jun 2009 19:02:38 -0700; Manfred, as always thank you for your response. Below are the answers: 1. the trace is a collector voltage horizontal and collector current vertical. The tracer is a Tek 577, the collector sweep is s; /archives//html/Amps/2009-06/msg00071.html (9,618 bytes)
4. [Amps] RF power transistor curve trace question (score: 1): Author: Dan Sawyer <dansawyer@earthlink.net>; Date: Sat, 13 Jun 2009 20:07:09 -0700; All, this is a continuing question in the quest to understand and modify an ENI base bipolar power amp. I speculated the power transistors were SD1728's however I am not so sure. I have one SD1728 fr; /archives//html/Amps/2009-06/msg00064.html (7,366 bytes)
5. [Amps] bipolar input and output impedance (score: 1): Author: Dan Sawyer <dansawyer@earthlink.net>; Date: Thu, 04 Jun 2009 07:35:21 -0700; What are the bipolar HF power transistor specs that influence or determine the input and output impedance? I have an ENI circuit using TH430 transistors with 4:1 input and output transformers, the EB; /archives//html/Amps/2009-06/msg00014.html (7,176 bytes)
6. [Amps] Motorola app note eb-63 question (score: 1): Author: Dan Sawyer <dansawyer@earthlink.net>; Date: Thu, 04 Jun 2009 06:51:00 -0700; I am trying to convert an ENI TH430 based RF power amp to 'mimic' the EB 63 circuit. Can someone provide a starting point for the purpose and selection of C8 and C9 between collector and emitter? Wha; /archives//html/Amps/2009-06/msg00013.html (6,778 bytes)
7. Re: [Amps] designing and testing RF Bipolar Power bias circuit (score: 1): Author: Dan Sawyer <dansawyer@earthlink.net>; Date: Sat, 30 May 2009 12:02:11 -0700; Manfred, Thank you again for your input. The insight into the bias circuit was very helpful. I replaced the curve tracer with a variable power supply; that improved the response considerably. The pla; /archives//html/Amps/2009-05/msg00270.html (11,116 bytes)
8. [Amps] designing and testing RF Bipolar Power bias circuit (score: 1): Author: Dan Sawyer <dansawyer@earthlink.net>; Date: Wed, 27 May 2009 19:29:47 -0700; All, I am converting a TH430 based Class C amplifier to Class AB. The basic circuit is a traditional single stage layout with input and output binocular transformers. Things are proceeding, however t; /archives//html/Amps/2009-05/msg00230.html (7,489 bytes)
9. [Amps] purpose of 3 ohm resisters between base and emitter? (score: 1): Author: Dan Sawyer <dansawyer@earthlink.net>; Date: Tue, 28 Apr 2009 07:04:31 -0700; All, I have an ENI power amp with what look like SD 1726 transistors in a class C configuration. The circuit is pretty standard, however there are 3 ohm resistors between the base and the emitters. C; /archives//html/Amps/2009-04/msg00391.html (6,973 bytes)
10. [Amps] HF power amp input impedance (score: 1): Author: Dan Sawyer <dansawyer@earthlink.net>; Date: Sun, 05 Apr 2009 20:53:37 -0700; I have an older solid state amp based on a pair of MRF 454s. The amp is missing three common design features found in most similar HF power amps, a bias circuit for the base, negative feedback, and a; /archives//html/Amps/2009-04/msg00066.html (7,405 bytes)
11. [Amps] bifilar wound toroid core frequency response (score: 1): Author: Dan Sawyer <dansawyer@earthlink.net>; Date: Mon, 30 Mar 2009 20:35:58 -0700; Hello, this is a question relating to a bifilar winding around various torroid cores. The winding was made from two pieces of #26 enamel wire about 6 inches long and wound at 3 to 4 turns per inch. T; /archives//html/Amps/2009-03/msg00547.html (7,554 bytes)
12. Re: [Amps] 'red' cores versus 43 cores (score: 1): Author: Dan Sawyer <dansawyer@earthlink.net>; Date: Sat, 28 Mar 2009 19:27:02 -0700; Thanks to all of you for the replies. The first interest is to build and test a 300 watt input and output transformer pair. The reason I chose #43 to discuss was it was mentioned in at least one of t; /archives//html/Amps/2009-03/msg00522.html (7,951 bytes)
13. [Amps] 'red' cores versus 43 cores (score: 1): Author: Dan Sawyer <dansawyer@earthlink.net>; Date: Sat, 28 Mar 2009 17:00:41 -0700; Is there a straightforward practical or operational description of the difference between 'red' cores and 43 material. The magnetic differences are large. However, the 'red' cores are used in low pow; /archives//html/Amps/2009-03/msg00518.html (7,651 bytes)
14. [Amps] measuring bandpass of a power amp with an NA (score: 1): Author: Dan Sawyer <dansawyer@earthlink.net>; Date: Sun, 08 Mar 2009 13:05:20 -0700; I have a couple solid state RF power amps to test. One question is: What is their bandpass? I connected a network analyser drive to the output and then took the NA input of the collectors. Accounting; /archives//html/Amps/2009-03/msg00243.html (7,111 bytes)
15. [Amps] testing RF power MOSFET devices (score: 1): Author: Dan Sawyer <dansawyer@earthlink.net>; Date: Sun, 22 Feb 2009 19:59:28 -0800; This is a general question regarding 'testing' RF power MOSFETs 1. There appears to be a difference between the MRF150 and the ST equivalent based on the 'simple' test of placing the negative lead of; /archives//html/Amps/2009-02/msg00654.html (7,547 bytes)
16. [Amps] ST 681033a ? (score: 1): Author: Dan Sawyer <dansawyer@earthlink.net>; Date: Fri, 13 Feb 2009 18:33:38 -0800; Does anyone know the common part number for an ST 681033A. If not what part is it closest to? Thanks, Dan _______________________________________________ Amps mailing list Amps@contesting.com http://; /archives//html/Amps/2009-02/msg00432.html (6,340 bytes)
17. [Amps] ST 681033A ? (score: 1): Author: Dan Sawyer <dansawyer@earthlink.net>; Date: Tue, 08 Jul 2008 19:11:16 -0700; Does anyone know what an ST 681033A is a match for? I suspect is is a match for an MRF150. Thanks, Dan _______________________________________________ Amps mailing list Amps@contesting.com http://lis; /archives//html/Amps/2008-07/msg00076.html (6,369 bytes)
18. [Amps] 10 meter amp frequency limitation (score: 1): Author: Dan Sawyer <dansawyer@earthlink.net>; Date: Sun, 02 Mar 2008 19:45:43 -0800; All, I am trying to figure where in a 10 meter power amp with MRF454s the low band frequency limit is? This is a relatively simple amp. The circuit looks identical to the classic Motorola Granberg EB; /archives//html/Amps/2008-03/msg00027.html (6,768 bytes)
19. Re: [Amps] how to wind an HF broadband 10:1 transformer (score: 1): Author: Dan Sawyer <dansawyer@earthlink.net>; Date: Sun, 02 Mar 2008 19:06:11 -0800; Peter, Are you saying number 2, red, and number 6, yellow, material cores are not suitable for low power broadband transformers? Or is this a power and heating issue that is not relevant at low power; /archives//html/Amps/2008-03/msg00024.html (9,802 bytes)
20. Re: [Amps] how to wind an HF broadband 10:1 transformer (score: 1): Author: Dan Sawyer <dansawyer@earthlink.net>; Date: Fri, 29 Feb 2008 20:19:47 -0800; Manfred, How many turns were on the 50 ohm winding? Thanks, Dan _______________________________________________ Amps mailing list Amps@contesting.com http://lists.contesting.com/mailman/listinfo/amps; /archives//html/Amps/2008-03/msg00019.html (15,554 bytes)

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