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Components and Circuits For discussions about component types, alternatives and availability, circuit configurations and modifications etc. Discussions here should be of a general nature and not about specific sets. |
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7th Jun 2018, 5:40 pm | #21 |
No Longer a Member
Join Date: Oct 2016
Location: Maroochydore, Queensland, Australia.
Posts: 2,679
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Re: Amidon and Micrometals toroids.. other brands ?
It would work, but anything in the region of 10uH to 50uH would probably be plenty too. One trick to avoid having to have another core or toroid is simply to thread a few ferrite beads over the tinned copper wire that leads to the center tap and the bypass capacitor.
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7th Jun 2018, 6:29 pm | #22 |
Nonode
Join Date: Nov 2015
Location: Welwyn Garden City, Hertfordshire, UK.
Posts: 2,013
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Re: Amidon and Micrometals toroids.. other brands ?
I have enjoyed this thread very much.
Just one thing - the CB transistors specified in the Chris Honey design now hard to obtain. You still find them listed but in my experience, if you buy, what you get are fakes. There are Semelab parts D1001,D1002 etc - same story. Some I received had been re-cycled! You could see milling marks on the tabs where old solder had been removed. It's a mine field. Also forget to mention in connection with original topic.. What do we know about Palomar Engineers? They have also been a source of Iron-dust and Ferrite cores I think. Is it just an alternative name? Last edited by Jon_G4MDC; 7th Jun 2018 at 6:35 pm. |
7th Jun 2018, 10:27 pm | #23 | |
No Longer a Member
Join Date: Oct 2016
Location: Maroochydore, Queensland, Australia.
Posts: 2,679
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Re: Amidon and Micrometals toroids.. other brands ?
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One other point, if you are using different transistors to the ones I used, the bias resistor may have to be altered so the voltage drop across the 1N4004 is about right for the particular transistors , and possibly a low value resistor might need to be placed in series with the 1N4004. In any case, when your amplifier is finished, you will need to load it into an appropriate non inductive 50R dummy load and feed it with a generator and examine the output on the scope to make sure all is well. |
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7th Jun 2018, 11:08 pm | #24 | ||
Retired Dormant Member
Join Date: Feb 2013
Location: Québec City, Québec, Canada
Posts: 42
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Re: Amidon and Micrometals toroids.. other brands ?
[QUOTE=Argus25;1050002]
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I don't have any and they list around $30.00 each on eBay!! Way too expensive for my project.. BUT I checked in my power transistor bin and found some MJE15028G power NPN's rated at 30Mhz min, 50W, Vce 120v and Ic continuous 8amp. https://www.onsemi.com/pub/Collateral/MJE15028-D.PDF I know this is not the 'normal' transistor to pick up for such a project but I should give a try since it will run at a low 1,400khz freq. carrier. I tested the hfe and it stays around 100 up to Ic = 2.5amp. The hfe starts to drop a little passed 2.5amp. Your feedbacks are greatly appreciated ! |
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