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Total 9 documents matching your query.

1. [Amps] QRO HF2000 tank coil Q question (score: 1): Author: John Keating <john.keating@outlook.com>; Date: Mon, 22 Mar 2021 16:22:43 +0000; Wondering if anyone can provide the specs on the low band tank coil for a QRO HF2000. It appears to be a stack of two red-mix T225A-2 iron powder toroids, with a total of 25 turns, and taps for 40M a; /archives//html/Amps/2021-03/msg00025.html (6,675 bytes)
2. Re: [Amps] QRO HF2000 tank coil Q question (score: 1): Author: "Peter Voelpel" <dj7ww@t-online.de>; Date: Mon, 22 Mar 2021 18:51:44 +0100; I used stacks of T225-2 for a mobile antenna loading coil on 40m. Measured Q was around 400. Toroid coils with taps, which no good idea anyway, will have much lower Q. As part of a pi network for 160; /archives//html/Amps/2021-03/msg00026.html (7,669 bytes)
3. Re: [Amps] QRO HF2000 tank coil Q question (score: 1): Author: John Keating <john.keating@outlook.com>; Date: Mon, 22 Mar 2021 18:05:34 +0000; Thanks Peter. I calculate a Q of 7 to 8 for the stock design mentioned in the previous email. There are still a fair number of these amps in use, I wondered if others had similar experience. I consid; /archives//html/Amps/2021-03/msg00027.html (9,349 bytes)
4. Re: [Amps] QRO HF2000 tank coil Q question (score: 1): Author: "Peter Voelpel" <dj7ww@t-online.de>; Date: Mon, 22 Mar 2021 19:47:06 +0100; Hi John, With the Q of 7 to 8 you probably mean the pi network Q. That is not the Q of the particular coil but that of the circuit, calculated by tube Ra/Xc of anode capacitor. Higher Q will produce; /archives//html/Amps/2021-03/msg00028.html (9,268 bytes)
5. Re: [Amps] QRO HF2000 tank coil Q question (score: 1): Author: Jim <jimw7ry@gmail.com>; Date: Mon, 22 Mar 2021 18:37:26 -0500; I recommend an open coil type. Especially on 40 and 80. I tried torids in my 8877 amp and had the 160 meter unit overheat and start to smoke when on 10 meters! Yes, the 160 meter Pi torid over heated; /archives//html/Amps/2021-03/msg00029.html (8,043 bytes)
6. Re: [Amps] QRO HF2000 tank coil Q question (score: 1): Author: gudguyham via Amps <amps@contesting.com>; Date: Tue, 23 Mar 2021 01:24:38 +0000 (UTC); Have you guys taken into consideration that the tank circuit in these amps only transform down to 200 ohms, not 50 ohms from the plate impedance? After the tank circuit it passes through a 4 to 1 ba; /archives//html/Amps/2021-03/msg00030.html (10,484 bytes)
7. Re: [Amps] QRO HF2000 tank coil Q question (score: 1): Author: John Keating <john.keating@outlook.com>; Date: Tue, 23 Mar 2021 01:28:30 +0000; yes I took that into consideration for the calculations. Have you guys taken into consideration that the tank circuit in these amps only transform down to 200 ohms, not 50 ohms from the plate impedan; /archives//html/Amps/2021-03/msg00031.html (11,272 bytes)
8. [Amps] QRO HF2000 tank coil Q question (score: 1): Author: "Jim Thomson" <jim.thom@telus.net>; Date: Tue, 23 Mar 2021 11:07:36 -0700; <I recommend an open coil type. Especially on 40 and 80. I tried toroids <in my 8877 amp and had the 160 meter unit overheat and start to smoke <when on 10 meters! <Yes, the 160 meter Pi toroid over; /archives//html/Amps/2021-03/msg00032.html (9,032 bytes)
9. Re: [Amps] QRO HF2000 tank coil Q question (score: 1): Author: MU 4CX250B <4cx250b@miamioh.edu>; Date: Tue, 23 Mar 2021 16:45:56 -0400; Jim raises an issue which has troubled me lately, and that is whether the added expense and headaches required to build a bandswitched pi-L tank circuit is justified by the modest gain in harmonic at; /archives//html/Amps/2021-03/msg00033.html (9,067 bytes)

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