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References: [ +subject:/^(?:^\s*(re|sv|fwd|fw)[\[\]\d]*[:>-]+\s*)*\[Amps\]\s+Looking\s+for\s+Alpha\s+87A\s+expertise\s*$/: 12 ]

Total 12 documents matching your query.

1. [Amps] Looking for Alpha 87A expertise (score: 1)
Author: "Jeff DePolo" <jd0@broadsci.com>
Date: Sun, 14 Mar 2021 11:27:31 -0400
A friend's 87A showed up on my bench. The symptom is fault code 1 (receive PIN back bias voltage not at minimum required level with key down and no RF drive) as soon as the key line is closed. This 8
/archives//html/Amps/2021-03/msg00002.html (9,230 bytes)

2. Re: [Amps] Looking for Alpha 87A expertise (score: 1)
Author: Steve Thompson <g8gsq72@gmail.com>
Date: Sun, 14 Mar 2021 19:16:19 +0000
2. Is a drop from 900V open-circuit to 730V typical when disconnecting/reconnecting the "R" bias lead at the HV board? I'm wondering if I have another leaky PIN diode or cap to ground that is loading
/archives//html/Amps/2021-03/msg00003.html (7,341 bytes)

3. Re: [Amps] Looking for Alpha 87A expertise (score: 1)
Author: Douglas L via Amps <amps@contesting.com>
Date: Sun, 14 Mar 2021 20:59:09 -0400
I have doubts about replacing those PIN diodes with 1N4007s. The 1N4007s dont switch quickly enough to substitute for a PIN. 73, Doug/WA1TUT _______________________________________________ Amps maili
/archives//html/Amps/2021-03/msg00006.html (8,518 bytes)

4. Re: [Amps] Looking for Alpha 87A expertise (score: 1)
Author: Jim <jimw7ry@gmail.com>
Date: Sun, 14 Mar 2021 21:16:15 -0500
Doug... How fast is a PIN diode?  How fast is a 1N4007 in an Alpha 87? If you have not measured their speed, how can you make that statement? Thanks 73 Jim W7RY 73, Doug/WA1TUT 2. Is a drop from 900V
/archives//html/Amps/2021-03/msg00007.html (9,809 bytes)

5. Re: [Amps] Looking for Alpha 87A expertise (score: 1)
Author: Benjamin Deovlet via Amps <amps@contesting.com>
Date: Mon, 15 Mar 2021 02:31:56 +0000 (UTC)
How fast is a PIN diode?  How fast is a 1N4007 in an Alpha 87? If you have not measured their speed, how can you make that statement? Thanks 73 Jim W7RY ______________________________________________
/archives//html/Amps/2021-03/msg00008.html (10,491 bytes)

6. Re: [Amps] Looking for Alpha 87A expertise (score: 1)
Author: Jim <jimw7ry@gmail.com>
Date: Sun, 14 Mar 2021 21:38:03 -0500
How much slower? Thanks 73 Jim W7RY On 3/14/2021 9:31 PM, Benjamin Deovlet wrote: From my design experience, the 1N400X diode is much much slower than PIN diodes. Ben, W6FDU In a message dated 3/14/2
/archives//html/Amps/2021-03/msg00009.html (11,420 bytes)

7. Re: [Amps] Looking for Alpha 87A expertise (score: 1)
Author: Ron W4BIN Youvan <ka4inm@gmail.com>
Date: Sun, 14 Mar 2021 22:52:58 -0400
Doug ... How fast is a PIN diode?  How fast is a 1N4007 in an Alpha 87? If you have not measured their speed, how can you make that statement? It is my understanding that the 1N4007 (only) IS a PIN
/archives//html/Amps/2021-03/msg00010.html (8,371 bytes)

8. Re: [Amps] Looking for Alpha 87A expertise (score: 1)
Author: Benjamin Deovlet via Amps <amps@contesting.com>
Date: Mon, 15 Mar 2021 02:57:16 +0000 (UTC)
  It is my understanding that the 1N4007 (only) IS a PIN diode and I have used them to replace PIN diodes in relay-less 2 meter transceivers up to 35. Watts and normal operation and power were restor
/archives//html/Amps/2021-03/msg00011.html (9,058 bytes)

9. Re: [Amps] Looking for Alpha 87A expertise (score: 1)
Author: Victor Rosenthal <k2vco.vic@gmail.com>
Date: Mon, 15 Mar 2021 12:49:24 +0200
There is a high-speed version of the 1N4007, the UF4007 whose recovery time is specified as 75 ns. That's pretty fast! See <https://www.vishay.com/docs/88755/uf4001.pdf> The regular 1N4007 is more li
/archives//html/Amps/2021-03/msg00012.html (9,854 bytes)

10. Re: [Amps] Looking for Alpha 87A expertise (score: 1)
Author: Jim <jimw7ry@gmail.com>
Date: Mon, 15 Mar 2021 23:57:51 -0500
Anything under 2ms  (2 milliseconds = 2000 microseconds, which is a whole bunch of nano seconds) is WAY MORE then enough for most transceivers. (Which was the point I was trying to make here). BUT if
/archives//html/Amps/2021-03/msg00013.html (11,072 bytes)

11. Re: [Amps] Looking for Alpha 87A expertise (score: 1)
Author: "Paul Christensen" <w9ac@arrl.net>
Date: Tue, 16 Mar 2021 07:32:43 -0400
A diode's forward bias transition time is one important parameter but when considering PIN diodes for use in the Alpha 87A, the diode's minority carrier lifetime may be an even more important parame
/archives//html/Amps/2021-03/msg00014.html (11,217 bytes)

12. Re: [Amps] Looking for Alpha 87A expertise (score: 1)
Author: MU 4CX250B <4cx250b@miamioh.edu>
Date: Tue, 16 Mar 2021 08:42:58 -0700
As an addendum to Pauls informative post, my own QSK circuit (QST June 2015, and http://www.w8zr.net/homebrew/) has a lock-on feature that keeps the amplifier locked on-line until RF from the exciter
/archives//html/Amps/2021-03/msg00017.html (11,609 bytes)

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