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Total 37 documents matching your query.

1. [Amps] How to drive 6M 8877 with DownEast 50-28 ... IPA? (score: 1)
Author: "Tom Cathey" <k1jj@comcast.net>
Date: Mon, 29 Nov 2004 16:05:00 -0500
Hi All, I need to come up with a CLEAN 50W-70W IPA to drive my newly built 6 meter 8877. I have 20W available from a DownEast 50-28 transverter. An older N4NTA 6M kit using a single MRF-492 (10W to 1
/archives//html/Amps/2004-11/msg00457.html (8,083 bytes)

2. Re: [Amps] How to drive 6M 8877 with DownEast 50-28 ... IPA? (score: 1)
Author: "Tom Cathey" <k1jj@comcast.net>
Date: Mon, 29 Nov 2004 16:17:37 -0500
BTW, Used as an IPA: Is it possible to clean up the N4LTA 6M MRF-492 brick by idling it at several amps (instead of 100ma) - closer to class A1 and adding some negative feedback via an emitter resist
/archives//html/Amps/2004-11/msg00458.html (7,171 bytes)

3. Re: [Amps] How to drive 6M 8877 with DownEast 50-28 ... IPA? (score: 1)
Author: "Tom Cathey" <k1jj@comcast.net>
Date: Tue, 30 Nov 2004 14:06:37 -0500
Hi Marv, Your idea about using a 4CX350J IPA is interesting. I suppose it would have to be VERY physically close to the 8877 or the RF negative feedback will have phase shift problems. ie, It will no
/archives//html/Amps/2004-11/msg00462.html (9,452 bytes)

4. Re: [Amps] TL-922A - Loud Pop, Blown Fuses (score: 1)
Author: "Tom Cathey" <k1jj@comcast.net>
Date: Sat, 4 Dec 2004 15:15:44 -0500
Hi Clay, Not sure if this happens as soon as you throw the HV switch or not... but: Start with a "conquer and divide" technique. With plug unplugged and unit off, with an ohmmeter that can read diode
/archives//html/Amps/2004-12/msg00076.html (9,285 bytes)

5. Re: [Amps] TL-922A - Loud Pop, Blown Fuses (score: 1)
Author: "Tom Cathey" <k1jj@comcast.net>
Date: Sun, 5 Dec 2004 17:46:31 -0500
Hi Clay, That's good - you've made some progress and eliminated 1/2 of the rig. I take it you have no good 3-500Z spares to try. If not, I wouldn't worry about blowing anything up by popping fuses. P
/archives//html/Amps/2004-12/msg00089.html (13,978 bytes)

6. Re: [Amps] TL-922 and overdriving (score: 1)
Author: "Tom Cathey" <k1jj@comcast.net>
Date: Thu, 9 Dec 2004 12:58:06 -0500
Oliver, You may know the following info already, but just in case... just setting the drive power at an arbitrary level is not a good idea for several reasons... Lets say the final tubes are getting
/archives//html/Amps/2004-12/msg00152.html (9,416 bytes)

7. [Amps] Designing the Cleanest Linear with RF Negative Feedback (score: 1)
Author: "Tom Cathey" <K1JJ@comcast.net>
Date: Wed, 14 Dec 2005 12:49:14 -0500
Hi All, I'm planning to build up a 75M monoband amplifier that has at least -45db to -50db 3rd order IMD using heavy RF negative feedback. 10MW in, 1500W out. I wanted to get opinions here what other
/archives//html/Amps/2005-12/msg00162.html (8,286 bytes)

8. Re: [Amps] Designing the Cleanest Linear with RF Negative Feedback (score: 1)
Author: "Tom Cathey" <K1JJ@comcast.net>
Date: Wed, 14 Dec 2005 17:27:30 -0500
Thanks for all the replies! cheezz... I got close to 15 private ones and they're still coming in - really appreciate the ideas, guys. Please excuse me if I don't answer them all... K5GZ [good whiskey
/archives//html/Amps/2005-12/msg00171.html (10,182 bytes)

9. Re: [Amps] Designing the Cleanest Linear with RF Negative Feedback (score: 1)
Author: "Tom Cathey" <K1JJ@comcast.net>
Date: Wed, 14 Dec 2005 17:45:14 -0500
Yes, Gerald, I thought about the DC bias variation too... the fact it would be swinging under ssb modulation... and thought that was not a good thing unless the tube was run in class A. This is class
/archives//html/Amps/2005-12/msg00173.html (12,261 bytes)

10. Re: [Amps] Designing the Cleanest Linear with RF Negative Feedback (score: 1)
Author: "Tom Cathey" <K1JJ@comcast.net>
Date: Thu, 15 Dec 2005 00:09:34 -0500
Correction: It was pointed out to me that the cathode resistor for negative feedback is to be used only for a grid driven [grounded cathode] amplifier to generate degenerative [negative] feedback. In
/archives//html/Amps/2005-12/msg00175.html (8,552 bytes)

11. Re: [Amps] Designing the Cleanest Linear with RF Negative Feedback (score: 1)
Author: "Tom Cathey" <K1JJ@comcast.net>
Date: Thu, 15 Dec 2005 12:44:13 -0500
Thanks for the replies. Let's address a few comments. I'm trying to get the right direction to follow, then do some serious, focused study in the right areas. One comment: Why bother to get better li
/archives//html/Amps/2005-12/msg00186.html (12,124 bytes)

12. Re: [Amps] Designing the Cleanest Linear with RF Negative Feedback (score: 1)
Author: "Tom Cathey" <K1JJ@comcast.net>
Date: Thu, 15 Dec 2005 14:20:28 -0500
I like BOTH suggestions, Gary! Having the input link phase reversable opens the door for GG driving GG experiments. For the GG input drive NFB resistor, what value would you try for an 8877 input? It
/archives//html/Amps/2005-12/msg00189.html (10,965 bytes)

13. Re: [Amps] Designing the Cleanest Linear with RF Negative Feedback (score: 1)
Author: "Tom Cathey" <K1JJ@comcast.net>
Date: Thu, 15 Dec 2005 19:31:47 -0500
Hi Marv! Now THAT'S the kind of info I've been looking for, OM. OK on using the 'J' tube versions and the TRW class A chips. I imagine the J's are harder to find used. I went to a site that has a CA5
/archives//html/Amps/2005-12/msg00194.html (10,853 bytes)

14. Re: [Amps] Designing the Cleanest Linear with RF Negative Feedback (score: 1)
Author: "Tom Cathey" <K1JJ@comcast.net>
Date: Fri, 16 Dec 2005 16:25:17 -0500
That's more valuable info, Marv - Tnx again! A few follow up questions: If I tap off the FT-1000D 10mW low level point, can I run a long ~ 20' coax cable to the amplifier CA2XX module's input, or wil
/archives//html/Amps/2005-12/msg00211.html (11,497 bytes)

15. Re: [Amps] Designing the Cleanest Linear with RF Negative Feedback (score: 1)
Author: "Tom Cathey" <K1JJ@comcast.net>
Date: Fri, 16 Dec 2005 20:25:50 -0500
Hi Gary, Tnx for the IMD measurement info. Sounds easy enough. Actually I've been doing a similar thing, but using a recorded voice to play thru the rig and measure the bandwidth and levels. I will m
/archives//html/Amps/2005-12/msg00214.html (16,191 bytes)

16. Re: [Amps] Designing the Cleanest Linear with RF Negative Feedback (score: 1)
Author: "Tom Cathey" <K1JJ@comcast.net>
Date: Sat, 17 Dec 2005 11:45:35 -0500
Marv, Just as a note on your Hughes sample amplifier URL below.... I see no negative DC bias on either the 4CX-250 nor the 4X10. Strange that it's not there. Bias is OK on the 6146. Would appropriate
/archives//html/Amps/2005-12/msg00226.html (9,702 bytes)

17. Re: [Amps] Designing the Cleanest Linear with RF Negative Feedback (score: 1)
Author: "Tom Cathey" <K1JJ@comcast.net>
Date: Sat, 17 Dec 2005 14:46:39 -0500
Thank you Marv. You da man! That answers a lot. I'll ask you just a few more, please, and then let you be... :-) I've got a few of 4-400A's, sockets and chimneys here. I was hoping to substitute one
/archives//html/Amps/2005-12/msg00232.html (12,503 bytes)

18. Re: [Amps] Designing the Cleanest Linear with RF Negative Feedback (score: 1)
Author: "Tom Cathey" <K1JJ@comcast.net>
Date: Sun, 18 Dec 2005 13:56:32 -0500
Hi Marv, Well, you've given me a lot to think about. I'll look for cleaner drivers than the 6146 and 4-400A. You make a good point about not giving up IMD in that lower level area, if there is an eas
/archives//html/Amps/2005-12/msg00248.html (12,369 bytes)

19. Re: [Amps] Designing the Cleanest Linear with RF Negative Feedback (score: 1)
Author: "Tom Cathey" <K1JJ@comcast.net>
Date: Sun, 18 Dec 2005 15:31:49 -0500
Aw, you guys are brutal! Here's what I REALLY look like: http://home.comcast.net/~k1jj/wsb/media/254120/site1050.jpg Marv, OK on the FT-1000D feed forward info. Interesting alternative. Though, chang
/archives//html/Amps/2005-12/msg00253.html (9,870 bytes)

20. Re: [Amps] Designing the Cleanest Linear with RF Negative Feedback (score: 1)
Author: "Tom Cathey" <K1JJ@comcast.net>
Date: Sun, 18 Dec 2005 18:22:52 -0500
Hi Peter, Yes, that's an interesting tube line up. I'm kinda leaning that way. That's a great way to provide voltage for both the final's screen and driver's plates. One regulated supply - I like it.
/archives//html/Amps/2005-12/msg00256.html (10,631 bytes)


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