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Total 544 documents matching your query.

1. Re: [Amps] 'heat spreader' sizing ?? (score: 1)
Author: "K8RI (Roger)" <K8RI@rogerhalstead.com>
Date: Tue, 08 Feb 2011 00:40:39 -0500
To me they look kinda impractical for linear techniques and particularly at HF. A 1200 watt transistor to get an average of 200 out? 73 Roger (K8RI) _______________________________________________ Am
/archives//html/Amps/2011-02/msg00054.html (8,475 bytes)

2. [Amps] What is a 4CX3000A...+ EI ? (score: 1)
Author: K8RI <k8ri@rogerhalstead.com>
Date: Fri, 14 Oct 2011 14:58:24 -0400
I know what a 4CX3000A1 and A7 are, but what does the +EI stand for? Is that a one or the letter "I"? I've never seen the designation given like that before. 73 Roger (K8RI) _________________________
/archives//html/Amps/2011-10/msg00040.html (6,878 bytes)

3. Re: [Amps] PRO III and ALpha 76 (score: 1)
Author: "Roger (K8RI)" <k8ri@rogerhalstead.com>
Date: Sun, 11 Dec 2011 01:59:17 -0500
I'm not familiar with all of your set up, but I have found that my 756 Pro (not a III) will not key the 76A unaided. I welded the relay contacts together the first time I used it. OTOH it keyed the H
/archives//html/Amps/2011-12/msg00092.html (7,768 bytes)

4. Re: [Amps] Warm up and on time question... (score: 1)
Author: "Roger (K8RI)" <k8ri@rogerhalstead.com>
Date: Sat, 17 Dec 2011 03:46:45 -0500
Just use a Triac and let it ramp up the voltage over a few seconds...say 5 or 10. After the ramp up, switch out the Triac with a relay as they tend to be a bit noisy. Mostly it's the diac keying that
/archives//html/Amps/2011-12/msg00130.html (10,757 bytes)

5. Re: [Amps] Warm up and on time question... (score: 1)
Author: "Roger (K8RI)" <k8ri@rogerhalstead.com>
Date: Sat, 17 Dec 2011 04:45:17 -0500
The data sheets I have do not list any warm up times. IOW, throw the switch and go. It does state that Inrush current should be limited to two times normal current during turn on to limit thermal str
/archives//html/Amps/2011-12/msg00131.html (10,568 bytes)

6. Re: [Amps] Is after-powerdown cooling desirable? (score: 1)
Author: "Roger (K8RI)" <k8ri@rogerhalstead.com>
Date: Tue, 20 Dec 2011 00:21:34 -0500
Not all tubes do this and my experience is limited to just a few. The filament and cathode are probably the most massive structures in there other than the anode which has plenty of cooling. If I kil
/archives//html/Amps/2011-12/msg00150.html (10,490 bytes)

7. Re: [Amps] Fwd: Linear Amplifier Tuning---PROPERLY! (score: 1)
Author: "Roger (K8RI)" <k8ri@rogerhalstead.com>
Date: Wed, 28 Dec 2011 01:35:21 -0500
If it's really as bad as they measured (which I assume it is) then I'd also assume that there are going to be a lot of disappointed users as well. Course if they only use them on FM will any one noti
/archives//html/Amps/2011-12/msg00243.html (11,368 bytes)

8. Re: [Amps] Fwd: Linear Amplifier Tuning---PROPERLY! (score: 1)
Author: "Roger (K8RI)" <k8ri@rogerhalstead.com>
Date: Wed, 28 Dec 2011 18:48:54 -0500
Let me take a shot at this: I'm sure some one else can do this more clearly than I but... First, lets separate the lower stages from the driver and final. Lets say your transceiver has an audio pass
/archives//html/Amps/2011-12/msg00252.html (11,059 bytes)

9. Re: [Amps] Fwd: Linear Amplifier Tuning---PROPERLY! (score: 1)
Author: "Roger (K8RI)" <k8ri@rogerhalstead.com>
Date: Wed, 28 Dec 2011 18:03:36 -0500
Just think what the bands would sound like if we were still using SSB rigs from the 60's<:-)) Even the Collins and Hallicrafters were not all that great. There were exceptions, but not many. Of cours
/archives//html/Amps/2011-12/msg00253.html (12,732 bytes)

10. Re: [Amps] Fwd: Linear Amplifier Tuning---PROPERLY! (score: 1)
Author: "Roger (K8RI)" <k8ri@rogerhalstead.com>
Date: Thu, 29 Dec 2011 02:01:46 -0500
Like trying to get a KW out of a single 3-500? or the ham's voice getting louder as he/she tries to get just another watt out to make it through the pileup. Another reason for getting an amp with a f
/archives//html/Amps/2011-12/msg00264.html (11,524 bytes)

11. Re: [Amps] IMD (score: 1)
Author: "Roger (K8RI)" <k8ri@rogerhalstead.com>
Date: Thu, 29 Dec 2011 18:12:15 -0500
Hi Dick, First I'd suggest reading the thread on Linear Amplifier Tuning ...Properly and The folly of using a TX tube beyond its ratings over on Ham Amps. It gets a bit colorful at times but there ar
/archives//html/Amps/2011-12/msg00275.html (10,528 bytes)

12. Re: [Amps] 4CX1000A (score: 1)
Author: "Roger (K8RI)" <k8ri@rogerhalstead.com>
Date: Fri, 27 Jan 2012 16:23:17 -0500
Are you familiar with Tetrode tuning? At what level of screen current do you start getting secondary emission? I've not heard of any problems with GE constructed 4CX1000A's. GE has built a lot of hig
/archives//html/Amps/2012-01/msg00216.html (10,013 bytes)

13. Re: [Amps] 4CX1000A (score: 1)
Author: "Roger (K8RI)" <k8ri@rogerhalstead.com>
Date: Fri, 27 Jan 2012 16:32:22 -0500
I forgot to mention that most of these tubes run reverse screen current with low drive and power levels. Mine (4CX1500B/FU728F) only goes to positive screen current near the US legal limit output. At
/archives//html/Amps/2012-01/msg00217.html (9,695 bytes)

14. Re: [Amps] 4CX1000A (score: 1)
Author: "Roger (K8RI)" <k8ri@rogerhalstead.com>
Date: Fri, 27 Jan 2012 17:10:56 -0500
This not only makes the regulated supply much more simple as the supply always sees a positive load. The value of the resistor should be of such that the supply always sees a normal load that never g
/archives//html/Amps/2012-01/msg00219.html (9,898 bytes)

15. Re: [Amps] 4CX1000A (score: 1)
Author: "Roger (K8RI)" <k8ri@rogerhalstead.com>
Date: Sat, 28 Jan 2012 16:12:14 -0500
Typically all I've used ran well at reduced power levels even with reversed screen current, but I've never seen a need for running an amp at less than half to three quarters power. The idea just neve
/archives//html/Amps/2012-01/msg00233.html (11,397 bytes)

16. Re: [Amps] 4CX1000A (score: 1)
Author: "Roger (K8RI)" <k8ri@rogerhalstead.com>
Date: Sat, 28 Jan 2012 19:55:32 -0500
For a small fortune I'll sell you a batch of them that are already in a mint Hallicrafters HT-33B with the 8295A ceramic Pentode, plus spares. <:-)) 73 Roger (K8RI) __________________________________
/archives//html/Amps/2012-01/msg00239.html (9,632 bytes)

17. Re: [Amps] 4CX1000A (score: 1)
Author: "Roger (K8RI)" <k8ri@rogerhalstead.com>
Date: Sat, 28 Jan 2012 19:57:06 -0500
I think you will find that most Tetrodes in this range *will* have a range of reverse screen current. To me that means normal The Pentode is a different animal. They were designed specifically to add
/archives//html/Amps/2012-01/msg00240.html (11,712 bytes)

18. Re: [Amps] 4CX1000A (score: 1)
Author: "Roger (K8RI)" <k8ri@rogerhalstead.com>
Date: Sat, 28 Jan 2012 21:34:21 -0500
My modern one which runs the legal limit with lots of overhead for digital is a hefty 100# while the old HT33B that only runs 1KW DC input (2 KW PEP) outweighs it by 13# for a total of 113# for less
/archives//html/Amps/2012-01/msg00247.html (10,083 bytes)

19. Re: [Amps] 3CX400/3CX800 Socket (score: 1)
Author: "Roger (K8RI)" <k8ri@rogerhalstead.com>
Date: Mon, 30 Jan 2012 18:33:00 -0500
I've also used the fin(s) out of old copper heat sinks for these as well as for the "hairpin" parasitic suppressors. it's easy to cut with a pair of hears. NOTE many metal shears will leave a rough o
/archives//html/Amps/2012-01/msg00304.html (8,665 bytes)

20. Re: [Amps] Different amp recommendations (score: 1)
Author: "Roger (K8RI)" <k8ri@rogerhalstead.com>
Date: Wed, 08 Feb 2012 15:42:57 -0500
There are a number of them. Emtron from Australia, Acom from Europe are two. I can run the legal limit on SSB for long winded rag chews and the tank doesn't even get hot. OTOH the tank coil is much l
/archives//html/Amps/2012-02/msg00060.html (8,886 bytes)


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