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1. Re: [Amps] Internal QSK-5 (score: 1)
Author: "Joe Subich, W4TV" <lists@subich.com>
Date: Sat, 31 Jan 2009 23:12:38 -0500
Wrong ... the fuse lamps protect the transceiver if the "receive" PIN diodes or HV power supply fails and amplifier RF gets through. They are also there to prevent the amplifier from running away in
/archives//html/Amps/2009-01/msg00384.html (10,216 bytes)

2. Re: [Amps] Internal QSK-5 (score: 1)
Author: "Joe Subich, W4TV" <lists@subich.com>
Date: Sun, 1 Feb 2009 12:02:56 -0500
Kim, I was using the schematics for the QSK-5 at BAMA and comparing the functions to the DEO QSK-1500 that I was very familiar with a lifetime ago <G>. The PIN-5 should be very similar to internal ci
/archives//html/Amps/2009-02/msg00010.html (14,632 bytes)

3. Re: [Amps] New Ameritron Solid State Amp? (score: 1)
Author: "Joe Subich, W4TV" <lists@subich.com>
Date: Sun, 8 Feb 2009 11:30:49 -0500
Looking at HRO the price difference is more like $400 when you compare the HRO sale price and the Ameritron list price. Since the Ameritron amplifiers are typically discounted 10% from list, the rea
/archives//html/Amps/2009-02/msg00204.html (13,463 bytes)

4. Re: [Amps] ALS-1300 (score: 1)
Author: "Joe Subich, W4TV" <lists@subich.com>
Date: Mon, 9 Feb 2009 17:03:59 -0500
The problem is that Ameritron is sloppy with their design. The amplifier board in the ALS-600 is almost a part for part copy of the Helge Granberg/Motorola application note EB104. The amplifier has
/archives//html/Amps/2009-02/msg00250.html (9,993 bytes)

5. Re: [Amps] Nichrome wire for suppressors (score: 1)
Author: "Joe Subich, W4TV" <lists@subich.com>
Date: Wed, 11 Feb 2009 11:03:29 -0500
I don't think that anyone is arguing that resistive loading isn't a valid and useful approach to dealing with parasitics. Commercial amplifiers of all kinds have used that approach, including nichro
/archives//html/Amps/2009-02/msg00311.html (14,010 bytes)

6. Re: [Amps] ALS-1300 (score: 1)
Author: "Joe Subich, W4TV" <lists@subich.com>
Date: Thu, 19 Feb 2009 10:17:19 -0500
Ameritron had an ALS-1300 with clear cover in their display at the Orlando Hamcation last weekend. The physical construction looks reasonable - perhaps a bit above normal for them. It is most certai
/archives//html/Amps/2009-02/msg00557.html (13,080 bytes)

7. Re: [Amps] An Extra Thank You! (score: 1)
Author: "Joe Subich, W4TV" <lists@subich.com>
Date: Thu, 5 Mar 2009 16:11:14 -0500
Gain = 10 * log(Pout/Pin) = 10 * log(450/20) = 10 * log(22.5) = 10 * 1.352 = 13.5 dB Efficiency (assuming grounded grid) = Pout/(Ip*Vp+drive) You don't give the plate voltage so I'll use 2000V as a
/archives//html/Amps/2009-03/msg00167.html (10,549 bytes)

8. Re: [Amps] An Extra Thank You! (score: 1)
Author: "Joe Subich, W4TV" <lists@subich.com>
Date: Thu, 5 Mar 2009 19:42:10 -0500
In grounded grid the drive is in series with the output. Thus the drive power (less power lost in grid current and heat in the input circuit) adds to the output. Adding the drive power to the plate
/archives//html/Amps/2009-03/msg00194.html (10,476 bytes)

9. Re: [Amps] SB200 on 6m & my take (score: 1)
Author: "Joe Subich, W4TV" <lists@subich.com>
Date: Fri, 13 Mar 2009 17:43:59 -0400
Using a 572B in an 811-A socket is hardly a test. The 572B is rated for significantly higher plate voltage and plate dissipation than the 811A. Even the worst of the "572B" tubes should perform sati
/archives//html/Amps/2009-03/msg00401.html (14,409 bytes)

10. Re: [Amps] QSK-MASTER (score: 1)
Author: "Joe Subich, W4TV" <lists@subich.com>
Date: Wed, 8 Apr 2009 14:26:20 -0400
The QSK Master looks like a scaled up version of the AD5X QSK switch: http://www.ad5x.com/images/Articles/QSKrevB.pdf I'd start there ... 73, ... Joe, W4TV ___________________________________________
/archives//html/Amps/2009-04/msg00087.html (7,257 bytes)

11. Re: [Amps] 6 Meter Amp (April 2008 QST) Question (score: 1)
Author: "Joe Subich, W4TV" <lists@subich.com>
Date: Wed, 3 Jun 2009 17:03:24 -0400
The article also states the parts list, etc. is available at: www.arrl.org/files/qst-binaries A check of the ARRL site reveals: www.arrl.org/files/qst-binaries/Gilbert%20et%20al%200408.zip 73, ... J
/archives//html/Amps/2009-06/msg00008.html (8,260 bytes)

12. Re: [Amps] HV for Ameritron QSK-5PC (score: 1)
Author: "Joe Subich, W4TV" <lists@subich.com>
Date: Mon, 13 Jul 2009 22:14:18 -0400
That's only enough reverse bias for a matched load in a 50 Ohm system. With 2:1 SWR the peak of the RF crest is almost 800 V (535 - 540V RMS). 73, ... Joe, W4TV _____________________________________
/archives//html/Amps/2009-07/msg00193.html (8,758 bytes)

13. Re: [Amps] Grounded Grid (Screen) 4CX250B power gain (score: 1)
Author: "Joe Subich, W4TV" <lists@subich.com>
Date: Tue, 21 Jul 2009 15:27:30 -0400
I seriously doubt that adaptive predistortion is covered by any enforceable patent and it is certainly not limited to digital modulation. Phillips, Marconi and others, used predistortion with analog
/archives//html/Amps/2009-07/msg00246.html (11,817 bytes)

14. Re: [Amps] grounding grids (score: 1)
Author: "Joe Subich, W4TV" <lists@subich.com>
Date: Wed, 29 Jul 2009 12:22:22 -0400
The grid resonance of the 3-500Z and similar tubes has been measured well above 100 MHz. There is no need to "float" the grid. In fact, floating the grid will lower the grid resonance by increasing
/archives//html/Amps/2009-07/msg00357.html (11,808 bytes)

15. Re: [Amps] grounding grids (score: 1)
Author: "Joe Subich, W4TV" <lists@subich.com>
Date: Wed, 29 Jul 2009 17:49:20 -0400
The Grid is far from "well grounded." With 220 pF in series, the grids are above ground by 25 Ohms (Xc) at 28 MHz and 206 Ohms (Xc) at 3.5 MHz (the design operating range of the SB-220) ignoring the
/archives//html/Amps/2009-07/msg00367.html (15,073 bytes)

16. Re: [Amps] grounding grids (score: 1)
Author: "Joe Subich, W4TV" <lists@subich.com>
Date: Wed, 29 Jul 2009 21:35:47 -0400
Pin 2, 3 and 4 of each tube are connected together internally. Each of the three grid pins is bypassed to ground. This combination of RF chokes and capacitors provides a predetermined level of negat
/archives//html/Amps/2009-07/msg00377.html (18,724 bytes)

17. Re: [Amps] grounding grids (score: 1)
Author: "Joe Subich, W4TV" <lists@subich.com>
Date: Wed, 29 Jul 2009 21:45:52 -0400
Not in the SB-220, the grid circuit is a 1 mH RF choke bypassed with three 200 pF disk ceramic capacitors. The SB-200 used a single 200 pF capacitor to bypass the grids of the 572B with a single 33
/archives//html/Amps/2009-07/msg00378.html (19,359 bytes)

18. Re: [Amps] [Spam] Re: grounding grids (score: 1)
Author: "Joe Subich, W4TV" <lists@subich.com>
Date: Thu, 30 Jul 2009 01:12:25 -0400
That is not the reason Heath gave for the design. Simply opening the grid lead does not and will not protect the grid as a HV arc can and will damage (puncture) the grid and continue on to the catho
/archives//html/Amps/2009-07/msg00395.html (23,181 bytes)

19. Re: [Amps] grounding grids (score: 1)
Author: "Joe Subich, W4TV" <lists@subich.com>
Date: Fri, 31 Jul 2009 01:50:41 -0400
At what frequency since the impedance between the grid and common (ground) changes by a factor of nearly 10:1 between 3.5 MHz and 29.7 MHz? What other steps were taken to hold the -2dB feedback cons
/archives//html/Amps/2009-07/msg00427.html (12,975 bytes)

20. Re: [Amps] grounding grids (score: 1)
Author: "Joe Subich, W4TV" <lists@subich.com>
Date: Fri, 31 Jul 2009 02:05:11 -0400
This would also indicate a value to removing the negative feedback circuit with modern 100 Watt output solid state transceivers. With their three finals, the TR-3 and TR-4 were capable of 150+ watts
/archives//html/Amps/2009-07/msg00428.html (12,931 bytes)

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