Greetings

conducted by: Richard L. Measures, AG6K - telephone, [805] 386-3734 (voice). To penetrate the telemarketer filter, ring twice, hang up, press "Redial". If I am home, I will answer. . If not, please leave your telephone # and I will return the call.

6455 La Cumbre Road, Somis, CA, 93066 / E-mail:

2@mail.vcnet.com

last revised 7 July, 2002.

What's new and semi-new?:

• The OOO card. See Figure 27 below.
• Kodachrome transparency of me at the age of c. 3.9, standing with my parents in a field of wildflowers at the South end of the San Joaquin Valley in 1944. Like c. 1969, there was much rainfall and sunspots c. 1944. Twelve years later, I built my first amplifier. Maybe it was the sunspots?
• VHF parasitic arced bandswitch from BTI 3-1000Z amplifier compared with new bandswitch. Courtesy of Dan, KM6UC. Replacement bandswitch: Multi-tech Industries; 64 So. Main or PO Box 159; Marlboro, NJ 07746; 732-462-6100 < www.multi-tech-industries.com > ; Attn: Skip Coleman; p/n R862L0430X02. BTI.bsw,JPG. Multi-tech builds a line of bandswitches that are suitable for tubes-with-handles amplifiers: < http://www.multi-tech-industries.com/mod_92.gif >. The Model 92 switches are rated at 100ADC and 24kVDC. For RF use, those ratings translate to roughly 25Arms and 15kV-peak at 20MHz. The Model 92 switch is not reasonably priced in small quantities.
• Figure 24.1 -- Photo of AL-1500 anode circuit showing the lack of a VHF parasitic suppressor.
• Source of high-pot tester power supplies: http://www.emcohighvoltage.com/ourprods.htm
• Figure 23 - toasted TL-922 bandswitch photo in 10-1990 QST.
• item 25, General Instructions for installing low VHF Q suppressors.
• "The Good, the Bad, and The Ugly". The story of "The Plywood Box ".
• photos of Ugly amplifiers. .plus drawings of PEM nuts. [The original "Plywood Box" 20db amplifier is now included in the Ugly Amplifier photographs. (courtesy of W6RD, Chuck and Terry, W6RU)]
• [AMPS] mailing-list is a source of amplifier discussions. <www.contesting.com/_amps/>.

High Potential Tester (a.k.a. 'high-pot.')
Circuit Improvements and Maintenance Procedures for the TS-830S
Circuit Improvements for the TS-430S
Circuit Improvements for the TS-440S
Circuit Improvements for the TL-922 [condensed version]
QSK for the TL-922 and SB-220 With Circuit Improvements for the TL-922

"Circuit Improvements for the Heath SB-220 Amplifier" (updated manuscript for Nov.-Dec., 1990 QST article).

Fyler, G. W. ''Parasites in Transmitters'', Institute of Radio Engineers journal. Sept. 1935. Conclusions.

"Improved Anode Parasitic suppression for Modern Amplifier Tubes", {October 1988 QST,}

"Adding 160 Meters to HF Amplifiers" {1/89 QST}

"A Balanced Balanced Antenna Tuner" {2/90 QST}

"Circuit Improvements for the Heath SB-220 Amplifier" (updated manuscript for Nov.-Dec., 1990 QST article).

"The Nearly Perfect Amplifier" (1/94 QST)

"Amplifiers"

• Part 1 -- Introduction, Classes of Operation, Amplifier Design Considerations, Tubes vs. FETs, Grounded-Grid Versus Grid-Driven, Cathodes, Filament / Heater Considerations.
• Part 2 -- Grid Protection in G-G Service, Glitch Protection, Design Considerations for Indirectly-Heated Cathode Tubes, Safety Devices, Power Supplies, Transformer Ratings.
• Part 3 -- (power supplies) Changing Voltage, Transformer Insulation/Potting, Biasing, Class AB1 grid bias, High Speed RF Switching, Solid State Component Ratings, Breakdown V. Testers / High-Pots, VHF Stability, Designing VHF Parasitic Suppressors.
• Part 4 -- ALC, Capacitors and RF Current, Tuned Circuit Q, Tuned Input Circuits for Class AB2 Cathode-Driven [grounded-grid], Tank Circuits, Skin Effect and Current Capability, Anode HV RF Chokes, Determining Bypass-C, DC Blocking Capacitors, Vacuum Components, Grounded-Grid Amplifier Tune-up, Class AB1 Design Considerations, Grid-Driven Class AB1 Amplifier Neutralization and Tuneup, Distortion, Notes on Measuring Power, Tube Ratings.
• Part 5 Calculating Tank Values, Excel 4 tank calculator work sheet. note: The formulae used are the approximate ones used by Eimac in *Care and Feeding of Power Grid Tubes" (which ignore the Q-contribution of C2) . As a result, the values will be slightly off.
• The Funderberg gold sputter test.
• ---------------------------
• Figure 1 (step-start)
• Figure 2 (glitch protection)
• Figure 3 (spst-switchable, dual output V, rectification circuit)
• Figure 4 (Class AB1 electronic-switched grid bias supply)
• Figure 5 (Class AB1 grid input circuit)
• Figure 6 (breakdown-V tester / "high-potential tester / "high-pot". / Source of high-pot DC/DCpower supplies: http://www.emcohighvoltage.com/ourprods.htm
• Figure 7 (high speed T-R switching)
• Figure 7B (high speed T-R switching, higher resolution)
• Source of Jennings RJ-1A and Kilovac HC-1 vacuum relays: http://www.mgs4u.com/relay.htm The price is $32.50.
• Figure 8 (screen V regulator)
• Figure 9 (tuning pulser)
• Figure 10 (shunt-type screen V regulator)
• Figure 11 (anode contactor for high power HF amplifiers)
• --------------------------------------------
• Other illustrations, info, and photographs
• Figure 12 (Rp measurements for different types of VHF suppressors)
• Figure 13 (VHF-resonant circuits in HF amplifiers)
• Figure 14. Arced bandswitch contact on Fl-2100 bandswitch, courtesy of Will, K6NDV.
• Figure 15 (arced bandswitches) [AL-80 bandswitches courtesy of Richard P. May, KC0HH, <rjmay@iguana.ruralnet.net> and George Drysdale, WA6ALQ, gdrysdal@ix.netcom.com. ETO bandswitch courtesy of Bud Henley] Also see page 33 of "Parasitics Revisited" in the October 1990 issue of QST for a photograph of a VHF parasitic-arced TL-922 bandswitch.
• Figure 16 (arced bandswitch wafer removed from a 3CX1000A7 amplifier). Bandswitch courtesy of Charles M. Alessi, W6IEG. Note: this is a large, high-resolution photograph of a large bandswitch.
• Figure 17 (arced bandswitch removed from a MFJ-Ameritron AL-82 amplifier)
• Figure 18. Excerpt from "Calculating Power Dissipation in Parasitic-Suppressor Resistors", March, 1989 QST, page 7, 'Finding Impedance by Solving for Admittance'. .® The American Radio Relay League, Inc.
• Figure 20. Circuit Improvements for NCL-2000.
• Figure 21. Parasitic-arced bandswitch removed from Ameritron/MFJ AL-82 (2, 3-500Z) amplifier.
• Firgure 22. SB-220 Diagram. 2x magnification. Print with reduction to fit on legal size paper.
• Figure 23 - Burned TL-922 bandswitch photo, on page 33, "Parasitics Revisited", October, 1990 *QST*.
• General Instuctions for building low VHF Q parasitic suppressors, page 1-4.. General Instructions P. 5 drawing.
• map of QTH
• Figure 24 -- Photo of gold-sputtered 8877 (s/n HSZ 501) with mix of gold meltballs.(smallest particles) and sawing residue (largest particles). This 8877 was removed from an AL-1500 amplifier that has reportedly gone through four 8877s.
• Figure 24.1 -- Photo of AL-1500 anode circuit showing the lack of a VHF parasitic suppressor.
• Figure 25 -- TL-922 diagram
• Figure 26 Diagram. Double, low Rp, parasitic suppressors for two 3-500Zs. (diagram from parasitic suppressor retriofit kit)
• Figure 27. Official Observor Observor Card. Use this to reply to anal OO cards.

If you find a glitch in Amplifiers, a fuzzy explanation, a technical error, or a typo, please let me know. If you think I left something important out, please say so.

The title 'Amplifiers' is somewhat misleading. Only linear amplifiers are discussed in detail. If you are interested in building a Class B or Class C amplifier, 'Amplifiers' is not going to be of much help.

Low VHF-Q parasitic suppressor retrofit-kits for most types of amplifiers -- both mfg. and home-brew. Price List--Information Sheet

• We receive orders that have no mailing address. We can not send an order until we receive a mailing address.

High-speed switching parts-kit for retrofitting an existing non-QSK amplifier. p/n 47 (See January, 1994 QST , "The Nearly Perfect Amplifier", page 33---or see Figure 7 - 7B above) The kit includes the Matsushita 1mS RF reed-relay (RY2), the NEC optoisolator (Q2), the 6A transistor (Q1), two (1 plus a spare) 1500w 51v transient voltage suppressors (D1), needed resistors/capacitors and a 300v 0.5a NPN switch transistor for controlling the amplifier with a radio that supplies +LV on TX to key the amplifier. Untested, used, Jennings RJ-1A RF output vacuum-relays (RY1) are available from Fair Radio Sales 419-227-6573. The price is approximately $35 for a used RJ-1A. . // The price of the parts kit is $21 plus $1 for shipping to US addresses .// . I recommend testing the RJ-1A before use. A relay with a good vacuum will withstand at least 3500v across the open contacts -- with under 2 micro amperes of leakage. Note: A bad vacuum in RY1 can destroy RY2.. High Speed Relay Mounting Instructions.

High-reliability, high-stability MOF resistors for electrolytic filter capacitor equalizer R service. Matsushita, 100k-ohm, 3w, 500V max. matched within 0.05%, part number 86, $0.48 each.

We no longer sell telephone RFI filters. However, you can buy the parts for them from Mouser Electronics [1-800-346-6873]. The part number for the 470 micro-Henry inductor is 43LS474. The current price for 100 is $29. 100 inductors will build 50 single-section filters or 25 double-section filters. The value of the [1000pF to 3000pF] capacitors is extremely non-critical. The capacitors have little effect on the suppression ability of the filters--except perhaps on 10m. Put one inductor in series with each side of the telephone line. The filter should be close to the telephone. If the interference persists after one filter is installed, try a double-section filter. Phone filter Diagram.......phone filter Instructions.

We no longer sell HV bypass caps because our cap supplier stopped carrying them.

- The Background Story behind the following story-

On page 24 in the February, 1996 issue of QST, Editor Mark Wilson, AA2Z, writes:

"The rebuttal that Rich provided was, in our view, repetitious of his articles that were previously published in QST. Readers who are interested in knowing more about his design philosophy have a wealth of material in print with which to work."

Maybe the Rebuttal is repetitious of the QST articles, or perhaps not. I thought that the people who read QST might like to have the opportunity to decide this matter for themselves. After all, Mark Wilson works for them. It's probably a good idea for an employer to check up occasionally on employees.

Mark Wilson said, "We should have sent 'The Nearly Perfect Amplifier' for technical review and dealt with any questions about its accuracy prior to publication, ...." Apparently, Mark expects people to believe that QST does not perform an adequate technical review of articles with its own technical review group. Unsliced bologna. No article gets accepted without the approval of QST's technical review group. Mark seems to have forgotten that "The Nearly Perfect Amplifier" did receive a final technical review just before it went to the printer. The final reviewer was QST's present Editor, Mark Wilson.

Mark Wilson suggests that there were some technical errors in the article -- but he doesn't mention a specific error to support his allegation. So far, I have become aware of one technical error in the article. Eimac recommends a Q of 5, Not a Q of 2, for the tuned input of a G-G amplifier. The person who found the error was the author of the article. If you find another technical error in the article, please telephone me, collect if you like, or E-mail me.

I apologize for the length of the Rebuttal. It is longer than I would have liked. However, the Rebuttal is designed to address each point of contention in the September. 1994 QST [pages 71-74] critique. There was much material to cover. The critique by the six "contributors"/critics (Fred Telewski, WA7TZY; Tom Rauch,W8JI; Reid Brandon,W6MTF; Bill Clemow, KE7CX; John Fakan, KB8MU; and Steven Katz, WB2WIK) amounted to 5500 words -- an all-time record for QST.

A letter from Eimac® (text) is mentioned in the Rebuttal. Letter from Eimac® (photocopy)

photos of Plywood Box; Top, Front , Chassis , Power Supply

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