Price List for
Parasitic-Suppressor Retrofit-Kits include nickel-chromium-iron alloy wire; 430'F / 221'C tin-silver solder and nichrome soldering flux, glitch protection and RF-NFB resistors; capacitors; 200a-peak glitch protection diodes; instructions; diagrams and an easier-to-understand, condensed version of the Oct 1988 QST article.
Retrofit-kits are available for the majority of contemporary grounded-grid amplifiers. If you need a special kit, telephone me and we can probably arrive at a solution. Amplifiers up to 100kW PEP have been retrofitted with low VHF Q parasitic suppressors.
For more information on intermittent VHF parasitic oscillation and some photographs of parasitic-damaged amplifier parts, see QST magazine, Parasitics Revisited, Part-1: September 1990, page 15 and Part-2: October 1990, page 32.
|
Suppressor Retrofit-Kit for: |
Price |
per additional amplifier add |
|
(1) 3CX1200A7/3-1000Z |
$ 14.50 |
$5.50 |
|
(1) 3-500Z, 3-400Z |
13.50 |
4.50 |
|
(1) 8873 [SB-230] |
13.50 |
4.50 |
|
(1) 8877 |
14.50 |
5.50 |
|
(2) 3-500Zs, 3-400Zs |
14.50 |
5.50 |
|
(2) 572Bs or 811As |
12.50 |
4.50 |
|
(2) 3CX800A7s |
16.50 |
5.50 |
|
(2) 3CX800A7s - Titan 425 |
16.50 |
5.50 |
|
(2) 8873s, 8874s |
15.50 |
5.50 |
|
MLA-2500 |
16.50 |
6.50 |
|
(3) 8874s |
15.50 |
6.00 |
|
(4) 572Bs or 811As |
16.50 |
6.00 |
|
4-1000A {up to 2-tubes} |
17.50 |
10.00 |
|
3K-A, 2K-4 etc. |
15.50 |
5.50 |
|
2K Classic, & "X" |
15.80 |
6.00 |
Prices do not include shipping
Shipping: To U.S. addresses: $1.00 per kit. Air Mail to the Western Pacific, $5.00 per kit; to Europe, $4.50 per kit.
CA residents add 7.25% Sales-Tax. Shipping charges are not taxable.
All prices are subject to change without written notice. If our costs increase, we increase prices. If our costs decrease (yeah, right), we decrease prices.
Guarantee Our suppressor retrofit kits are guaranteed to make your amplifier more stable. If you feel your amplifier was not made more stable by the retrofit kit, you owe us nothing for the retrofit kit - or, a refund will be made if u paid.
Most of the parasitic-suppressor retrofit kits are designed to make their respective amplifier-tubes safe to use with approx. 100W of drive power. This benefit is accomplished by adding RF negative-feedback [RF-NFB] resistors (Rc) n series with a G-G amplifier's cathode-input circuitry. This will prevent sensitive tubes like the 8874 and 3CX800A7 from being damaged by today's typical approx. 100W transceiver. RF--NFB works better than amplifier to transceiver ALC. RF--NFB also increases amplifier linearity and stability. If you own a transceiver that can not deliver approx. 100w, you can leave out, or reduce the value of, the RF-NFB resistors during the modification procedure.
If you know how to solder and you can read English, you can probably install a suppressor retrofit kit. Anyone who can build a Heathkit® can do it. If you have a problem or question, you can call me on the telephone. When I am not available, my answering service takes messages. I return all calls on my dime.
Retrofit-kit Installers If you would rather have low VHF-Q parasitic suppressors installed professionally, this service is available from:
Steve Wedge, W1ES, 6 Vose Hill Road, Westford, MA, 01886, 508 692-8501.
Curt Eversole, KE9NJ.
Jim Colville W7RY e-mail <[email protected]>, 509-466-6972.
Worth Hewitt, K5JLI, Houston, TX 1-800-819-2742 or [713] 351-2742.
>>>>Amplifiers that are shipped via UPS--Surface are virtually certain to be subjected to severe inertia forces [dropped/thrown]. UPS--2nd Day handles packages somewhat less roughly. Glass amplifier tubes should be shipped in separate, large, boxes. Always put packing pellets in partly-filled sealed bags to avoid settling during shiping.
Other Items
Small parts are shipped postpaid if they are ordered with a retrofit-kit since they can be included in the padded mailing bag that the kit is shipped in. If small parts, or an item that comes in a bottle, are ordered separately, add $1.00 for a padded mailing bag and postage. [pn-14]
Electrolytic Filter Capacitor Equalizer-Resistors See: Circuit Improvements for the Heath SB--220 Amplifier in the November and December 1990 issues of QST. Each 10ºC increase in the operating temperature of aluminum electrolytic filter capacitors reduces their useful life expectancy by about one-half. The SB-220 uses (8) 30k ohm equalizer resistors. These resistors generate so much heat they partially melt the plastic holders and shorten the life of the electrolytic filter capacitors. The 30k ohm resistors should be replaced by 100k ohm to 150k ohm resistors. Individual 100k-ohms, 3W, 500v max., Matsushita equalizer-resistors [pn--86] are $0.48 each. These resistors are stable, accurate and reliable. This modification is advisable for other amplifiers that use <50k-ohms electrolytic capacitor equalizer-resistors such as the SB--200, BTI, Henry 2KD-5 and 1KD-5. It is also appropriate to retrofit them in the HV supplies of older ETO/Alpha amplifiers and Dentron amplifiers which use (unstable) carbon-composition resistors.
RF bypass cap. for anode supplies:, 2700pF, 9000V-test, 3000DCWV, Y5P dielectric, p/n 96, $1.38.
High-Speed Relays/QSK: (see 1/94 QST, "The Nearly Perfect Amplifier"] The Heathkit SB-220, Kenwood TL-922, and many other amplifiers need higher-speed relays so that they will not hot-switch with modern, fast-switching radios. If you would like to read: QSK for the TL--922 and SB--220 With Circuit Improvements for the TL-922, the orig. manuscript is available on my Web site. See Figure 7. // This QSK circuit has been added to other amplifiers such as the Drake L4B. Since its switching speed is approx. 2mS, the QSK circuit works well for SSB-VOX, AMTOR and for CW up to about 35wpm. For 100wpm computer--CW, a PIN-diode QSK circuit should be used instead.
Solid-State Parts: NEC PS2505-1 or PS2501-1 optoisolator; 80V �300% I-gain; 6µS, 80mA max. input; $1.00 [pn--44.3]. HV switching transistor; NPN, 300V, 0.5A, $0.35 each [pn--44] -- includes base-bias resistors; 10A 100V NPN flat-pak transistor for electronic cathode bias switch (Q1 in ECBS) [pn-44.1, $2.30 each; transient V suppressor for ECBS (D1), 1.5CE51A - 1500W peak,Vz= 51v [pn-44.4] $1.10.
High Speed Relays: Matsushita RF reed-relay, 1mS, SPDT, Rh-Au contacts, RSD-12V, shielded, 150W at 50-ohms [pn-44.5] $11.00.
A parts kit for adding QSK/high-speed switching is $21 [pn-47]. The Jennings RJ-1A high speed vacuum relay is not included.
Silver solder & nichrome soldering flux: For use with a soldering iron. The silver solder flux is supplied in a single-drop 10cc dispenser bottle. It is intended for soldering nichrome, stainless steel, copper, steel, brass, et cetera; p-n 41.1, $0.75 each. WARNING: The residue from this flux is corrosive and must be removed with warm water and a toothbrush after soldering. The flux is poison and it eats skin.
The 430ºF/221ºC, eutectic, silver solder we supply in the retrofit-kits is: highly corrosion resistant, approx. 3.5-times stronger than 60/40 tin-lead electronics solder, flows well on difficult to solder materials, and contains no toxic hazard. sIt is FDA-approved for use on food utensils. It surpasses Mil-Spec purity standards. 1/8" diameter silver solder: $1.90 per foot [305mm] {pn--41.2}. This material works well with liquid rosin flux for soldering copper, silver, tin, brass, pins on 3-500Zs, and printed circuit boards. It is excellent for use on antennas and ground systems. It also works well for soldering aluminum by using J. W. Harris® aluminum soldering flux {available at welding supply shops}.
Low VHF-Q/Low VHF-Rp material: Ni-Fe-Cr #20 [1mm] wire: 4ft coils, pn--45, $1.00 each -. DC R = around 0.8 ohms per foot. Nichrome ribbon, 0.25 inch by 4-mil, $0.50 per foot.
Ordering Information
Each suppressor retrofit kit order should include the amplifier model and the quantity of such amplifiers that you are modifying. I would also like to have a telephone number where you can be reached in the evenings or on weekends--in case I have a question. If you have a question, please feel free to telephone me up to 8pm CA time.
Methods of Payment . Personal cheques or money-orders payable in U.S. Dollars; U.S. "greenbacks", suitably wrapped in newspaper comics or in aluminum foil are ok.
Your cheque is not deposited until after your order is mailed. Unless otherwise requested, small refunds are normally made in extra silver solder or cash. Large refunds are made by cheque payable in U.S.$.
--Address--
Richard L. Measures, AG6K
6455 La Cumbre Road
Somis, CA, 93066 -- 805 386 3734
Overseas orders: Please tell us what to write on the package to help your retrofit-kit pass smoothly through your country's customs or import-duty department.