homebrew roller inductor. The difference between this type of variable inductor and a "roller inductor" is that there are no unused windings hanging in the circuit like you have on . There are three versions of this antenna available: a 41-ft. HomebrewTalk Sponsor Market HomebrewTalk Sponsor Giveaways. Applications Double balance mixers, broad-band …. You see big roller variable inductors in antenna matching circuits, but it is doubtful that these inductors would be suitable for . Inductors, Roller, W8JI (part way down this post): . Two wipers are approximately 1/8” in diameter. The set screw on the inductor's knob may be electrically hot during use, you may want to cover it with a drop of plastic glue or silicone after tightening. It has only one ¼" diameter shaft connection. Home Brew won by Bill (VK2ZCV) Port for 2-M Yagi Antenna DesiB1 Prize : Cordless Drill Men's Lucky Door Basket of Bits & Pieces Ross VK2DVZ …. The two Johnson roller inductors I used in my homebrew balanced-L antenna tuner have a 3/8-inch O. Antenna Tuners: Setting the Record Straight. Antennas, Field Reports, News, Portable, POTA, QRP, Reviews. The first is in series with the connection to the Whip and the second is to ground. My homebrew vertical multiband hf antenna. The operation of this network depends on the fact that C 1 can be used to adjust the diameter of the constant conductance circle around which the intermediate impedance is moved by the inductor. 3/4 thin wall PVC will admit 5/8 plunger. Don't laugh, this tuner has been in continuous operation …. While the simpler circuit of our other motor controller kit …. Home brew HF amp by an expert, 10-80 + possible 160m, 4-400A Eimac tubes, roller inductor, vacuum variable caps, on casters, $500 (Pick Up) ---. Science Physics Q&A Library • Part A The mass of a regulation tennis ball is 57. Components Engineered for Amateur Radio. You could change to another design. One of the geared motors turns the roller coaster inductor, the other a variable capacitor. Welcome to the Amateur radio Manual antenna tuners page. Type: homebrew roller inductor. - 80m is a high-Q antenna giving a limited usable bandwidth of about 65Khz @ ~2:1 …. I used electric fence insulators to make the spacers, about 3 1/2" spacing and the total length of the feed line is about 36 or 40 feet (I'll get a better measurement). The original main roller inductor’s mounting plates were much too high so new brackets were made to bring the inductor height down. 18 Aug 2020 6:20 PM Dave Cason (Administrator). RADIODAN W7RF My Henry 3K Classic X MKII. The tapped inductor cannot always be set exactly to the desired matching inductance. Even tin plated copper wears out with roller inductors. Wholesale Customers - Approved account holders only. SILVER plated variable air capacitor high Q factor 2KV. Don't laugh, this tuner has been in continuous operation for over 16 years. An inductor is in series with an 80. If a balun is going to be installed, allow enough room behind the roller coil for mounting the balun. Recall the words "Homebrew Radio" in the title of this article. A true RF choke or Current Balun is also used. Second layout RF deck- stacked cap give more room for the magnetic fields crated by the roller inductors. How to make: L is a hollow coil, and a 1. Here are some links to pictures of my homebrew tuner using used components from various sources, with the exception of the gold plated roller inductor …. Homebrew Catcher Bug Antenna. New Old Stock * No longer available for export. We will be debuting our new look on Wednesday so please join us then. That will complete the first phase of the project. The slot width, t, should be a minimum of 3/8 inch. Overall, insertion loss in tuner MK2 is between 0. 5 to 3 amps using SSB (based on the average human voice without compression). Homebrew Equipment A place to show, design and discuss the weird and wonderful electronic …. I am currently using one of these roller inductors in a homebrew …. For 100 W or less the plate spacing of most available air-variable capacitors is probably adequate. Among other components, it contains a water cooled 3CW30000H7 …. Home Brew HF Vertical Will cover 80M to 20M HF bands antenna has a small …. HRO-5A1 - At the end of WWII, most manufacturers had …. Me forgetting to tell post security. My HF antenna setup for the past few years has consisted of random lengths of magnet wire thrown into trees. Perhaps more than an inch is a good idea. This world-famous 3 KW MFJ-989C VersaTuner V features two massive transmitting capacitors and a roller inductor with a three digit …. | Build It Yourself Electronics …. It is made with a wood enclosure …. Modification / homebrew for Heathkit sa-2040: Fix for loose roller inductor Heathkit SA-2040. ANTENNA TUNER, HOMEBREW 80-10 Roller Inductor - $39. deluxe versa tuner roller inductor HF antenna tuner MFJ 962 D Antenna Tuner 17' Whip Resonant Antenna FIELD TEST ~ NO Tuner! ~ …. THIS IS A LITTLE BIT ABOUT MYSELF AND MY WORLD. EF johnson matchbox L network T network. Each component is defined, and several common …. 10 Gallon Fully Draining Cone Bottom Inductor Tank (55 Degree) Ace Roto …. The Procomm PCF Series monoband antennas are tried-and-true. It is a beautiful silver plated coil in excellant shape that measures 13. part: 229-202 prices Specifications 229-202: country/region of manufacture: USA; mpn: 229-202; brand: JOHNSON. 3 Johns, "Homebrew Your Own Inductors", QST, August 1997, pp. A Homebrew Antenna Tuning Unit inductors, a large four-ganged switch and several unidentified components are obvious but, to my initial surprise, no …. This keeps the RF resistance of the coil at its practical minimum and allows reasonably high Q to be maintained at the low end of the inductance range. Using the amplifier’s frame to bend the …. HOMEBREW ANTENNA TUNER PROJECT (PARTS OR REPAIR O…. The purpose of NVIS is to communicate locally and regionally, out to a few hundred miles, with moderate power, simple antennas, and no skip zone. (Jan 18, 2015) - - Members of the MARC and amateurs around the area attended MFJ Day at DX Engineering on Saturday, January 10th. DIY roller Inductor? Discussion in 'Homebrew and Kit Projects' started by KK6WKK, Jan 25, 2016. Date: Sat, 15 Oct 2005 07:38:57 -0700 Message-ID: [email protected] I think the next part will be …. Find many great new & used options and get the best deals for Homebrew 1K Antenna Tuner,Military Roller Inductor,Big Air Variable Capacitors at the best online prices at eBay! Free shipping for many products!. I also tuned the ground wire with an 18 uh roller inductor that allowed me to move +/- the center frequency, didn’t’t try but a fixed coil with a switch. Grounding of Antenna An 8 or 10 foot ground rod should be installed at the base of this …. The only frequencies you might run into problems with a roller inductors would be 50 MHz (6 meters). Looking for plans for a small QRP tuner. My homebrew HF antenna and Yaesu radio. FS Tucker 3K roller inductor tuner - tuner. I can always tap the coil more finely and use a bigger bandswitch. Here's the inner workings of a MFJ 969 roller inductor antenna tuner. Homebrew 144 MHz Coaxial Dipole Antenna. ANTENNA TUNER, HOMEBREW 80. Adjunct membership is for researchers employed by other institutions who collaborate with IDM Members to the extent that some of …. Note that C1 and 5 are equal and of the same value. The case shows scratches and slight corrosion. of the roller inductor can be associated with ham with homebrew ambitions, simplifica-. The maintenance factor aside, "hot-tuning" roller-inductors is a serious …. For 40 meters i pulled out an old roller inductor connected a 200pf cap across it …. A "choke" is the common name given to an inductor that is used as a power supply filter element. This homebrew transmatch is similar to the design of the famous Murch Ultimate Transmatch, which is the basis for nearly all commercial transmatches in production today. MFJ-962D is new and improved! MFJs AirCore Roller Inductor. The simplest radio receiver, known as a Crystal Set, consists of nothing more than a coil, tuning capacitor, diode detector, and a pair of …. A single gear pair design required the large gear to be almost. No stepper motors or expensive roller inductors. (This is an adapted version of an article that I wrote for the …. The red arrows show three sliding mechanical contacts in series in this design. The main thing, say for 15-10 meters, you need to make sure the coil will carry the current. The tuner in the picture on the left is a home brew unit for operation on 160 meters. I should really make a drawing ;-) -- Gregg t3h g33k "Ratings are for transistorstubes have guidelines" http://geek. 5mH or so, I consider using transformer I …. MFJ-989C 3 KW Roller Inductor Antenna Tuner Dummy Load C MY OTHER HAM RADIO - $303. Just another example of the quality put into these rigs. I wouldn't try to insert a swich. The tab will touch the end of the roller you made the complete circle of wire. Purchase by local factionalism and he retired. The heart of the S-Match is the special matching transformer in the center of the picture. Here are some links to pictures of my homebrew tuner using used components from various sources, with the exception of the gold plated roller inductor which was specially ordered from Rockwell in the USA. Palstar AT1500, roller inductor antenna tuner. I'm using this tuner with a Yaesu FRG-100. The inductor coil was home made from #14 house wire. infinia said: For inductors larger than 1. 5 gallon inductor tank that already had a screw on lid and also a 1. Introduction The MFJ-962D is a "T" network roller inductor tuner with built-in antenna switching, RF power and SWR metering and a 1:1 balun. Make: 7 “As we benefit from the inventions of others, we should be glad to share our …. The voltage amplitude of the… The voltage amplitude of the… A: Given Resistance of the …. It has very good efficiency (very low loss) but it is a bit tricky to implement - both mechanically and electrically. My calibrated eyeball says 500 pf each but I can't ID the roller inductor or see much of the interior. The roller inductor apart from being bulky often has to be rotated many times to set for band change. To construct, implement, or instigate something that goes on to become much more onerous or unwieldy than one desires or can …. Virtually all the T-network tuners I saw used roller inductors, with continuously variable inductance. Homebrew Lager Recipes Homebrew Ale Recipes Homebrew Sours & Wilds Recipes Specialty, Fruit, Historical, Other Recipes Mead Recipes Wine Recipes Cider Recipes. Z-Match 100 and mini Z-Match - This is a antenna tuner with wide range tuning for antennas with a Z of + 50 Ohms on all the HF …. Inductors find numerous applications in electronic and power systems. Bluetooth Control With a Web …. I will publish the results of my experimental tuner on …. We know coil is very important in mutual induction. Tunes 80-10m and costs in the $150 neighborhood in good condition. * QST 2014 ARTICLES * December 2014 75/50/25 December 1939, December 1964, December 1989 W1AB 102 BOOK: …. thickness 2,5mm: Dimensions: 80 x 110 x 200mm: Induction: 32 uH: Extra info: New / axle diameter: 6mm / matching handle knob (black) 40/60 mm : Eur. Manage Google autocomplete predictions. Dual roller inductor for antenna tuner or amplifier. Operates from 9 to 12 [V] DC supply. General construction reminds one of a homebrew project--useable but. Anyway, the typical impedance at the end of half a wave is around 2500 – 3500 Ohms. The roller inductor looks like a fairly-common, moderate-power, mid-sized RCA (you may be able to find a notation "RCA" somewhere in the middle of either the front or rear ceramic plate) and 24 uH. Sturdy stainless steel and fibreglass construction, can be …. A 20pF capacitor was inserted from the top of the …. AMPHF - Amplifier Parts: Roller inductor, Caps 2ea Eimac VVC 60-20 Vacuum Variable Capacitors $80. I used those big-ass round insulated ceramic shaft couplers that on one side are 3/8-inch I. The tuner was built so that the roller inductors would use one gear assy/crank handle to turn the inductors together. 5 15kv-250pF Variable Vacuum Capacitor VM Type HV. Using a toroid inductor and some small poly-film variable capacitors, the Z-match can be built into a very compact package. The pictures show a homebrew 30M add-on and SWR charts for 6M, 30M, 40M and 80M. I use an old EF Johnson edge wound roller inductor in my home brew 3cx1200 amp. SD Mines thrower Olivia Jurrens's life with diabetes and …. Kicker is no confirmation on that! Every boat can leave it there. 's a new old stock variable rotary inductor by Barker and Williamson -- this can be used in the output circuit of your amateur radio transmiter or in an …. FA: Homebrew Roller Inductor Antenna Tuner. Tube socket is from a Continental 317C. Homebrew Roller Inductor Antenna Tuner Ten Tec. Took me decades to realize that a roller inductor in an antenna tuner has many . A newly-designed, smaller roller inductor allows the AT2K to tune 6 Meters, while a relay-switched toroid adds the extra inductance needed for 160 Meter …. Addition of a small LC tuner at the base (homebrew, variable cap + recycled roller inductor?) might save you some time during setup and. In the two units shown, the 3"1n-Line RF Power 1969 QST. Remotely turn antenna switches to select which antenna feedline to bring into …. I tried pricing out building my own QRO tuner for a full-wave loop a few months ago, and got discouraged. Goldwood GW-1244 12" Butyl Surround Woofer 4 Ohm. (The plate cap from a SB-220 Amp) and the other cap is a 350pf cap that has roughly 1/2 the plate spacing. 5 - miscellaneous fixed inductors 1 - ferrite balun core (whoopee!) 6 - rectifier diodes 3 - signal or switching diodes (appear to be …. Covers 10-160 meters with full …. Here is a demonstration video on how to use. If you’re in need of parts from top quality aviation manufacturers such as Aviall, look no further than Internet for …. The vacuum cap and roller inductor have been removed from the above tuning unit. 100W, the resistor is 150 degrees hotter than the heatsink, and with a max temp of 175C, you'd better keep that heatsink at 25C. 4uh 8 Amp Roller Inductor (NOS). Roller Inductor 26574 For Ham Radio Tuner Vintage Diy. The world's most popular 3 KW roller inductor tuner with cross-needle meter gives you the widest range matching network available for coax, balanced …. 5-1000mh ferrite core smd power 1 henry choke filter 1mh inductor 22uh. ) That roller inductor in the middle was an expensive part back in the day. If you subscribe to CQ magazine , be sure to …. A gear train coupled to a 10-turn pot was built and is shown in pictures A, B, and C. 6MHz, a model that illustrates the potential for very low …. com) My home made job is like the T-match with a roller …. Made in the USA | Add to Compare; 4021162 Wilco Choke 2. 15db on 10 metres matching roughly 500 ohms and less on the lower bands using such a setup. In the box was also a real valve/tube GDO. 0402CT Low Profile Chip Inductors. Plans for a simple Antenna Tuner. These tuners were used by the military during the Second World War. Transceiver with internal ATU may match the antenna on all of the HF bands. Caution: Roller-inductor tuners are the most troublesome of all outboard tuners. by Howie, W9NHM and is daily service on 160. Only with of 16 to 21 syllables. 3500z Homebrew Linear Amplifier: A Useful 1Kw To Play With. Antenna loading coil: Everything You Need t…. The MAC 200 ATU is designed to cover 1. A variable capacitor for the input. Homebrew Your Own Inductors! Can't find the inductors you need for an antenna, a tuner or amplifier? Build your own—it's easy!. Both are unbalanced tuners, using a balun to feed open wire. I thought the members of this forum would like to see a tuner I built to take advantage of the longwave capabilities of my receiver. Matching everything would work! +1-611-548-1173. D&D Beyond Character Sheet. You may have to do some rebuilding, like upgrading the switches to silver-plated leaf, but that's a good way to get into home building if your experience level is low. Conical-Inductor Tanks, Stands and Specialty Doorway Tanks $160 (Gresham) pic hide this posting restore restore this posting. So bottom line is I am OK using a roller at the 50 w level for the hi-Q 4CX-350FJ amp, (100ma X Q50 = 5A) but maybe I should stick with a …. In the past, the biggest limitation to a compact 100-watt version was the necessity of using large air-wound inductors, and the ability to find …. Tuning Roller Inductors in the later 32G shown in the operating position above. FOR SALE: Comet 5 inch magnet mount, SO-239 connection, RG-58 …. Am using a Johnson 229-203 roller inductor 20 µH/5 A, a Jackson Brother 2 × 300 pF/1 kV variable capacitor and on 80 meters I add two 180 pF/2 kV …. Of course for simple open-air designs, a wire and alligator clip will suffice. Foam Roller Accessories Foam Roller Storage Bags Foam Rollers Hand Exercisers Inversion Tables & Systems Medicine Balls Power Towers Push-Up …. Just in case anyone in the UK is thinking of building one and looks at this page, I built one with the Falon AC100 (11mA) and an "INDUCTOR AIR-CORE …. A small-sized roller inductor operates all the way up to 6 m, while a relay-switched add-on inductor allows 160 m operation. W9IE's homebrew control box Inside the control box The roller inductor Remote motor adjuster Turns counter photo interrupter KARS MEMBERS TO OPERATE INQP In a fitting tribute to Howard AK9F, K9NR, K9CS and W9IE will be operating the Indiana QSO Party on May 5th from Perry County, Indiana at Howard's farm near the Ohio River. The values arn't that critical you can fudge a little. FA 2KW ANTENNA TUNER WITH ROLLER INDUCTOR. The mechanical and electronics for the robot has been mostly completed and we are currently writing the software for it. The waveform in Figure 3b shows inductor current …. Crystal pulling is Not being promoted here as a commercially viable method. 075" plate spacing, a triple ganged air variable with the same plate spacing at 220pf per section (only two sections of the stator will be used), a couple of appropriate ceramic switches, and the assorted small hardware necessary. Lemingge T50-26 DR shield inductor coil 3a 10uh 22uh 150uh 330uh smd power homebrew roller tunable inductor. An initial “breadboard” matching circuit experiment: A 28 microhenry roller inductor, 365 pf air variable and an additional 100 pf …. antenna has a small roller Inductor monted on the bottom of a tripod with a telescoptic pole and a 1m telescptic car radio antenna on top. However, don't overlook the merit of …. T-Network = capacitance 10-800 pF (Q=3000), inductance 30 µ H (Q=200). As an example, suppose you wish to operate the wire at 14,250 KHz (14. Homebrew Your Own Inductors!. Motorised roller inductor from Marconi AD307 HF …. Using the amplifier's frame to bend the aluminum plenum. antenna for 80m – 10m ($115) a 140-ft. Most antenna tuners have an inductance rotary switch and two capacitors. First of all, this SWR meter in this article is not exactly homebrew, as I based the circuit on the schematic in the excellent book Arduino Projects of Amateur …. (Although I suppose it could have been a commercial unit and somebody stripped the paint off the case. Hoping to get the chassis all cleaned up and the roller inductor functional again. G3YNH info: Variable inductors used in HF antenna matching n…. The MP line of camouflaged manpack antennas are. Note the use of the flat conductor in the roller inductor. It is rated at full US legal power, and features a roller inductor, …. Based on the Choke Inductor market development …. May 20, 2021 Thomas Witherspoon 5 Comments. Hp proliant dl380 g5 install windows 2016 Hp proliant dl380 g5. Then, to make matters even worse, Albert informed me these were the "Standard" model, and a "Signature" model and interconnects would follow. sole agent for Centre And Clinton …. I know it looks "Homebrew" but Mr. 00 shipping Dentron AT-160-10 AT 3KW Ham Radio Antenna Tuner Untested $249. The throttles are opening all the way though, I could see that when I had the cover and the air inductor off. Roller Inductor series resonance: The sweep below, taken on an 8753C vector network analyzer, shows roller to chassis terminal impedance from a floating roller's frame. REMOTE CONTROLED ROLLER INDUCTOR It is not too difficult to put a motor on a roller inductor and turn it W9IE's homebrew control box. 29-4-2017: The antenna tuner is something you can do yourself, variable capacitors, roller inductor and knobs are all used components and they come from the Rosmalen radiomarket. MFJ replacement air roller inductors used in the antenna tuner model MFJ 986 and have an inductance of 44 …. Notice the feed line is shown tied (shorted) together at the tuner. TEXAS STAR DX-350HDV 2879 transistors $345. You now have a voice coil actuator. However at the Lew McCoy's transmatch is used a roller inductor and all capacitors are variable ones. Clone via HTTPS Clone with Git or checkout with SVN using the repository’s web address. Adding the helper woofer doesn't do anything to the main woofer response in the lowpass region (the top end of woofer response,) the reason …. CX Daily: China Turns to Credit Easing to Kick-Start Sluggish Economy. The principal is quite simple but im not super mechanically . The motor drives on the 2 capacitors are from Samsung ice makers, and the roller inductor drive is the loading drive from a Panasonic VCR. MFJ-962D is new and improved! New features include MFJs AirCore Roller Inductor, new aluminum-skirted knob set including a weighted deluxe spinner knob, ultra compact. This is just more of a cool and pretty project than anything else and the rolling inductors ive seen for sale are alot they make 400pf air caps cheap. With the ability to handle up to 2000W ICAS …. Seller: musickman1979 ️ (1,042) 100%, Location: Eldridge, Iowa, US, Ships to: US & many other countries, Item: 224681906423 Vintage Barker & …. The original main roller inductor's mounting plates were much too high so new brackets were made to bring the inductor height down. In fairness, I did not like the appearance of several solder joints and re-worked them. Joined Dec 25, 2008 Messages 4,023 Location New Zealand. Rather using print roller I decided to move the bed from a stepper motor. In the version shown here, I used a tapped inductor (instead of a roller inductor) to facilitate rapid bandswitching. Dual climate rubber outsole is surprisingly …. my homebrew magloop cost me under a fifth of cost of the Alexloop) but I guess in the end …. 102-752 RF Choke, 5 pi windings. Further perspective on the variations of the 32G throughout production can be …. Dimensions are dependent on the size of the coil (see Table 1). I did tape the base pipe to the coupling …. 2mm (Pm = 100-500W) high-strength enameled wire is wound on a 25mm diameter skeleton. Either cap can be tuned close to series resonance with the coil and generate some colossal voltages at the top of the inductor. The L-match is the simplest way to transform the widely varying impedance presented by a wire antenna to the 50 ohms required by the transceiver. Roller Inductor series resonance: The sweep below, taken on an 8753C vector network analyzer, shows roller to chassis terminal impedance from a floating …. I have had no trouble with it whatsoever. This dip may be barely noticeable. The inductor sliding shaft and contacts will likely get slightly hot if it were feeding my wire; I have to have a blower on my own tuner's roller inductor's contacts …. To the lower left, a closer look at the supply system of DC to the anode with the DC supply inductor. A E Adams Limited United Kingdom A E Adams Limited specializes in providing contract packing service manufacturing both branded and own label products …. With this in mind I decided to build a new ATU that would cover 160m and also handle much more power. 책《Keep Sharp》 CNN 의학전문기자, 미국 신경외과 의사 산제이 굽타는 지난해 출간해 아마존 건강 분야 1위를 차지한 이 책에서, 그는 “뇌는 나이나 경제적 능력에 상관 없이 평생 꾸준히 지속적으로 향상시킬 수 있다”고 …. Primarily developed to be used with HRI-33 roller inductor, since the shaft design makes possible to connect the encoder to the roller inductor through an …. Yes that is a roller inductor on the right. 5KW PEP HF TUNER ROLLER INDUCTOR. Oem 84 89 Toyota 4runner Truck Hilux Heater Ac Blower Motor. The thru hole part kludged onto smd pads will put a lot of stress on those pads and the solder. Tuning with the SPC transmatch: More difficult, because of the narrow bandwidths. Homebrew Your Own Inductors! Can’t find the inductors you need for an antenna, a tuner or amplifier? Build your own—it’s easy! By Robert H. Please choose from the following CHOKE / INDUCTOR Sub-Catagory choices: COILED. Being a parallel resonant circuit, the Z-match can provide some band-pass filtering for …. The L in the circuit can't be a roller inductor or a tapped one. GR-DVP7 camcorder is in the shop with a broken inductor, JVC part #NQLZ010-390X. A support frame was made with strips of plastic. I was wondering where did you connect your AIO pump. You can add a powerhouse linear amplifier at no additional cost. Yes, my HF2V is a HF4V now! There's also the idea of replacing or augmenting the 80M coil with a motorized roller inductor. 8-25 days by regular post for Worldwide, 119mm O/D 304 Stainless Steel Sanitary 4' Tri Clamp Ferrule …. Yours appears to be this one, and, as of this writing, it appears …. A conservative RF current estimate would be E/Z=I where E is DC plate voltage and Z is choke impedance. A homebrew loop will require a lot of maintenance and cost a lot of money (at least. Woolen Bloom Mock Neck Sweater for Women Oversized …. 102-752 RF Choke, 5 pi windings, 850uh, 500 ma, MFR: E. RF from homebrew open wire feedline. TYPE: T MATCH, ROLLER INDUCTOR, AIR GAP CAPACITOR. The connector to the anode is home made. Home Brew HF Vertical Will cover 80M to 20M HF bands antenna has a small roller Inductor monted on the bottom of a tripod with a telescoptic pole and a 1m telescptic car radio antenna on top. The two roller inductors must be tuned simultaneously, and a means must be found to switch the variable capacitor from the input side to the output side. Figure 3—Drawing of a typical coil-winding form and its insert. But if I use the simulator's controls to manually adjust the …. For the SPC or Ultimate Match you will need 3 components: 1ea 180pf single section variable cap, 1ea roller inductor or tapped inductor at 28 uh or 30 turns #16 wire space wound to cover about 4 inches with 2" dia, 1 ea dual section variable cap at 180 pf per section. goto homebrew AM BROADCAST BAND micro-power transmitter goto homebrew 40 meter CW receiver project based on 7. So, although QST cannot review it, these models make sense, and have the ability to be used effectively …. BASE STATION ANTENNAS HAM.