Output

The internal 22 Hz zero-bias keying signal from the output of IC6 is connected to switch S2. S2 selects either the internal or external keying signal and. applies it to the keying logic input. Referring lo Fig. 3, the internal keying signal has the same effect as alternately opening and grounding the keying input. When the internal keying signal is at or near zero volts, the keying input grounded columns apply. When the internal keying signal is at or near minus 3.6 vdc, the keying input open...

Letters

The article on Adjusting FM Deviation11 in the June 73 was interesting, but it does have some drawbacks. The author recommends monitoring the receiver with a scope while adjusting the transmitter deviation and watching for a flattening out of the CRT display. The trouble with this approach is that the flattening out is not necessarily an indication of the receiver band-pass limit it could just as well be audio limiting of the deviated transmit signal* A better approach If the system contains...

Transistor Dc Supply

This power supply will operate transistor radios and other devices under repair or where batteries are a drag to replace. Voltage range 0-20 vdc continuously variable. Meter ranges 0-20 vdc, 0-20 mA, 0-200 mA, Maximum current capacity 150 mA 20 v or 200 mA 10 v. Pilot lamp. AC ripple less than .25 mv rms( Fused, Has built in power transformer and 30 watt power transistor. Built for continuous duty. Ralph W. CampbeiJ. W4KAE 316 Mariemoni Drive, Lexington, Kentucky A 23 element yagi was defeated...

Mgz

Relative phase and gain of 18 element quad. The elements were glued to the boom with epoxy, but it was first necessary to coat the rounded No. 6 hard copper with a thin layer of epoxy diluted with a very small amount of rubbing alcohol. Of course, the epoxy must be pre-mixed and the alcohol should not contain any glycerine. Prior to this, the element surface should be clean and dry and roughed-up with cabinet paper. After all 17 loops are coated, allow two days for the undercoat to dry....

FM Repeater

For those who don't have a two meter FM receiver and want to listen to the repeater (if you have one in your area) this little converter will do a very good job into an AM radio. You will recognize this converter as being similar to police converters. (In fact, changing the crystal and repeating the antenna coil should put a police converter in the ham band). The unit is built on a printed board 2-1 8 by 2-5 8 inches. Ti e capacitors are all from my junk box and include small round lubular,...

Bti Amateur Division

Built to Operate Dependably With Plenty of Reserve For heavy duty applications such as MARS, high power RTTY and SSB. Price 89500 The usual procedure ror determining the rf capabilities of unmarked transistors involves plugging the units into a standard oscillator circuit and then playing with circuit values until oscillations start or the experimenters patience gives out. Fortunately, there are simpler and more accurate methods of judging a transistor's capabilities, i his article will be...

Prestel Field Strength Meter

A Gold-Mi ne for Antenna Installers Frequency Range 40 to 230 and 470 to 860 Megahertz. Calibrated oufword from 10 to 50,000 Microvolts. Nothinq ma kes it easier to properly and speedily fin d ts e correct place to Install TYf FM and Communication Antennas, You can measure and hear the signals with this 4' volt battery economically powered un t, There is nothing else like i+l 548 Broadway, New York, New York 10012, Phone 212-925-6000

Vol

Alternate Outpyi circuit for more gain. the basic receiver (Fig. 2), The intention was to use it as a utility amplifier around the shack as well as with the basic receiver when loud speaker operation was desired. Almost all of the parts, including transformers, transistors and speaker, were taken directly from the smashed broadcast receiver. The one noteworthy addition is the volume control, and that is a W60SA original as far as 1 know.* It had to be put where it is instead of in the...

Antennas

Which uriL llYCiUAR ANT E YOU will GET OUr BETTER. New book gtves st p by step nstruc tions ( 1 76 pages, over 200 (lustrations) for making all stand ard types I long wires, dtpoles, yagiv trap, etc J plu* MANY rtoi itscribed elsewhere tov. -ost Timiaiure beani* from converted TV antennas INDOOR BEAMS, invisible an tenn js 40 METER D> vertical b ams NOVlCt BAND DX many MANY others SEC RE TS o* r j ne up ior MORE OUTPUT HOkv to hooV uv ami -js* ANTENNA TEST GEAR Buy frook Harr Anlennii...

T

GvtnwiVi 1S4 G G, 143 Global,' 123 G'iodhc rt, 151 Gn-cne, H titrOin, 31 HAL Devices. 82 Hdt'ry. I 5 HCJ. 119 Heathkit Electronics II Henry, 141 HAL, 91 I nsi.im Gourmet, 37 Ini f national Cr yttai. 3 Jan CrystaL 149 Jeti- ionics. 156 Jennings 63 MvQsrf, 123 M shna 157 M sley. 35 Murch. 29 Rentrante , 93 Park, 75 P tronij x , 01 P i kenng, Hl PolyPaki. 159 PrQductoi 'onli 1 19 Ratfio Shop, 1 19 RedHne. 1143 H hn, 25 Sulch. 77 Sams. 6 Security 127 Short Wave Ouide, 82 Slop. 156 Vjnguafd. 33 47S1...

Compressorpre

30i db compression range Low-noise FET input stage m 5-transistor and 1-diode circuit Adjustable input and output levels Printed circuit construction with easy-to-follow instructions 3-way jacks for PIT operation Easily installed in mike line Other Kits Audio Amplifiers Power Supplies Test Equipment Treasure Locators and many others FREE Date sheets with circuit description, diagram t and specifications for aft kits P.O. Box 327 Upland, California 91766 Phone 714-965-1540 The brass eyelets are...

Hisensitivity Uhf Receiver

Stoddart RFI Meter NM-50A with pwr. sply, cords, dipole holder, 3 pair dr-poles. Input 50 ohms. IF 60 mhz. Band width I mhz at 370 and I 8 at I ghz RF. Image amp spurious-response reject better than 40 db. Sensit. as a 2-terminal tuned voltmeter is 10 uv will be less with l-pair dipole, but you can make an array to bring it up. If the voltage-attenuation calib. charts didn't get lost it would be worth 1,250 in surplus, 2,852 from the factory so we will seM it as a simpie receiver...

Info

I have seen this done many times, even with the crystals ordered over a year apart. The dual channel unit is simplicity in itself. Closing the switch actuates the movable arm of the relay. These arms are connected to the original wires going to the crystal socket With the relay inserted, the additional inductance and capacitance may necessitate a small adjustment of the oscillator padder However, if correlated crystals are in u eT the adjustment should be the same for both channels. On the four...

Swan Cygnet

Oscillator component board, Mark 2125 khz on left. Oscillator component board, Mark 2125 khz on left. The majority of the circuitry is assembled on three 3 x homemade component boards. The mark and space oscillators are contained on one of the boards CB1 , the gated amplifiers and lamp drivers on another CB2 and the power distribution and keying circuits on the third CB3 . The complete RTTY Tone Generator is shown schematically in Fig. 2. The mark and space oscillators are conventional LC...

Peterborough Nh

Robert Bailey K3aqh

5gry w5zbc double dipole or skelton cone use 2 ivire or larger 2 . DB 80 METERS 5 to 6db 40-iqmeters ovefl dtpote LADDER L NE TO ANT TJNER V KING MATCH BOX WITH s R TO EQUIPMENT TUNES 80-10 METERS I I SWR LADDER L NE TO ANT TJNER V KING MATCH BOX WITH s R TO EQUIPMENT TUNES 80-10 METERS I I SWR 5gry w5zbc double dipole or skelton cone use 2 ivire or larger 2 . DB 80 METERS 5 to 6db 40-iqmeters ovefl dtpote Robert H, Grenell, ex-W8RHR 3926 Beech Street Cincinnati, Ohio 45227 No government has...

Unique RF Plate Choke

At times it is difficult to obtain the exact rf plate choke that one may desire for a new final amplifer. In looking for a material to make a 2 ampere 5000 volt dc rf plate choke for non-ham use, I came across a material made by DuPont called Delrin. Delrin has high strength but can easily be cut and drilled. It has excellent electrical properties as an insulator with a high heat distortion temperature. These features make it an excellent form for rf plate...

Arnold S Engraving

Get on 6, 2 and 1 meters with our high gain low noise transistor converters. All popular I F's available. Built in power source. Units shipped prepaid when check or money order accompanies order. Order yours toda . Get on 6, 2 and 1 meters with our high gain low noise transistor converters. All popular I F's available. Built in power source. Units shipped prepaid when check or money order accompanies order. Order yours toda . through K4. the PUT iurns on, and the anode and gate voltages fall to...

Kioxk

Most experimental circuits are tried out bread-board fashion. Hand capaci y effects can be troublesome, especially at the higher frequencies, in order to minimize hand capacity effects the following gadgetry was devised. The adjustment screws in trimmer capacitors and slug-tuned rf coils is fitted with a flat piece of tin, securely soldered into the slot. Then it may be adjusted with a long hollow tube of plastic or hard rubber which has been slotted at one end for this purpose. This idea may...

Tj H

Fig 2, Circuit which evolved from an otd-two-tube blooper from 1932. Fig 2, Circuit which evolved from an otd-two-tube blooper from 1932. band out of business. Not only that, but the receiver will radiate a pretty healthy signal itself, which can be heard for three or four biocks. What is its claim to fame Well, it is a good projeel for the beginner in radio or transistors or FET's. It could also be fun on a pack trip into the wilds where P. G. amp E. has not yet penetrated with its handy 60 hz...

Kpur

Remain off until the transistor to be tested is inserted and the controls are set as above. Alter setting the function switch on the polarity of the transistor to be tested, inserting the transistor into the test socket, ai d adjusting the controls as outlined above, power may be applied. The VCE IC and IB controls are interactive that is, changing the selling of one will affect the meter reading controlled by the other. Therefore, it is possible to obtain a dc curve within the limits of the...

All Band Trap Antenna

Ktd ces Intftirrcii.f ind Wiftor ALL Amateur Transmitters. Worfe, VGuaraoteed for 10M gt Wam Pow Re.ep Hin ranger. Compltie er Light. Neat, Weatherproof. 9b i'. 1 ohm retdUne. Scatrd ftiirrun ftipi For novicr ind tJI cli r d ia imiteun1 Himin t - gt 5 sepau r nTeni 1 il11 ttllfr pcrformince guarjnrcfd BCMiKO-li 10 mettr tamis Compile 102 f lt Sl S. JOOO E MO metet hindi, SJ ft thest for w rlJ shqrt r ception SlS- Send nnlv 3 00 icish, .li, mo and p y pOitnun balance i uD plus pmta e on anivaJ...

Antenna Mart

Rapidly, and we have achieved two-point tracking. We can now replace the fixed capacitors and tuning switch, if we like, with a 3-gang variable capacitor. We have two-point tracking, which means that everything is all right at our I wo tracking frequencies but hat some error exists at all other frequencies. If our tuning is to be only over a narrow range with respect to frequency, such as the 1 dif ference between band limits of the IOmeter band, two-point tracking will suffice. The error will...

Magnetic Memory Drum

Memory Drum Hughes Aircraft

This memory drum originally cost the government over 56,400.00, and is a truly fantastic piece of equipment. It was made by Hughes Aircraft Co. as part of an aircraft computer. The unit is completely sealed and therefore the drum surface is in excellent condition. It has 146 heads mounted in 11 columns, 12 are phase adjustable timing heads, the drive motor requires 115 VAC 400 cycle Hz 150 VA, and has a speed of 800 RPM. SH. WT. 50 . MMD-59. 100.00

An FET Regenerative

It appears that almost anything which a bi-polar transistor can do, an FET can do better The simple regenerative 3.5 to 6.0 mhz receiver described here is another case in point. Three or four months ago 1 started out to build an SWL receiver for my ten year old son. i used the circuit shown in Fig. 1 which is similar to that in the December, 1966, issue of 73 Magazine. There were two problems with it which I could not seem to overcome. The regeneration control was too critical, or at least I...

Of Unmarked Crystals

Surplus, unmarked crystals are easy to obtain, hut are of little value to most experimenters since ilie frequencies arc unknown. By using a Grid-Dip-Oscillator and or a surplus frequency meter, the frequencies of the unmarked crystals may be determined to an accuracy exceeding 1 depending on which instrument is used- Measurement with Grid-Dip-Oscillatoi 4 OR 5 tURNS NO. iG OR SMALLER wound around G DO COIL Fig 1 Setup for rough frequency determination. Fig. 1.shows the setup for using a...

One Million Dollars

Your amateur station will look like a million dollars with one of these beautiful 18 diameter world illuminated globes sitting on the desk. Besides dressing up the hamshack, one of these globes makes pointing your beam a cinch. No map can give you the feel of the world that you et with a globe- If you are going to get a globe you might as well get a good one. This Hammond tflobe sells in the stores for 25 and is a bargain at that price. Through some finagling we can let you have one of these...

Ax

Diagram Meter

The driving voltage is tapped down on the driver tank coil to provide a proper match. It was found, experimentally, that a point turn from the ground end of L3 provided the proper amount of drive. The audio section uses a 12A X 7A and offers a good match to most of the handheld crystal or ceramic microphones. I used choke modulation because 1 later plan to build a small companion receiver. By using an audio output transformer for the modulation choke, the audio section of the transmitter will...