Circuit Schematic learn

Wave antenna 5/8 consists of a vertical radiator which is fed at the base of the antenna. A suitable device of some sort should be added between the antenna and feedline if you want to eat with coax. Adding a coil in series with the antenna on the base is one of these methods are suitable. 

So why would anyone use an antenna 5/8 wave if they have to go through all that extra work? After all, a ground plane antenna provides a good match. There are several answers. The first is GAIN. The computer shows that the antenna (mounted 1 foot above the ground) has a margin of about 1.5 dBd higher than a dipole (also installed 1 foot above the ground.)The second reason you might want to use the wave 5/8 vertical is to get a lower angle of radiation. Peak radiation angle A half-wave antenna is 20 degrees. You will find that the angle 5/8 wave antenna radiation is only 16 degrees so it is better dx antenna. 

 You may have noticed a pattern developing here. A quarter-wave ground plane antenna has a radiation pattern that produces the maximum gain at about 25 degrees and half-wave antenna drops to 20-degree angle, and wave antenna 5/8 further drops to 16 degrees angle. So why not just keep extending the antenna to one full wave? Well it would be nice if it worked, but unfortunately the wave patterns begin to create a very high angle of radiation waves exceed 5/8. So weve reached the maximum gain at this point and extend the antenna further reduce profits only where we want it (low angle). 

Of course if you are interested in a very short jump, extend the antenna will produce a nice profit on the dipole.All the length of the antenna depends on various factors. Some of these factors are: height above ground, the diameter of the wire, nearby structures, the effects of other antennas in the area and even the conductivity of the soil.This page allows you to calculate the wavelength for the antenna 5/8. It uses the standard formula, 585 / f (178.308 / f for metric) MHz to calculate the length of the element. If you have experimented with 5/8 wave antenna before and know a better formula for your QTH, feel free to change the formula accordingly. This formula is for the antenna wire. 

Of course if you build your antenna out of the tube, total length of the antenna will be shorter, for example I have found that 21.5 feet seems to provide maximum benefit to the frequency of 28.5 MHz when using a 1 "tube, and 22.5. Foot seems be the best long-wire at the same frequency. Since the formula to calculate the antenna to be about 2 feet shorter, be sure to experiment and maybe add a little for your final term.

A drawback of low frequency oscillators using bipolar transistors or TTL logic is that the timing capacitor usually has to be a high value electrolytic.
Using a field effect transistor at the input of a schmitt trigger, means a low value capacitor can be employed . The trigger by Q1 and O2 has a hysteresis of approximately 3V. This is controlled by the 3V zenen Mth C1 uncharged O1 is off and O2 is forward biased. The voltage at the source of Q1 is approximately +4V. O2 conducts, thus turning on TR3. The output is therefore at +1OV. C1 then charges via R1 and the gate voltage of Q1 goes positive. When the gate voltage is sufficiently positive Q1 conducts, turning off Q2. The positive feedback from the emitter of (12 to the source of (11 ensures a rapid switch off. Q3 also  switches off and the output goes to -5V. Capacitor C1 now discharge towards -5V, but when the voltage across C1 falls by approximately 3V, Ol ceases to conduct, turning on 0.2. The collector load of Q3 is connected to a negative supply giving a  50% duty cycle. (The circuit still oscillates if R7 is connected to GV but the duty cycle will change, the output remaining at OV for a longer period than at +10V). With the components as shown the frequency of the output is approximately 0.025Hz. 



 The multiple amplifiers in the LM3900N device are very suitable for use ln waveform generators at frequencies of up to about 10 kHz. Voltage controlled oscillators (the frequency of which is dependent on an input voltage) can also be designed using the device. A simple square wave generator is shown. The capacitor Cn alternately charges and discharges between voltage limits which are set by R2, R 3 and R4. The circuit is basically of the Schmitt trigger type, the voltages at which triggering occurs being approximately Vt/3 and 2V+/ 3.



The time constant T of this circuit is equal to 0.7 R;C2. Where T is in seconds, R1 in ohms and C2 in farads. For example when R1 = 10 k and C2 = 100 microfareds the time constant will be one second. Capacitor C2 may be selected over wide a range and Ry may be a potentiometer 100 k maximum. Outputs 1_and 2 provide pulses of opposite polarity but the rise time of output 2‘is long due to the charging current of C2. 

Sensitivity and selectivity are the major concerns of a short wave enthusiast when he looks up for a receiver. Commercial communications models with superhet circuitry surely satisfy his requirements, but these are expensive. He would rather go for a homebrewed radio, being a regenerative receiver an affordable choice.

Im also a short wave listener and for some time I used my familys MW and SW tube radio, Philips brand. Then I switched to a Sony ICF-7600 with ceramic filters in the IF stages. High selectivity was attained with this radio receiver.

A Short Wave Regenerative Receiver Circuit Diagram

 I then discovered how much fun it was to build radios in my spare time, having tested a variety of designs available in books and on the web. Finally, I managed to make my own designs. One of them is shown in Fig. 1. It is a nice performer and will tune from the 22 meter international broadcasting band down to the 11 meter band.

It is best that the 100 pF variable capacitor be a vernier type. Tuning will be easier this way.

Q1 is the amplifier-detector and along with its associated circuitry forms a common collector Colpitts oscillator that not actually oscillates: it operates as a regenerative amplifier, with R9 as the reaction control. In achieving this result, the transistors input capacitance plays an important role. The oscillating mode is employed when copying CW or SSB. Otherwise, the stage should be left very near the threshold of oscillation for maximum sensitivity and selectivity.

Q2 and Q3 form a high gain audio amplifier and ample volume should be expected at the output. This is why a volume control has been included in the circuit. A high impedance crystal earphone should be used at the output.

Pictures of My Prototype:

Below a sheet of metal used as a ground system: