Home-made HF receivers (shortwave) are manufactured on the basis of resistor switches. Many modifications include a wired adapter and are equipped with amplifiers. The standard circuit has high frequency stabilizers. To adjust the channels, knobs are used.
It should also be noted that the receivers differ in the conductivity and frequency of the tetrodes. In order to understand this issue in detail, it is necessary to consider the schemes of the most popular receivers.
Low frequency devices
The circuit of a home-made HF receiver of a low frequency includes a controlled modulator, as well as a set of capacitors. Resistors for the device are selected at 4 pF. Many models have contact triodes that operate on converters. It should also be noted that the receiver circuit includes only single-pole transceivers.
To adjust the channels, the controls are used, which are installed at the beginning of the circuit. Some models are made with only one adapter, and the connector for them is selected linear type. If we consider simple models, then they use a grid amplifier. It operates at a frequency of 400 MHz. Insulators are installed behind the modulators.
High Frequency Tube Models
Homemade high frequency HF tube receivers include contact converters and low conductivity sensors. Some experts speak positively about these devices. First of all, they note the possibility of connecting transceivers. Triggers for modifications are suitable for the controller type. The most common devices with semiconductor resistors.
If we consider the standard circuit, then the comparator is of an adjustable type. Output resistors are installed with a capacitance of at least 3.4 pF. Conductivity does not fall below 5 microns. Regulators are installed on three or four channels. Most receivers use only one phase filter.
Impulse Modifications
The home-made pulsed HF receiver in the amateur bands is capable of operating at a frequency of 300 MHz. Most models stack with contact stabilizers. In some cases, transceivers are used. The increase in sensitivity depends on the conductivity of the resistors. The capacitance at the output is 3 pF.
Contactor conductivity averages 6 microns. Most receivers are manufactured with dipole adapters, for which PP connectors are suitable. Very often there are capacitor units that operate on thyristors. If we consider models on lamps, it is important to note that they use single-junction comparators. They turn on only at a frequency of 300 MHz. It must also be said that there are models with triodes.
Single pole devices
It is easy to configure exactly unipolar home-made tube HF receivers. Do-it-yourself model is assembled with variable comparators. Most modifications are designed with low conductivity stabilizers. The standard receiver circuit involves the use of dipole resistors, in which the output capacitance is 4.5 pF. Conductivity in this case can reach up to 50 microns.
If you assemble the modification yourself, then the comparator must be prepared with a transceiver. Resistors are soldered to the modulator. The resistance of the elements, as a rule, does not exceed 45 Ohms, however, there are exceptions. If we talk about receivers on relays, then they use adjustable triodes. These elements work from the modulator, and they differ in sensitivity.
Assembly of multi-pole receivers
What are the advantages of a multi-pole HF detector in the amateur bands? If you believe the reviews of experts, these devices give out a high frequency and at the same time consume little electricity. Most modifications are assembled with dipole contactors, and the adapters are wired. Connectors for devices fit different classes.
Some models include phase filters that reduce the risk of wave interference failure. It should also be noted that the standard receiver circuit involves the use of a regulator to adjust the frequency. Comparators for some instances have a channel type. In this case, the triode is used with only one insulator, and its conductivity does not fall below 45 microns. If we consider receivers on expanders, then they are able to work only at low frequencies.
Dual Junction Models
Amateur HF receivers with dual junction converters are capable of stably maintaining a frequency of 400 MHz. Many models use a pole zener diode. It is powered by a converter and has high conductivity. The standard modification circuit includes a three-output controller and a capacitor. The amplifier for the model is suitable with a varicap.
It should also be noted that high-frequency devices with this type of converter can perfectly cope with impulse noise from the unit. Comparators are used with grid and capacitive resistors. The resistance parameter at the input of the circuit is about 45 ohms. In this case, the sensitivity of the receivers can vary greatly.
Three-wire devices
The home-made HF receiver for amateur bands with a three-wire converter has one contactor. The connectors are used with or without lining. It should also be noted that resistors are used with different conductivity. At the beginning of the chain there is an element of 3 microns. As a rule, it is used in a single-pole type and transmits current in only one direction. The capacitor behind it is located with a linear conductor.
It should also be noted that the resistors at the output of the circuit have a low conductivity. In many receivers they are used of variable type and are capable of passing current in both directions. If we consider modifications at 340 MHz, then in them you can find comparators with grid triodes. They work with increased resistance, and the voltage is as much as 24 V.
200 MHz modifications
A homemade HF receiver in the amateur bands with a frequency of 200 MHz is very common. First of all, it should be noted that the models are not able to work on comparators. Linear modifications are common. However, the most common devices are considered models with transitional decoders. They are installed with a set of adapters. The resistors at the beginning of the circuit are used with high capacity, and their resistance is at least 55 ohms.
Amplifiers are found with filters and without them. If we consider switched modifications, then they use duplex capacitors. In this case, the stabilizer is used with the regulator. A channel modulator is required to tune channels. Some receivers work with receivers. They have a PP series connector.
300 MHz devices
A homemade HF receiver for amateur bands with a frequency of 300 MHz includes two pairs of resistors. Model comparators are found to have a conductivity of 40 microns. Some modifications contain wire extenders. These elements are able to significantly remove the load from the capacitors.
If you believe the reviews of specialists, then models of this type are distinguished by increased sensitivity. Home-made devices are made without tetrodes. To improve the conductivity of the signal, only transistors are used. It should also be noted that there are devices with channel filters.
Modifications at 400 MHz
The 400 MHz device scheme involves the use of a dipole adapter and a network of resistors. The transceiver in the model is used with an open filter. To assemble the device with your own hands, the tetrode is first prepared. Capacitors for it are selected by low conductivity and sensitivity at the level of 5 mV. It should also be noted that receivers with low-frequency converters are considered common devices. Next, to assemble the device with your own hands, one modulator is taken. This element is installed before the converter.
Low sensitivity tube devices
The HF tube receiver for amateur ranges of low sensitivity is able to work on different channels. The standard scheme of the device involves the use of a single stabilizer. In this case, the adapter is used open type. The conductivity of the resistor should be at least 55 microns. It is also important to note that the receivers are made with plates. To assemble the device with your own hands, a set of capacitors is prepared. Their capacitance must be at least 45 pF. It is especially important to note that receivers of this type are distinguished by the presence of duplex adapters.
High Sensitivity Receivers
The high-sensitivity device operates at a frequency of 300 MHz. If we consider a simple model, then it is assembled on the basis of a comparator with conductivity from 4 microns. At the same time, filters under it are allowed to be used with a lining.
The transistors on the receiver are installed single-junction type, and the filters are used at 4 pF. Wired transceivers are quite common. They have good conductivity and do not require large energy consumption.
The modulator may only be used with one varicap. Thus, the model is able to work on different channels. To solve problems with negative resistance, an expansion capacitor is used.