Universal VHF of a WC receiver (70-l50mgts)

12/18/2016 - 11:35

A few years ago before the author there was a task to create the tiny mobile single-channel receiver, capable to be reconstructed in a wide range of frequencies and to accept both broadband, and narrow-band a WC, or by switching, or, as a last resort, with the minimum alterations.

Studying of technical specifications and ex-recops with single-crystal WC receivers on the K174kha34 base and it similar, showed full insolvency of the last for application in serious designs - low sensitivity and selectivity, impossibility of regulation of a pass-band, problematical character of application external stable a heterodyne etc. Then the author saw practically all magazines "Radio" and "Radiolyubitel", for previous years, hoping to find something ready. Unfortunately, as expected, anything ready it was not possible to find. However the greatest interest was caused by designs [5,8,9]. And the most optimum the design of the following look - VCh and the converter from [9], PCh and the detector from [5], and FVCh and UNCh from [8] looked. Thus the design turned out rather gromozky.

the Following stage of search was the review of Internet sites of producers of chips. Exactly here, on a site MOTOROLA the author found [13] circuit of the receiver which actually included all ideas of the above-named designs. The circuit of this receiver, with insignificant dorisovka and excluded obvious "mistakes" is provided on fig. 1.

having Creatively worked over the provided circuit, the author realized her following option (the Fig. 2). The circuit of the receiver is constructed taking into account recommendations [13] and other konstruntsiya listed and not listed in the list of references, and as theories stated in [1].

Should be noticed

that concept universal, probably, not the absolutely correct. It is possible to call rather a receiver base since the design allows to add easily a synthesizer of frequencies and the second transformation of frequency, having turned it in decent coherent the receiver. For more detailed acquaintance with these questions I suggest to download from a site MOTOROLA necessary documentation [11,12,13]. I will in passing notice what to make the receiver narrow-band it is possible and without resorting to the second transformation of frequency about what it will be told further.

the Receiver can be reconstructed by p in a range from 70 to 150 MHz, without change of face values of tuning elements. Real sensitivity of the receiver about 0.3 мкв. Supply voltage - 9 volts. It is necessary to notice that supply voltage МС3362 - from 2 to 7 volts, and МС34119 from 2 to 12 volts. Therefore МС3362 eats through a voltage stabilizer 78L06, target tension of 6 volts.

the Entrance cascade of the receiver is executed by p according to the traditional resonant circuit. The signal from the A1 aerial via the coil of communication of L1, arrives in an entrance contour of L2. Inductive communication with the aerial is executed not casually since it is only way to provide normal coordination with various aerials and in a wide range of frequencies [1,6,7]. For decrease in effect of shunting of a contour of L2 by entrance chains, and increase of its good quality and consequently narrowings of a pass-band and selectivity increase, incomplete inclusion of a contour is applied.

as an intensifying element is used by p the field KP307G transistor. The specified transistor has a high steepness of the characteristic and acceptable noise indicators. The same characteristics has two-barrier КП350, but he strongly is afraid of a static electricity, besides demands additional elements for ensuring shift on the second lock. All other transistors showed more the worst results both on strengthening and on noise.

the Strengthened signal is allocated with p on a contour of L3 which for the same reasons that L2, has incomplete inclusion. From L3 contour, via the coil of communication of L4 the signal arrives in the mixer. Such circuit provides the minimum mutual influence of UVCh and the mixer, increases selectivity, and provides the maximum coordination with the entrance cascade of the mixer, vypolny according to the differential circuit.

From internal the heterodyne in the mixer arrives basic frequency. Basic elements a heterodyne are C7L5 and the built-in varikapny matrix, changing tension on which the R6 resistor, it is possible to carry out insignificant reorganization on frequency. The R5 resistor is intended for "extension" creation. In principle R5, and C6 is possible for R6 ислючить, having connected the 23rd leg of MC3362 to a positive wire, and reorganization to carry out the elements C7 and L5. From the 20th leg a signal the heterodyne can be submitted on a synthesizer of frequencies, and operating tension should подавться in that case on the 23rd leg.

the Signal of raznosny frequency in 6,5 MHz (but can be and 10,7 MHz and 5,5 MHz, it was checked) moves on the pyezokeramichesky Z1 filter and further, passing the first UPCh and the second converter, on the second UPCh, the limiter and the phase detector.

From the phase detector, through FVCh on С13R9, frequencies providing a cut is higher than 5 KHz [2,3], the signal arrives on the LF amplifier executed on the bridge circuit, on MC34119 chip. Unlike 174 series this amplifier has considerable strengthening, high stability to self-excitation, low level of own noise, very high efficiency and small quantity of hinged elements. The target capacity on loading of 20 Ohm makes about 0,2 W.

If the receiver is planned to use p as broadband broadcasting, I recommend to change C13R9 values on the basis of recommendations [2,3], or to exclude this chain in general.

of the Detail and design. Unfortunately, the option of the receiver was not finished to "box" option. First it also it was not required, and secondly, process "is much more interesting to the author than knowledge and creation", rather than "a combing and a vylizyvaniye". Therefore the printed-circuit board, wishing to repeat this design, it is necessary to plant. By the way, it is necessary to do it even in the presence of drawing since often there are no those elements which were used by the author. And the circuit is rather simple, therefore difficulties with it should not be.

the Model payment which was used by the author has the sizes of 100х30 mm. also it is executed from bilateral folgirovanny стеклотекстолита, thickness of 1,5 mm. All details are located from printing conductors (the benefit of an opening it is not necessary to drill), and the second party is used as the screen. On how many it is good, I do not undertake to tell. I have a suspicion that it promotes emergence of parasitic capacities. If to look at industrial VHFs and DMV blocks, all of them are for some reason executed on a unilateral folgirovaniye. Resistors, condensers and electrolytic condensers can be any type. Tuning condensers of PDA type, but can be and others. The R6 resistor it is desirable to use the multiturnaround. The contour of LC of the frequency detector is taken from the import receiver (Chinese) and should be with a green or dark blue coloring. The capacity of such contour on frequency of 10,7 MHz makes 90 пф. Therefore for frequency of 6,5 MHz the additional capacity of Ca - 150 пф, and is necessary for frequency of 5,5 MHz - 250 пф. [14]]

Pzokeramichesky фильт Z1 can be any type. Though the chip is calculated on a target impedance the 300th ohm (for 10,7 MHz) and 1,5 lump on entrance (455 KHz). Nevertheless all filters work normally. It is necessary to notice only that filters happen different even for one frequency and have different pass-bands, somewhere 10-20 % will cause a stir from working frequency and consequently also selectivity will be. Besides on frequencies of 6,5 MHz and 5,5 MHz, except the strip are issued also rezhektorny (overwhelming) filters. They are marked usually by one point, and strip - two.

of the Coil of inductance of L2, L3, L5 have an identical design. They are reeled up on frameworks in diameter of 5 mm (such frameworks are used in SKM and SKD of TVs 3 and 4 of generations), the silvered wire of 0.7 mm and have on 5 rounds. Length of winding of 6 mm. Coils are located vertically. In coils there is a core. Brass for work in the top part of a range (140 MHz), or ferromagnetic for work in the lower part of a range (70 MHz). The coil of communication of L1 has 4 rounds (a round to a round) PEL 0,3 wire at the top conclusion of L2. The coil of communication of L4 has 2 rounds (a round to a round) PEL 0,3 wire at the top conclusion of L3. Branch at L2 and L3 is made from the middle.

All a contour paid off with the help [14], proceeding from the following reasons. Length of winding - 6 mm, quantity of rounds 5 + 1 (the additional round considers length of branches and inductance of paths), diameter of winding of 5.5 mm (0.5 mm consider a winding thinness). After calculation we receive L=0.13мкгн. For control for frequency of 108 MHz, capacities of condensers should be the following C1=С4=17 пф. Heterodynes works below accepted frequency, and the varikapny matrix is in addition connected to a contour with the minimum capacity about 5 пф, from here C5=19-5=14 пф.

Settlement results almost ideally coincided with practice at the accounting of capacity of installation 2-3 пф and capacities a source drain in 2 пф. (17-3-2= 12 пф. This capacity also showed С1 and С4.) Limiting frequency a heterodyne - 140 MHz, and taking into account the brass core - 150 MHz.

For those who wishes to use the receiver on 144 MHz or above, I recommend to reduce number of rounds of coils L2, L3, L5 to 4. If the receiver is planned to use as broadband broadcasting, I recommend to change C13R9 values on the basis of recommendations [2,3], or to exclude this chain in general. UNCh Control is not required to p by

. Probably it is required to pick up R12 value for optimum value of strengthening and a LF pass-band as it is recommended in [4]. For FD control, пьезофильтр it is disconnected from the 19th leg and on it the frequency modulated signal with frequency of chosen PCh is given. I, for example, used the ordinary quartz generator according to the three-point circuit, with varikapy included consistently to quartz, modulating it the ZCh usual generator on one transistor from [2]. For control a heterodyne in the set range, I used the same VCh the generator, having altered it in the LC generator, and the same one-transistor ZCh. The generator settles down near the receiver at which UVCh (отпаивается the R4 resistor is disconnected) and the C7 condenser makes control for frequency of the generator. Then UVCh is connected, capacity С1 is established minimum, and L3 is arranged by the C4 condenser on the maximum loudness of a signal. Then the aerial (a piece of a wire of 50-100 cm) is connected and control of a contour of L2 by the C1 condenser is carried out. Final exact control of contours be made by tuning cores. If UVCh starts to be raised at the exact L2 control, I recommend to leave it a little upset, above accepted frequency.

Some remarks. The specified receiver can be altered in narrow-band option. It can be made in several ways:
1) to Include the second transformation. It is easy for making having looked at the circuit represented on fig. 1. It is necessary to choose quartz on 465 KHz higher or below the first PCh. It is desirable to make the first PCh 10,7 MHz for selectivity increase on the mirror channel. The contour of LC is necessary for using from PCh Russian transistor SV-DV-KB receivers. Use of contours from import (Chinese) receivers with a yellow coloring - is problematic, since they have frequency of control of 455 KHz, and to hold on it to 465 KHz not always it is possible. As the Z2 filter (fig. 1) can be applied FP1P-024, FP1P1-60.1 or something similar;
2) Can be used and single transformation if to replace Z1 (fig. 2) with ready quartz filter FP1P1-307-18 with frequency of 10,7 MHz and a pass-band of 18 KHz and very big sizes, or on MCF-10,7-15 c the same frequency and a pass-band of 15 KHz. Sizes of this filter much less than 15х10х10 mm. />/>

However at such option is also serious problems. Which essence that target LF tension of the frequency (phase) detector, is less than subjects, than is wider a strip of a contour of ChD and less deviation of frequency. (It in addition explains, why at narrow-band the WC is used low PCh). Therefore for obtaining sufficient loudness it is necessary to narrow a pass-band of a contour of LC (that is very difficult), or before UNCh to put the additional amplifier. And it is noise! There is one more option. Instead of LC to use the quartz resonator on 10,7 MHz as it is realized in [5]. However МС3362 it was not developed for such application and the author did not test it. For wishing it to do I recommend to use almost similar chip МС13136, but developed under the quartz resonator in ChD, instead of LC. Besides, both options have common fault. At a narrow pass-band there are very appreciable frequency fluctuations a heterodyne, i.e. it is required either a synthesizer, or quartz stabilization.

One more supervision. In the receiver (fig. 2) the author executed double transformation, having made the first PCh of 10,7 MHz, and the second 6,5 MHz. The result was depressing. The receiver hardly accepted radio station with capacity in 1,5 Kw of 2-3 km which were at distance. Replacement of a chip of results did not give, I did not carry out further trial.

For wishing even more to reduce the sizes of the receiver I recommend to use МС3363 which has the transistor built in the case for UVCh, and also shumopodavleniye system. But it is issued only in the planar case that complicates its installation, and is more expensive considerably, about 200-250 rubles, against 25 rubles МС3362. As much costs and МС34119.

Some passing conclusions. Eksperementiruyu with the given receiver, and as with VCh and PCh blocks of the Chinese receiver, the Urals Car, the Melody-106, i.e. I use VCh from the developed receiver, and PCh from another and on the contrary, the author made the following some conclusions, probably the already known:
1) quality of the receiver (sensitivity and selectivity) generally is defined by quality PCh-ChD of the block and practically does not depend on block VCh;
2) filters of the concentrated selection (Social Insurance Fund) in PCh blocks have considerably the best indicators, than pyezokeramichesky and even quartz since allocate a signal in a strip of frequencies, instead of cut out all strip, together with noise. />/>

Literature.
1. Barkan V. F., Zhdanov V.K.Radiopriyemnye устройства.1972г.
2. Bunimovich S.G., Yaylenko L.P. Equipment of amateur one-band communication., 1970г.
3. Muravin V. Hearing aids. For the aid to the radio fan. Release 93, page 42.
4. Grigoriev B. UZCh of the transistor receiver for the aid to the radio fan, Release 93, page 73.
5. Besedin V. Radio amateur phone. Radio 10, 1993г., page 29.
6. Kirik O. Melodiya-106-stereo. Radio 3, 1979г., page 31.
7. Hmartsev V. All-wave receiver радиокомплеса. Radio 8, 1974г., page 31.
8. Stasenko V. Automobile radio station of a range 144-146mgts. Radio fan 2, 1992г., page 20
9. Frolov E., Dolmans of Century, Berezkin N. of WC VHF the receiver on 145 MHz. Radio 3 1991г., page 22
10. Poles of Century of VHF of a WC rdiostantsiya. Radio 10, 1989г., page 30
11. Technical specification on chip МС3363. Internet site Motorola.
12. Technical specification on chip МС3362. Internet site Motorola.
13. Additional remarks on application МС3362, МС3363. (AN980.PDF) Internet site Motorola.
14. Strange D. The program for IBM PC by calculation of contours. />/>/>/>/>/>/>/>/>/>/>/>/>/>

Alexey Bolshakov

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Universal VHF of a WC receiver (70-l50mgts)

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