Chip TA2003p, its Korean and Chinese counterparts: KA2297 and CD2003 are still popular with radio amateurs. In 1997, the magazine "Radio" for the first time in the Russian Federation published a circuit of the AM-FM radio receiver on the TA2003r microcircuit. Even then, insufficient sensitivity and selectivity of the receivers on the TA2003p, assembled according to the standard scheme, were noticeable. To improve the quality of radio reception, AM and FM intermediate frequency amplification stages with resonant circuits were added to the circuit. ... In the media, there are options for additional selective cascades of the UPCH-FM for the TA2003p microcircuit with additional ceramic filters, which, with its low sensitivity, are not particularly needed. Figure 1 shows the last version of the modified receiver circuit. The designation of its parts continues the diagram from. According to the modified scheme, several radio receivers were assembled on the TA2003r and KA2297 microcircuits. All of them showed stable, without a tendency to self-excitation, work with a noticeable improvement in sensitivity and selectivity. Since simple ceramic filters are not able to attenuate signals by more than 40 dB, the frequencies of which are hundreds of kHz away from their bandwidth, in the FM (VHF) bands, especially VHF-1, powerful radio stations have ceased to "overlap" each other. In the AM (CB) range, the reception of weak stations improved, while the noise level did not increase. Additional resonant stages are installed after the main filter of frequency selection of the IF AM and FM amplification paths, so they do not disrupt the operation of the microcircuit. The increase in sensitivity is confidently regulated by the standard AGC of the microcircuit. The revision did not complicate the setup of the receiver. In fig. 2 shows a drawing of one of the options for the RP board according to the diagram in Fig. 1 and the location of parts on it - fig. 3. The board is made of one-sided foil-clad PCB 1.5 mm thick. All circuits are taken from imported radio receivers: L7-8 from the IF-AM filter at 465 kHz with a yellow core and with a tap from L8 - pin 2; L9-10 for IF-FM at 10.7 MHz with orange core; L2 FC discriminator with green core, they all have built-in capacitors. Coil L4 of the CB local oscillator with a red core, without built-in capacitor. Holes for shielded coils 10-10-14 mm in size are marked on the board. Between the VT9 collector, pin 2 of the L8 coil and its extreme pin 3 - a plus of the power supply, the L8 section is connected, which has a smaller number of turns. Coil L4 may not have a communication coil, pins 4-6, then it has a tap - pin 2, in this case pin No. 12 of MC TA2003r is connected to it, and to pin 3 of the L4 circuit - plus power. The L4 coil section between pins 2 and 3 has fewer turns than between 1 and 2. Because of these differences, it is advisable to ring all the coils before fabricating the board in order to correct the circuit layout. It is advisable to observe the phasing of the leads of the IF amplifier, indicated in Fig. 2 and 3, otherwise the probability of self-excitation of the circuit increases.

Transistors VT9 and VT10, except for those indicated in the diagram, you can use any: VT9 - F max. 100-500 MHz, V st. 30-50. VT10 - F max. 500-1000 MHz. In Art. 30-50, suitable for the location of the terminals. Capacitor C28 is soldered from the side of the conductors near L2 - L4. When tuning the IF AM path by rotating the L7-8 core, they achieve the maximum sound volume.

The tuning of the IF channel of the FM is carried out with the antenna turned off and the maximum volume. By rotating the L9-10 core, the maximum noise level at the output of the receiver is achieved, by rotating the L2 core, the noise at the output is reduced. This setting is repeated several times. Data on input circuits, setting ranges, ULF details and its tuning are given in. The receiver board is fastened to the case with four screws together with its back panel (cover). There are three mounting holes on the board. At the fourth attachment point, next to the KPE block, the screw passes between the board and the case, and goes into the hole on the case's fixing protrusion, located under the adjustment knob. Radio receivers assembled according to this scheme (Fig. 4) have been working well for many years. Their only weak point is the contacts of the VHF-1 - VHF-2 (FM) range switch, which had to be washed several times with a cleaner.

China is still supplying us with a large number of cheap radio receivers based on analogs of this microcircuit. For one of them, on the CSC2003 microcircuit (another analogue of the TA2003p), an additional selective amplifier PCh-FM was manufactured. In this unit, SMD resistors and capacitors of 1206 size and an L9-10 coil with dimensions of 8-8-11 mm from the old player are used. (Fig. 5). The block was placed on the receiver board on the foil side and connected to the gap in the conductor connecting the filter output Z1 and pin # 8 of the CSC2003 microcircuit. The part designations correspond to Fig. 1. At a supply voltage of 6 V, the resistance R11 is increased to 120 ohms. Receiver sensitivity and selectivity have improved.

BIBLIOGRAPHY

1) "Radio" 1997 №9 AM-CHM receiver with low-voltage power supply. A. Panshin.
2) "Radio" 1998 №9 AM-CHM receiver with low-voltage power supply. A. Panshin.
3) Site radiokot.ru/forum/download/file.php?id=133688
4) Site vrtp.ru/index.php?showtopic=19216&st=30
5) "Radio" 1998 No. 10 Color marking of contour coils ... A. Panshin.

Panshin Andrey. Moscow

Somehow in April, after reading the review of the constructor "Excellent radio (speaker) for mother-in-law", I remembered that I also have a mother-in-law and wondered whether it’s time to teach my kinder to solder-assembly, and at the same time to prepare a gift for my mother-in-law. summer cottage season. After digging around on aliexpress, I settled on this model - I liked the classic look and the large indicator.

Just in case, I ordered a couple of simpler AM / FM radio sets without an indicator from another seller, but the postal curve brought them to Blagoveshchensk, from where they have not yet arrived. I myself was traveling in distant countries at that time, but this is not a hindrance to a real shopper, a laptop and 3G Internet will always help to quench the itch of shopping. The seller sent the parcel very quickly and just as quickly it flew to Moscow. When I returned home, my wife had already received it and unpacked it, so lovers of unpacking and pimply anti-stress packaging film will be left without pictures today :)

Specification

• Size: 120x76x26 mm
• Display: 52x34 mm


• Range: 72-108.6 MHz
• Intermediate frequency: 10.7 MHz
• Power supply: 2хАА
• Operating modes: radio, clock, alarm

In a plastic bag with a clasp, the radio was almost as if assembled alive, and only two pieces of masking tape that held the body together spoiled the impression.


After peeling them off and opening the case, I found two printed circuit boards inside, one of which (indicator) was already soldered, a bag with other parts and a speaker. Unfortunately, I did not take photos during the assembly process, so I have to insert a photo from the seller.

And inside she has a neon

In addition, there was nothing else inside, no hints of the assembly process or diagrams, well, nothing at all. I had to launch aliexpress and see the seller's excuses in this regard, and they were there, he honestly wrote - "Note: When you receive it, please contact us to send Assembly Drawings or Schematic Diagrams to you, thank you." I wrote to the seller and after 5 minutes I received a response with a link to the documentation (a plus for the seller for efficiency). I downloaded from the link an archive packed rar with a bunch of documentation in Chinese, this is where the skills of reading comics would come in handy if I had them, but due to the lack of them I had to use my experience of radio amateurism. Judging by the number / volume of doc "s / pictures / presentations there is a detailed course for a novice radio amateur, a list of elements, the arrangement of elements, a schematic diagram, a block diagram, marking of radio elements, well, in general, everything, everything, everything, it's a pity just in Chinese, it would be interesting to read, but even just look these comics were nice and interesting.

Schematic diagram

The signal from the antenna through the capacitor C6 enters the base of the transistor 9018, on which the antenna amplifier stage is assembled. From the antenna amplifier, the signal goes to the first leg of the CD2003GP microcircuit at the FM tuner input, then the signal is mixed with the local oscillator signal (the local oscillator signal through the capacitor C12 is also fed to the frequency counter input on the display board). After mixing, the signal goes to the intermediate frequency filter (10.7 MHz) CF1 and from it goes to the input of the intermediate frequency amplifier on pin 8 of the CD2003GP microcircuit. Next, the amplified signal inside the microcircuit is fed to the FM detector unit and the resulting low frequency signal from the pin 11 of the microcircuit is fed to a low frequency amplifier made on a TDA2822M microcircuit, where it is amplified and fed to a speaker or headphones. On the transistor 8550, connected in parallel with the power switch, a cascade is made that turns on the receiver by an alarm signal from the clock microcircuit.

The bag contained a number of about such details.

Let's talk a little about printed circuit boards. The display board, as I said, was soldered, but maybe this is for the best, given the filthiness of my soldering iron and the difficulty of connecting the deposited leads of the LCD indicator.

Display board and clock buttons

In addition to the indicator itself and control buttons, there is a clock microcircuit on the board. In addition to the function of a clock, it also functions as a controller of the indicator / buttons and a frequency counter for displaying the frequency of the received radio station. As you can see in the photo, you just need to put the flexible contacts of the buttons in place and glue them on top with adhesive tape, nothing complicated and the assembly of the indicator board ends there.

Main board

The main board has both pros and cons. The pluses include more or less high-quality manufacturing, the presence of a mask and silk-screen printing with the location, designation and denominations of elements. The disadvantages include the fact that the board was not tinned. Despite the fact that it seemed to be covered with something like a flux, it was soldered very disgustingly, I would even say that it was almost not soldered. Having peeled off the only detail that I was still able to glue with a soldering iron, I decided to sand the board a little with sandpaper. I sanded it gently so as not to take off the mask, but apparently due to my excessive tenderness, this almost did not give an effect. Then I remembered that I had some kind of acidic flux and it went well - I tinned the board at a moment. After the acidic flux, I washed the board, dried it and started assembling. Then everything went like clockwork, even in spite of my ugly Chinese soldering iron. The assembly was not difficult and did not take much time, all this time the younger generation did not heed my instructions and regularly typed the soldering iron to learn from experience, I hope he will be able to assemble the following designers himself with minimal help.
Here's what we got.

Result. Inside view.

There were no installation errors, the parts were all serviceable and the receiver started working immediately after switching on.

Works

Customization. Turning the tuning knob, at first I was a little upset - the receiver showed that it receives about 61-90 MHz in the VHF FM range, where there are clearly fewer radio stations than in the FM 87-108 MHz range. I wanted to start aliexpress again, but then I suddenly noticed a small inscription on the front panel of the receiver "FM BAND 74.0-108.0MHz". Yeah, I thought, there were trimmer capacitors on the circuit, and I began to study the circuit intensively. "Yes, there he is!" - I exclaimed joyfully, poking my finger into the capacitor C1-1 and for sure - it turned out to be he.

Range setting - outlined in glam color

I set it to the upper frequency and got this range - 71.4-109.1 MHz.
This completes the setup of the receiver and I hammered the last nail into the coffin lid and tightened the last screw into the back cover of the receiver.

Let's talk a little about control bodies.
Behind the radio, there is an antenna and a battery compartment for two AA elements and the very last nail in the coffin lid. The length of the antenna in an excited state is only a miserable 35 cm.

Back view

On the left side of the receiver there is a headphone jack (mutes the speaker when headphones are connected) and a volume control. And on the right is the tuning knob. Yes, yes, unfortunately, the setting for him is with a pen, and not with buttons as it might seem at first.

Side views

The front panel contains the speaker grill, indicator and buttons - Power On / Off; Al On / Off; MINset; HEset; TIMEset; ALdisp.

Front Panel

Power On / Off is a latching button that turns the receiver on and off, and when the button is pressed, the receiver is turned off, when it is released, it is turned on.
When the receiver is turned on, the indicator displays the frequency of the received radio station; when the receiver is turned off, the indicator switches to the clock display mode.
Al On / Off - pressing this button sequentially turns on or off the alarm. This button works in the same way in radio mode.
To set the time, turn off the radio, then press and hold the TIMEset button and press or hold the MINset button to set the minutes or the HEset button to set the hours. These buttons do not function in radio mode.
Pressing the ALdisp button displays the time at which the alarm is set. This button works in the same way in radio mode.
To set the alarm, press and hold the ALdisp and TIMEset buttons and set the time with the MINset and HEset buttons. In general, any accordion player or saxophonist can easily cope with this task.

Let's summarize.
The radio works and works well, the CD2003GP microcircuit has an automatic frequency control unit and keeps the reception confidently.
The clock is working. The alarm clock works and turns on the radio when triggered. The accuracy of the watch is still unknown - it depends on the accuracy of the watch quartz.
The volume is quite high, but at maximum volume it starts to wheeze and choke, but what did you want from a speaker a little larger than a matchbox.

What we liked:

• Classic appearance
• Ease of assembly
• Reliability of reception and the ability to adjust the range of FM / VHF
• Quality board
• Common batteries
• Expected assembly pleasure received

What did not like:

• Unserved board, poorly soldered
• Fastening the back cover with one screw Thanks to deeprus for being vigilant, there are still two screws there.
• The clock only works in 12-hour format

What expectations did not come true:

• It was unclear from the description and a false impression was created that the receiver setting would be buttons; in reality, it turned out that the receiver is tuned by the variable capacitor knob and millimeter precision is required for tuning. On the other hand, for my mother-in-law, the simpler the better, so I don't write it down as a minus.

Conclusion: you can take it, but a little expensive for a receiver with an analog setting.

Oh yeah, I almost forgot.

SPECIFICATIONS

1. Range of received frequencies …… 88-108 MHz.

2. Sensitivity at a signal-to-noise ratio of 26 dB ……… 5 µV.

3. Frequency spectrum of the AF signal ... 30 ... 16000 Hz.

In recent years, broadcasting on the VHF-FM bands (VHF-1 and VHF-2) has been rapidly developing. Simple VHF-FM radio receivers, assembled on K174XA34 microcircuits, are very popular among radio amateurs,

K174XA42, KXA063, other similar ones, implementing the principle of superheterodyne with a low intermediate frequency. The pages of practically all radio amateur magazines are full of different versions of such radios. A wide variety of kits for assembling receivers on these microcircuits are available on the market. And despite the fact that with all efforts, such receivers work very mediocre (crackle, give out a low-frequency signal with "characteristic" distortions), the demand for these microcircuits does not fall.

The author of this article unsuccessfully went through quite a lot of albums of circuits and various literature, both over the past years and the most recent, trying to find at least one imported device built on foreign analogs of these microcircuits. It turns out that despite their "Western" origin, they are not favored in their homeland.

Perhaps such a demand among our radio amateurs is explained only by the extreme simplicity of receivers based on this element base. Many of them practically do not require any customization and are limited to a relative minimum of elements.

The simple VHF-FM receiver proposed in this article, made on the common TA2003R microcircuit, is intended to refute the persistent opinion that a VHF-FM receiver, with a high IF, cannot be configured without special devices. The author intentionally, when assembling and setting up this receiver, did not use measuring instruments, but built the circuit so that there was a minimum of hanging elements. The result is the circuit shown in Figure 1. As you can see, in terms of the number of mounted elements, it does not exceed the typical K174XA34 switching circuit. And the presence of one IF circuit, you see, is the minimum payment for good sound. The typical value of the intermediate frequency for TA2003P = 10.7 MHz, but since a wide range of radio amateurs more accessible piezoceramic bandpass filters at 6.5 MHz (or 5.5 MHz) from the sound paths of TVs such as USTsT, in this scheme the intermediate frequency is 6 , 5 MHz (or 5.5 MHz).

There is no input circuit (usually a non-tunable circuit tuned to the middle of the range is placed at the input), the signal from the antenna through the blocking capacitor C1 goes directly to the input of the RF amplifier, which is part of the microcircuit. This RF amplifier is resonant, it is loaded on the L1 C9 C2 VD1 circuit, which is tuned within the range, simultaneously with the heterodyne, using the VD1 varicap.

The heterodyne circuit L2 C3 C4 VD2 is connected to pin 13 A1, it is rebuilt using the VD2 varicap. The variable resistor R1 plays the role of a tuner, but it can be any other source of reference voltage that can be changed within 0 ... 3V, for example, a block of fixed settings on several variable resistors or a digital voltage synthesizer. The R2 R3 C5 circuit serves to decouple the RF signals from the DC tuning voltage.

From the output of the frequency converter, the IF voltage is fed through the piezoceramic filter Z1 to the input of the IF amplifier. In the phase-shifting circuit of the frequency detector of the microcircuit, the L3 C7 circuit is tuned to the IF frequency of 6.5 MHz (or 5.5 MHz). This circuit can be replaced with a quartz resonator at such a frequency, but due to its absence in the free market, a circuit is used. Resistor R4 serves to lower the Q-factor of this circuit in order to reduce the nonlinear distortion of the received AF signal.

In the receiver, you can use piezoceramic filters in plastic three-pin housings FP1P8-62-01 (at 5.5 MHz) or FP1P8-62-02 (at 6.5 MHz), filters in metal-glass housings are also suitable, but this will require changing the board layout.

Coils L1 and L2 do not have frames, for the range 88-108 MHz they must contain 6 and 5 turns, respectively. They are wound with a 0.43 PEV wire on a drill shank with a diameter of 3 mm. After winding and cutting the leads, the resulting "springs" are removed from the drill and installed on the board. When adjusting the receiver, the inductance of these coils is changed by compressing or stretching them.

The L3 coil is wound on a ferrite rod with a diameter of 2.8 mm and a length of 12 mm (a standard trimmer from the MC circuit or TV decoder 3-USTsT). It contains 14 turns of wire PEV 0.43.

Varicaps KV109 can be replaced with KV104 or KV121. The TA2003P microcircuit can be replaced with the TA8184P, which coincides with it in terms of pinout and characteristics.

All parts, except for the resistor R1, are mounted on one small-sized printed circuit board made of one-sided foil-clad fiberglass. The dimensions of the board are 50X33 mm.

Customization. After checking the installation, connect an antenna to the antenna input of the receiver, the role of which can be played by a piece of mounting wire about a meter long, as well as power supply 3-4.5 V and any UMZCH, for example, on transistors or on a K174UN14 microcircuit switched on according to a typical scheme. A low hiss should be heard in the speaker turned on at the output of the UMZCH. Slowly rotating the rotor of the resistor R1, try to tune the receiver to any radio station. If this fails, squeeze or stretch the L2 coil a little. After receiving the station, adjust the L3 coil (by carefully pulling out the core) so that the sound is with minimal distortion. If necessary, connect a 20-50 pF capacitor in parallel with C7.

My aunt gave me her tape recorder for repairs for repairs, she says, they say, nothing works in it. The device had a CB - player, cassette player and radio. And nothing worked

Considering first the CB - player. It became clear that he could not be brought back to life, well, then we will switch to cassettes. The motor just went out of order, nothing, replaced it. Well, now I got to the radio. The breakdown was simple and understandable, just one electrolyte dried up, just in case, replaced everything. I looked at the microcircuit there was TA2003, it's cool, I haven't seen such ones yet and decided to listen to what she can do

It turned out that a rather not bad receiver is obtained from it, the sound is clear, high-quality clearly catches all the stations that are caught by all the receivers that I have, only the sound quality is at the same level. I thought not badly and by running to the network to look for the TA2003 datasheet I want to collect the same for myself.

Here is a schematic of this receiver on TA2003

The set of elements used:

C1,2 = 1000pF
C3.4 = 10mF
IC1 = TA2003
R3,4,7 = 4.7k
R5 = 47-100k
R6 = 47k
Z1 = 10.7MHz
ZQ1 = 10.7

This receiver does not require anything else, it is powered by 3 - 9V
This is the TA2003 microcircuit

Well, that's all, collect, tell us about your impressions. Good luck with the assembly

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