Now I realize that, the bad thing is that in the past I desoldered a lot of them without realizing that their serial numbers won't help me.I have a few salvaged ones here. Before removing them from the original board I write their purpose on the side of the can, for example "455KHz First IF", "10.7MHz discriminator" to help identify them later. In most cases I do as you did and remove the old wire and wind a new one as needed.
Strangely enough, those capacitors looks like that older big SMD resistors to me. It's kinda hard to remove them, I've broken of the part of plastic along with pin while doing that, but I managed to glue it back.Be careful to remove any capacitors, you often find one sitting in a slot between the pins, if you leave it in place the coil will not work.
DESIGNATION DESCRIPTION/MARKING PART #
T1, T2, T3 10.7 MHZ IFT 42IF123-RC
Q1 THRU Q8 2N3904 2N3904
U1 78L05 TO92 PACKAGE 78L05ACPRAG
U2 LM386 8 PIN DIP NJM386D
X1 THRU X5 10 MKZ CRYSTAL FOX100-20-LF
C1 THRU C15 .1 UF DISC LABELED AS 104 SR2115E104MMA
C16 THRU C21 390 PF COG BLUE, NO MARKING K391J15COGF53L2
C22 33 PF COG BLUE BODY 33 RPE5C1H
C23-C28 68 PF COF BLUE BODY NO MARKING FK28COG1H680J
C29 .047 UF 140-50Z5-472M-RC
C30-C33 10 UF 16V UVR1E100MDD
C34-C35 100 UF 25V B41827A5107M00
C36 50 PF TRIMMER 659-GKG50015
D1 1N4001 512-1N4001
R1 33K ¼ COLOR CODE OR-OR-OR-GD 291-33K-RC
R2 22K 1/4 W COLOR CODE RD-RD-OR-GD 291-22K-RC
R3 2200 1/4 W COLOR CODE RD-RD-RD-GD 291-2.2K-RC
R4, R5 10K 1/4 W COLOR CODE BR-BK-OR-GD 291-10K-RC
R6 1000 1/4W COLOR CODE BR-BR-RD-GD 291-1K-RC
R7,R8 6800 1/4 W COLOR CODE BL-GY-RD-GD 291-6,8K-RC
R9- R10 1500 1/4 W COLOR CODE BR-GN-RD-GD R291-1.5K-RC
R11 THRU R20 3300 1/4 W COLOR CODE OR-OR-RD-GD 291-3.3K-RC
R21 THRU R23 10 1/4 W COLOR CODE BR-BK-BK-GD 291-10-RC
R24 R25 470 1/4 W COLOR CODE YL-VI-BR-GD 291-470-RC
R26 100 1/4 W COLOR CODE BR-BR-BR-GD 291-1K-RC
R27- R28 330 1/4 W COLOR CODE OR-OR-BN-GD 291-330-RC
RFC1-RFC2 470 UH YL-VO-BR-GD BLUE BODY 542-78F471-RC
VR1 5K AUDIO TAPER RV120F-10-15F-A5K
VR2 100K AUDIO TAPER RV120F-10-15F-A100K
VR3 5K LINEAR TAPER RV120F-10-15F-L100K
J1 SPEAKER JACK 1/4" 161-MJ159M-EX
J2 PWR JACK 5.5 MM/2.1MM 163-4304-E
J3 SO239 ANTENNA CONNECTOR USER SUPPLIED
KNOBS USER SUPPLIED
12V DC POWER SUPPLY USER SUPPLIED
CABINET USER SUPPLIED
The datasheet parameters allow to locate a similar part or even wind it yourself.
Can you give me more information how would I do that? Recently I have bought an inductance meter, but I have mixed feelings about its accuracy. I also have the scope.You could use any of the ones in your picture if you remove the original coil and tuning capacitor then wound our own coil back on the plastic former.
I realized that, but I watched videos of people testing it and the voice quality was very good...If you look closely at the circuit and do some mental rearranging, you will note it is almost the same as the VK3AJG design, the only significant difference being the 10MHz IF filter and BFO which make it a superhet design rather than direct conversion.
Right now I haven't analyzed those changes, but I'll keep them in mind when the time comes. Maybe I will post a new topic for this receiver in the appropriate forum, especially cause your hints are extremally helpful and I appreciate that. Thanks!Personally I would make some changes:
rfc02 would be a 10K resistor.
C11 would be 1uF
C29 would be across the volume control instead of to +12V
D1 would be a varicap instead of a 1N4001
however, it should still work as it is.
You could use any of the ones in your picture if you remove the original coil and tuning capacitor then wound our own coil back on the plastic former.
Those figures are for pre-wound and tuned transformers, ready to drop into specific applications. It would be better to add turns to get the right inductance which you can calculate then measure as you wind the coil. The resonant frequency depends not only on the coil but the capacitance across it (f=1/2*pi*sqrt(L*C)).
You could use a wide range of coils as long as the capacitance across them tuned them to 3.5MHz
No particularly accurate components are required, except for one (or more) accurately known "external" capacitors used to calibrate the meter.
The two 1000pF capacitors ("C" and "Ccal") should be fairly good quality (stability is important, accuracy is not ;-). Polystyrene are preferred. MKT are fine, as are Mica. Greencaps tend to drift in value too much. Avoid ceramic capacitors. Some of these can have high losses (and it is hard to tell).
The two 10uF capacitors in the oscillator should be NEW tantalum ones (for low series resistance/inductance). Alternatively, "low ESR" aluminium capacitors can be used. You could add a 0.01uF ceramic capacitor in parallel with each, "just to be safe".
The 4MHz crystal should be a genuine 4.000MHz one, not something approximate to 4MHz. Every 1% error in crystal frequency adds 2% error to the indicated inductance value.
The relay should be a low current one. The PIC can only provide about 30mA of drive current. The relay should be able to "pull in" with 4.5 volt applied to the coil. (Most 5volt reed relays will be OK).
Don't forget the "catch" diode across the relay coil!
Measuring range is from 0 to >0.1uF for capacitance and 0 to >10mH for inductance.
Expected accuracy is +/- 1% of reading +/- 0.1pF or +/- 10nH
Detailed here within is a simple crystal controlled receiver originally developed to operate on a single fixed frequency to monitor QRSS transmissions on the 40m amateur band. It can be easily adapted to operate on any of the HF amateur bands by simply altering key component values.
Design concept:
The design concepts primary goals were as follows:
Small and compact design.
Simple, easy to set up and easy to replicate design.
Using easy to source readily available, economic components.
Good performance on today's crowded HF amateur bands.
Receiver description single conversion super heterodyne.
The RF front end section comprising TR101,TR102,C102,C103, & C104 forming a three element Pi band pass filter impedance matched to both the antenna and first mixer IC101 (NE612). Although there is no RF pre-amplifier, the mixer IC101 does provide around 8db conversion of gain.
The receiver operating frequency is set by frequency of crystal Q101 (FQ101 = Frx + IF or FQ101 = Frx - IF). My receivers operating frequency is set to 7.0008MHz in order to monitor QRSS activity on the 40m amateur band, therefore (FQ101 = 7.0008 + 8.0000) 15.0008MHz. In reality the crystal used was 15MHz fine tuned to the correct frequency with padding capacitor CV101. Although it could be easily modified to cover a small section of a single amateur band i.e. the CW section, or for that matter part of the SSB section whilst still maintaining good frequency stability by adopting more aggressive VXO tuning of the crystal local oscillator.
The IF section comprising Q102, Q103, Q104, Q105, C110, C111, C112, C113, C114 form a four pole crystal ladder filter, this is where the bulk of the receivers selectivity is achieved. Here as with the RF front end there is no amplification provided at IF, although again there is around 8db of gain provided by the product detector IC102. Sideband selection being achieved by appropriate adjustment of CV102.
The AF section comprising of active devices T101 and IC104. Components C118, C119, & L103 forming a Pi low pass filter prior to T101 the audio pre amplifier, volume adjustment by RV101 before the final stage the AF power amplifier IC104 capable of providing several watts into an 8 ohm speaker.
The voltage regulator IC103. Providing a stabilised 8volt supply to both IC101 & IC102, this improves the frequency stability of the receiver at less than 15Hz in the first 60 minutes after switch on. Please note bypass capacitors C134 & C135 are essential to eliminate any noise generated by the voltage regulator IC, furthermore chokes L101 & L102, and bypass capacitors C132 & 133 are essential to ensure no noise is introduced to the two mixers IC101 & IC102.
Okay, so now let's get more specific.
I want to build SES080 QRP transceiver.
Here is the .doc instruction and the .pdf scan of original article:
View attachment 141085
View attachment 141086
Here is the components list:
As you see, it requires three IF cans: 10.7 MHZ IFT 42IF123-RC.
First, I have looked at Aliexpress, because that's where I but parts.
Obviously, there was nothing like that IF can.
Then I checked the Google,which led me to Mouser. Unfortunatelly, the 42IF123 is marked as "Obsolete" and "Not Available" in Mouser.
The only place which is apparently selling such cans, each for 3$ (!!!), is located in Southern Australia.... and I live in the Europe...
Is this really that hard to get proper IF cans? Or maybe can I somehow replace them, or find the replacements in the old electronics junk?
Bear in mind they are not being used as 10.7MHz IF transformers. The reason those particular types were chosen is they are designed to work at 10.7MHz, a little higher than 3.5MHz, and the nature of LC parallel circuits is that adding external capacitance lowers the resonant frequency. You could use a wide range of coils as long as the capacitance across them tuned them to 3.5MHz. You could use any of the ones in your picture if you remove the original coil and tuning capacitor then wound our own coil back on the plastic former.
If you look closely at the circuit and do some mental rearranging, you will note it is almost the same as the VK3AJG design, the only significant difference being the 10MHz IF filter and BFO which make it a superhet design rather than direct conversion.
22uH
4*0.05us
5.7*0.05us
33uH
4.7*0.05us
6*0.05uS
4.7uH
1.9*0.05uS
2.2*0.05uS
10uH
2.8*0.05uS
3.2*0.05uS
11uH
3.5*0.05uS
3*0.05uS
which, as seen above, gave me range around 5.71MHz-6.66MHz VFO range which is 4.29MHz-3.34MHz tuning range because it's a superhet.11uH
3.5*0.05uS - 5.71MHz
3*0.05uS - 6.66MHz
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