13 December, 2013

Home made 144MHz. transverter


Huh? Home made ​​transverter.

 How difficult and expensive to buy transverter to 144Mhz. I decided to order a new one and it Velka with pleasure!
The basis of the classics ... mixer who serves on TX & RX and high-quality filter to miss the receipt and delivery.
It turns out big but I do not like mini things, and other elements are "normal"!
The filter consists of three coils (silver) and air trimmers ... the coils need to be away from the weight of 10 mm and between them came bulkhead!
That's it! Below you is a photo comic creation of printed circuit boards to soldering filter ... of course filter tested and tuned by using the dip-meter!

Without it, it is quite difficult to do.



All activities and the construction of the high frequencies are performed on double press for greater good grounding and various problems that can occur ... fluctuations, etc.?
Soldered, measured and tuned ... input and output circuits .. there still baffles come from vetronita!
Fine tuning is done when all the parts are soldered, TX & RX is close to 50 ohms so as to adjust the working conditions!
Here the input air trimmers and exit with "ordinary"! Excellent .... 5 turns and 10 pF, and here we are .. at 144 Mhz .... plus or minus 10 MHz up and down ..... without Dip meter is not known where the circuit works? There somewhere? And it can vary up to 20 Mhz? Ham is not one if you do not know telegraphy and has a grid dip meter !


It is after the mixer section .... the mixer has a of certain loss, so after he puts a good FET J310 and resonant round at 28 MHz in the performance the PI and it is adapted to the impedance is 50 ohms!
Transverter is connected to the base unit with a coaxial cable 50 ohm!
On the picture you can see ... blue .... small relay at the entrance to the transverter to switch TX & RX,
  pot with a wheel of 28 Mhz elements and FET and mixer SRA-second

So connected LO "bricks" of 116.000 MHz and the output is connected to the Icom IC-703 at 28 MHz.
The thing hinder it working and the signal from the Dip-meter hear thunderous!
Weld the entrance area .... VF and put CF300 gas fet .. purchased on eBay by 1.2 E. piece ...

  Test and second LO .... this with a crystal of 116.000 MHz .. crystal KWG and exactly at the frequency!
The second picture .... signal generator that goes high and working UFB ... miracle of instrument

Now we need to solder blocks, electrolytes and small resistors and 100 mA stabilizer,
The CF 300 should be stabilized voltage 8 or 9 volts.
Last fet mounted and from below so that connections are as short as possible in its surroundings.
First, set the frequency 144,478 MHz where our local beacon and immediately heard.
Furnished circles ... input filter and the strongest reception by the meter!
Barriers are not yet built and drive does not fluctuate ... operate normally.
Well .. it's a double press on the plate ... weight up and down lines.
Here's a picture .... second round after a fet?
It can be seen that the air trimmer almost completely open ... need to play with the branch and a little constrict coil ... with contraction circle goes on a lower frequency.
Thus, the trimmer is a semi open ratio L / C is good ... these are all little things that need to know when these constructions.


Soldered bulkheads between the input and the filter.

Here's a little "paper"!
From the first scheme is used ... filter .. mixer and splitter rx-tx after him, and transmit and receive part of the MOSFET!
From the other was taken post mixer amplifier with J310!
The second scheme is a complete transverter.

Draft .... the upper hand ... this is crossed out on the double Vitroplast dimensions are 23x8 cm!

 Soldered to the output section .... BF964 MOSFET and goes out 5mW.


                                                           To be continued , little HI !

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