Baluns and Ununs

SRR (Romanian Society of Radioamateurs) is manufacturing a small range of Baluns and Ununs suitable for all HF-100W rigs.

Niste antene artistice

Un amic are o fotografie tare reusita a unor antene.

GPS for Kenwood TM-D710

I was looking for a compact solution for APRS mobile operation. First, I was started with a HOLUX GM210 "mouse" GPS.

The GPS unit was powered from a little homebrew stabilizer from the 12V socket. The same case was hosting the connection between the radio and the GPS unit.
But, this solution was to messy for my auto because involved a lot of wires and boxes.
So, I started to look for a more compact solution.
And this is what I made: a little box with the GPS module inside among a double RJ45 connector. The connector is needed to have the +5V supplied directly by the radio.
At the time of making the project, I had to choose from where to have the 5V: from the remote head or directly from the radio.
The remote head of the radio is powered at 10V and has some LP stabilisers inside. The LP stabs was evaluated and the conclusion was that they must not be stressed with the supplementary current surged by the GPS unit.
Instead, I choose the main 10V from the radio, available directly from the RJ45 cable. So, I used 2 RJ45 female couplers, already with straight connections between pins.
The result is in the pictures. The case is a half of the initial housing which host the first stabilizer.
In the box is the Holux GM210 module, a LM7805 stabilizer and the conections.

"Restitutio"

Sub numele de "Restitutio", Societatea Romana a Radioamatorilor a demarat proiectul de transpunere in format electronic a cartilor despre radioamatorism scrise in Romania.
Mai multe detalii aici.

RTP-MF

RTP-MF este un radiotelefon produs in Romania dupa licenta Ericsson, care facea parte din SRA (Svenska Radio Aktiebolaget). Aparatul era realizat la FEMI (devenita IEMI). Prin anii 80, am impresia ca a fost facut si la Electronica industriala. Nu sunt sigur, trebuie cercetat!

Butucanos, greu, realizat din aluminiu turnat sub presiune cu pereti despartitori pentru ecranarea modulelor, scula a facut parte din dotarea Militiei, a Armatei si a Securitatii. La origine denumirea era; SRA PN74, unde "74" probabil ca este anul in are a fost proiectat. Informatii recente arata ca "7x" reprezenta versiunea in functie de banda de lucru.

71 - 35/41 MHz

72 - 68/88 MHz

74 - 146/174 MHz.

Este un aparat tranzistorizat, capabil sa livreze 1,5W in benzile joase si 0,8W in VHF. 

Modelele originale aveau 0.8W in benzile 1 si 2 si 0.6W in banda 4.

Frecventa de emisie si cea de receptie erau generate de un oscilator cu cristale de cuart, aparatul avand 6 canale simplex sau semiduplex. Foarte interesanta este conceptia de generare a frecventei: se folosea un oscilator de 10,7 MHZ, pe care se aplica si modulatia FM pentru a fi adaugat la frecventa XO. Astfel, se folosea pentru un canal simplex un singur cristal. La receptie, aparatul avea dubla schimbare de frecventa si SQ bazat pe componenta de inalta frecventa din zgomotul de banda. Scula misto de muzeu! Principala problema la acest aparat este tranzistorul de comutare emisie-receptie, T522 (plansa 1c), un BC PNP situat chiar langa comutatorul de volum, pe coltul placutei cu oscilatorul de 10,7 MHz. Acesta are obiceiul sa crape la manipulare prin scurtcircuit intre baza si carcasa (parca, uf, au trecut atatia ani de cand erau visul meu de radioamator si le puneam pe picioare!) Mai jos sunt si schemele electrice ale aparatului.

O brosura de prezentare din anii 70 se poate descarca de aici.