2.2. UFS472,5 ein Sendeumsetzer Kurzwelle / 630m
During past electronic projects, transverters were integrated in housings of old UFS radios. Those radios were commonly used by the public authorities in the former German Democratic Republic. Due to positive experience and the still good availability of UFS parts the transverter for the 630 m band was also built inside a UFS housing. The circuit follows this of G3XMB with minor modifications. To improve the sensitivity and selectivity of the receiver, preselector and preamplifier stages were added which required an additional relay for RX / TX switching. As an LO a 4 MHz / 5 V crystal clock oscillator was used. The FET PA received a separate line for its drain voltage supply. Low pass and RF choke elements were implemented on ferrite rings. Preceding the mixer stage an RF VOX was added. The 470 kHz output signal can be monitored by the LED of an RF indicator circuit.
The photo on top displays the 630 m transverter in the UFS housing
The bottom photo shows the base plate. The second foldaway frame is still empty.
