ANTENTOP- 01- 2009, # 011

Tube AM Radio Station for the 160- meters

By: Igor Grigorov, RK3ZK

Technical Data:

TX: Output RF Power not less the 3 Wtts

RX: Sensitivity not less the 2 micro- V

The radio station consists of from a separate receiver and transmitter. Figure 1 shows schematic of the AM- radio station.

Transmitter: It is made on VT1, VT2, VT3, VT7. VT1 is a voltage stabilizator for VFO (made on VT2). L1C1C2 should be covered frequencies 900-980-kHz. L2C5 is tuned on 1900-kHz. VT3 is PA for the transmitter. L3C2 and S3 is ATU for the PA. The circuit should match antenna having Z from several Ohms up to several kOhms with the PA. S1 is switch for tuning VFO to calling station. S2 is switch to change mode AM/CW. VT7 is audio modulator of the TX. At AM mode the PA tube VT3 is switched to bridge with VT7. At TX relay K1 is switched high voltage to PA and shortened the 3-rd grid of the VT3 to the ground.

Receiver: It is made on VT4, VT5 and VT6. VT4 is a voltage stabilizator for the RX. VT6 is RF- amplifier for the RX. L7C23 is tuned to 1900- kHz. Serial L6C20 as well is tuned to 1900- kHz. Double triode VT5 works as regenerative detector (left triode) and Audio amplifier (right triode). L5C18C19 should be have high Q, so, coiled by quality copper wire and C18 and C19 should be air- gap capacitors. R14- RF Gain, R6- regeneration level.

Parts: For Data for inductors see Table 1. All resistors may have tolerance 30%. Wide range of tubes may be used at the radio- station. Any low power pentode may be used for VFO. Any pentode that can give out 5-10 Wtts may be used at PA. Tetrode as well may be used for PA. In that case RX input connected through capacitor in 10-pF to anode of VT7, contact K1.1 of relay K1 is connected to bridge with L7C23 (so at TX mode the input is shortened to the ground).

Table 2 Inductors Data of the Radio Station

http://www.antentop.org/

Page 74