Manufactured in Riga, Latvia, VEF

(my receiver was made on 1979)

Super-Heterodyne receiver

( only 10 semiconductor transistors) have LW and some SW broadcast band.

I added 19m and 17m bands.

(easy for this receivers, you need only free band-plate for make new band).

I have made also CW local oscillator (LO) in IF frequency 465 kHz. This LO mast be set near IF amplifier and receiver modification to enable them as CW/SSB-reception.

LW: 150 - 415 kHz (2000 - 723 ì)
SW: 520 - 1600 kHz (577 - 187.5 ì)
HF1: 3.95 - 4.85 MHz (75.9 - 61.9 ì)
HF2: 4.85 - 5.9 MHz (61.9 - 50.8 ì)
HF3: 5.9 - 6.2 MHz (50.8 - 48.4)
HF4: 7.1 - 7.35 MHz (42.2 - 40.8 ì)
HF5: 9.5 - 9.8 MHz (31.6 - 30.6 ì)
HF6: 11.7 - 12.1 MHz (25.6 - 24.8 ì)
VHF: 65.8 - 73.0 MHz
(IF ÀÌ = 465 kHz, IF VHF =10.7 MHz)

Riga-104 have better sensivity than VEF-202

Good audio ! But worse bandselector and problems repairable.

Repairing old potentiometers

 The change of original components when restoring old radio or transceiver sets is always an unpleasant. In the case of potentiometers it is difficult to find double original potentiometers for RF/AF or Mic/RF PWR.

 If you hear rustling in old potentiometers of your old transceivers you need repair them with oil. My practice is to use syringe with solid oil + spirit. Usually I use russian solid oil ÖÈÀÒÈÌ-203 (ÃÎÑÒ8773-73) . You can use SIMNIA 0, PETROLEUM JELLY S68OO,Mobiltemp SHC 100, AEROSHELL 15A or good quality machine oil.

 You don`t must to open potentiometers, you must only press out some oil with spirit into potentiometers. You must to turn the potentiometer minimum 20 times from end to end. The solid oil hits to center contact and will protect contact near axis.
 This technique is very effective and, usually, these potentiometers will still perfectly efficient. But i know what in 5% of cases where the resistive surface has been damaged and way with repair potentiometer by oil does`t work.

If you need new anti log and log potentiometer- let see figure below and change your old part to new 500k Ohm...1M Ohm potentiometer and adding resistor R2.

Getting from : Electronic Instruments, MIT Radiation Lab Series, Vol. 21

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