266
Item nr.


Sigma Rekord Table top

TRF radio with just one tuning circuit.


Data for Sigma Rekord
ProductionCzechoslovakia, 1939.
BandsLW, MW, SW.
Tubes1801, AF7, AL4.
CabinetWood. Size 44x25x18cm.
PowerAC (110-220V).
DocumentsSchema (thanks to Martin Hajek).

The Design

Regenerative receivers were state of the art in the twenties, but became obsolete soon after the introduction of radios with frequency change. This radio, built just before World War Two and regenerative, is a very late example of this type of receiver. It is not so easy to operate; this requires some technical skills and knowledge. One should be careful not to let the receiver generate too long, as this may waste the neighbor's listening pleasure (Mexican dog).

Obtained10/2005 from Bazar Plzen.
Condition6.
DisposedSold 10/2013.
Sound samplePLAY SOUND   When I was in Czechia, I often listened to the Dutch station on 1008kHz at night. In the evening, this old Czech machine will bring the sounds from its country to my own home in The Netherlands, a distance of about 1000km. You hear the opening of Ma vlast by Smetanach.

This Object

The schema of this radio shows a B443S output tube (directly heated) but the radio actually is fitted with an AL4 (indirectly heated). I do not know if this was just a later version, or that the radio was modified. I do know that there were different versions: this design, with the four-pointed star-like wave switch is factory original, though some Rekords have another type of wave switch. A reason for changing the output tube could be the replacement of the power transformer. This part certainly is not original, and the replacement transformer does not have a center tap on the second 4V winding. This is difficult for a directly heated tube.

The chassis layout printed on the back panel (left) shows a power transformer mounted on the chassis. No output transformer is anywhere in sight on this picture, so I presume that originally the radio had an output transformer mounted on the loudspeaker. Anyway, in actual fact, the radio now has a modern power transformer next to the chassis, and an output transformer on the chassis.

The radio works, if this could ever be the right term for a TRF regenerative receiver. Hearing a radio station is a constant twiddle with the tuning and regen buttons. Also, a fairly long antenna is needed.


Part of Gerard's Radio Corner.
Generated by SiteBuilder on 26/2/2024 by Gerard (g.tel@uu.nl)