Grundig 3097
Katrine Freggiaro
I dont collect them with a certain strategy. The radios find their place here by coincidence because I cant help taking care of the worn, non-working sets and give them new life and a good home. The fun part is troubleshooting and tuning-up as well as finding the parts needed in my junkbox. The restored radios which have no given place in my rooms are presently piled in the wardrobe or the garage.
Antique radios don't appeal to me as much as those from the 1950s. People who fancy old things often have an emotional relation to them, perhaps as memories of their childhood. Magic eye, gold-gleaming speaker cloth, lots of geographical names on the well-lit dial glass, brass edgings, white pushbuttons, everything enclosed with polished hardwood, it was that kind of radio that I had a yearning for when I was a boy. The manufacturers brochures boasted with the number of tubes, the more the better of course. As I had started with dx-ing I preferred radios with more than one shortwave band and on the 80 m band were AM-transmissions from Swedish radio amateurs. In spite of all this my first radio turned out to be an old set.
A Marconiphone 853 alias H.M.V. 657 from 1938 was bought at an auction for 5 kr (my weekly pocket money) in the late fifties. It has LW-, MW- and two SW-bands (13-30 and 30-90 m), tuned RF-stage, magic eye and motor-driven tuning capacitor with buttons for eight preset favourite stations on LW and MW. A circular logging scale facilitates tuning and it is driven together with the dial rod by a thin wire so there is no need to change a cord. The band indicator is driven by a chain from the switch. The dial.
The tubes are Marconis equivalents to American octal tubes: KTW63, X65, KTW63, DH63, KT63, Y63, U50. KTW63 have fixed screen voltage although they are beam tubes, the limited dynamic range of the magic eye required a low AGC-voltage. The electrodynamic loudspeaker is big with 62 Hz resonance frequency, but there is no negative feedback in the power amplifier. Output power is 2 W at the onset of clipping and the frequency response of the AF-amplifier is 40 Hz-6.5 kHz at -3 dB. This was a great receiver for its time, but a design mistake is that the oscillator tuned circuit is on the grid side rather than on the plate side which detoriates frequency stability on shortwave. However, this was done on recommendation from the tube manufacturer. The price in England was 39 guineas and in Sweden 460 kr.
I have replaced electrolytic and paper capacitors, five tubes are original ones but the magic eye is now UM4. As mixer tube 6J8G will work but not ECH35. Because I don't care for museum condition but want to use my sets, I have put a PCIM177 frequency readout behind the glass, zener-stabilized the voltage to the oscillator and replaced the tone control capacitor with an antenna switch. I can on the SW-bands select either the original high-impedance antenna connector (10 pF capacitive coupling to the control grid) or a low impedance connector coupled to a broadband transformer 1:9. The sensitivity varies between 3-9 V. An S-meter has been placed behind the glass to the left of the magic eye (not visible on the photo).
In the beginning of the 1960s I mostly listened to the pirate station Radio Nord with it, but later in the 1980s I used the radio for renewed dx-ing during a couple of years. It was then I added the digital display which for the first time let me know where I was listening. The latest improvement is addition of a detector for SSB/CW, for a steady tone it became necessary to replace the mixers AGC with a fixed negative voltage when the detector is in use.
When I started with amateur radio it was with telegraphy and I needed a beat oscillator. As such I borrowed the family radio which besides LW, MW and UKV also had two SW-bands, 16-55 and 55-180 m, and whose tuning could be chosen so that the local oscillator interfered with the Marconi set to give the necessary beat note. This Swedish Kungsradio 755 UKV from Gteborg, of 1955 vintage, became my gateway to the dx-hobby. It was in daily use until the year of 2002 and still works reliably after changing of tubes, capacitors and dial lamps. I have replaced the selenium rectifier with silicon diodes, added a mains voltage fuse, separated the connected screen grids of the mixer and IF-tubes and added trimming capacitors to the SW antenna circuits.
The tubes are ECC85, ECH81, EF85, EABC80, EL84, EM34. Sensitivity is 4-8 V on the SW1-band which is most suited for a low impedance antenna, the inductance of the antenna coupling coil is 0,25 H on SW1, 200 H on SW2, 1.5 mH on MW and 12 mH on LW. There is no ferrite antenna and the tone control is a simple treble suppressor. The loudspeaker (Philips 9768 with 68 Hz resonance frequency) is half-hidden behind the dial glass, but in spite of that the audio quality is good. The internal loudspeaker can be switched off when an external one is used. The frequency-independant negative feedback is supplied to the cathode of the power tube, with my increased plate voltage the output power is 2.6 W at the onset of clipping and the frequency range is 36 Hz-28 kHz at -3 dB, so I have doubled the value of the limiting capacitor connected to the plate of the AF preamplifier. The rotary band switch was out of fashion when this set was made, most radios had pushbuttons. The price on sale was 300 kr, reduced because the radio was old stock. The dial.
Philips B2X63U "Philetta" made in the Netherlands in 1956 became very popular as supplementary radio after the introduction of a second radio channel on the UKV-band because it was cheap and needed little space and there was often a bigger radio in the household. With improved housing conditions it also found its way into the teenage room. It is an AC/DC-set, both because there were many places with DC-mains even in the 1960s and a transformer would make the radio bigger and more expensive. In spite of its compact size 19x17 cm the reception capability is as good as that of bigger radios, there are just as many tubes and circuits and the audio power (1.5 W at the onset of clipping) is enough, but everything is compressed and the components are placed in layers below the chassis. The few capacitors that need to be replaced are easily reached, however. The cabinet is made of plastic and on the front there is a plastic piece with dial and vertical ribbons in front of the loudspeaker net. It is lighted from beneath by two lamps and it gives the radio a pleasant appearance in a dark room. For MW and LW there is a built-in ferrite rod but for UKV an external antenna is required. Even a SW-band is included but limited to 23-51 m and it has no other markings than the four broadcast segments. There are separate knobs for UKV- and AM-bands and behind the loudness type of volume control there is a treble-cutting tone control.
The tubes are UCC85, UCH81, UF89, UABC80, UL84, UY85. I replaced the mixer tube and four capacitors, put in a new temperature fuse and increased the value of the run down filter capacitor with 33 uF in parallel. The SW-band needed a change of two capacitors in the antenna circuit for full sensitivity and after that it measures 4 V for 50 mW output power at 10 MHz. With regard to input power to the UL84 the AF output should be twice as high, the low efficiency probably depends on a compromise in impedance matching to make the radio usable with 127 V mains, but with connection to external loudspeaker the sound is rich enough. I did not expect this sort of radio to end up in my collection but it is better than I had anticipated and it was free in the scrap container.
Found at a scrap-yard was this Swedish Centrum 261 from 1958, it was made by Gylling & Co in Stockholm and the original price was 495 kr. Besides LW, MW and UKV it has two SW-bands, 18-50 and 55-185 m. The UKV-knob gives bandspread on the high frequency SW-band. The radio has "3D-sound" using three loudspeakers, an oval 4 ohm Isophon P1521, 19x13 cm with 100 Hz resonance frequency, and on each side a 5 cm Voxtone tweeter (18 ohm and 1 kHz resonance frequency) which can be switched off with one button and the red button turns off all three, a useful gadget for anyone using a magnetic loop for hearing aid or had an external loudspeaker cabinet. Such is recommended because bass reproduction of the main speaker is not good enough and worse than that of Granada or Truxa below. The tone control attenuates treble with 4 dB while four small buttons select fixed registers, Orchestra-Opera-Solo-Jazz. The power output is 2.2 W at the onset of clipping.
The register buttons were a whim of fashion, separate controls for bass and treble would be more useful. Without any pressed button the sound is suitable for speech with +3 dB at 3 kHz, -3 dB at 560 Hz and -6 dB at 300 Hz. Solo has the same treble response, 9 kHz at -3 dB and 11 kHz at -6 dB, but reproduces more of the medium range. Jazz enhances high tones, Orkester have the same treble response but gives more bass with 120 Hz at -3 dB and 65 Hz at -6 dB. Opera lies something between them at frequencies below 1 kHz. All figures relate to 1 kHz.
The tubes are ECC85, ECH81, EF89, EABC80, EL84, EM84. The radio lacks a ferrite antenna for LW and MW but can use a UKV-antenna for the AM-bands. The sensitivity is 6-12 V on SW. The inductance of the antenna coupling coil is 0.7 H on SW2, 3 H on SW1, 12.8 mH on MW and 24 mH on LW. I have changed electrolytic and paper capacitors, dial lamps and three of the tubes and I inserted a mains fuse. The selenium rectifier is replaced with silicon diodes and a 9 kHz trap across the output transformer is removed because its frequency had decreased to 8 kHz. The chassis has holes punched for a second IF-stage, an ambitious technician who finds suitable IF-transformers can improve the sensitivity. On the back is a connector for external volume control using screened cables. It is unusual to find names of Swedish stations on an FM-band dial but here they are.
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