Saturday, December 12, 2009

restoration of an Olympic Model 6-606, a 1946 portable tube radio

As of last weekend i have started the restoration of a portable tube
radio, it is an Olympic Model 6-606. This radio was built in 1946.
It is cable of running off either batteries (two type B 45 V
batteries and two type A 4.5 V batteries) or line voltage.

So far, most of the wax and paper capacitors have been replaced and
most of the electrolytic capacitors.

Waiting on some mail order parts, including a new leather handle and
a high voltage electrolytic.

More to come later..... Stay tuned!


  1. Absolutely amazing project! I've tried to restore nearly the same VEF receiver (made in Riga, 1949), but wooden parts was completely broken by insects and I've decided to use that Radio as a spare parts. So sorry. My compliments, Gregory!

  2. Yeah, the wood on this radio is really dry too! I'm surprised it held up. If the wood was rotted i would have scrapped this radio too, i understand.

    One strange thing about this radio is the power cord. It has 3 wires, 2 for lines voltage and the third is a nichrome wire that creates a 540 ohm resistance for stepping down the line voltage to power the rectifier tube filament. This wire dissipates 12 watts of power. I had to replace this with a few high power resistors. These resistors get really warm. So, running this thing off line will be a little tricky. I might have to retrofit a heat sink onto this radio just to cool the resistors,...

  3. Very interesting about that long and flexible resistor. Yes, it has been made for a good heat dissipation, sure, but it is first time ever when I hear about such interesting solution. Maybe it should be better to save an original cord?

  4. Yes, you are right, i want to use the original cord. When i examined the cord i found that the insulation on the wires had dried out and cracking. So the cord was no longer usable. The 12 w of power dissipated by the cord probably heated up the wires inside of it too much over the years.

    The 540 ohm resistor that makes up the cord is used for powering the filament in the rectifier tube. The filaments of all other tubes in the radio are powered off of this rectifier too. So there is really no reason to have a tube rectifier. So i replaced the tube rectifier with a diode. I no longer need the 540 ohms of resistance, dissipating 12 watts of heat inside of my radio or on the power cord. So that makes life easier.

    Got the radio going last night. It sounded really distorted. So i am looking into this issue. It sounds like there is clipping in the RF stages somewhere.

  5. O'k, Gregory, I can imagine this filament circuit - all heaters in serial except the rectifier's one. So, your solution is an optimal compromise (I'm not purist ;). Good luck with distortions fighting!

  6. Hello,
    I saw your post on the ARF board.
    You know, there is another way to drop the voltage other than a resistor.
    Using a non polarized capacitor you can indeed drop the voltage, and not have any heat buildup as you would using resistors. This page, (Scroll to the bottom) had a spreadsheet you can download, and you can calculate what size of capacitor to use. It also shows other combinations to drop the voltage for your set.

    Good luck!