RUSS' OLD RADIOS
  • HOME
  • FOR SALE
    • CURRENTLY AVAILABLE
    • DO IT YOURSELF SPECIALS
    • EXCEPTIONAL DEALS
    • WITH MP3 PORTS
  • RESTORATION
  • BLOG
  • BEFORE/AFTER
  • CONTACT US
  • UNIQUE RADIOS
  • 1920'S Superheterodyne

The Strat is Alive

6/10/2017

1 Comment

 
Well I couldn't wait for the tubes to get here, so I substituted some used ones in both chassis and began testing. It WORKED on the first try. Yeah, even I would not have bet on that but I'll take it.


Picture
My bench is not all that large so it take a few additional carts and such to hold all of the parts.

I did not get off with no issues though. Actually there were two.

Below you see the control/signal cable that runs between the chassis. There are three conductors that carry line voltage. Depending on the plug polarity (it is not polarized) and whether the set is on or off 120V can be on any - or 2 of the three wires. These 3 wires are twisted within the armored cable. Over years of rubbing and becoming brittle, there were many abrasions on these wires. The result could have been a short but what I saw was 120V AC on the chassis intermittently.

I knew that this cable was a problem. I had hoped that some repair to the end was going to suffice since an exact reproduction was going to be hard to produce. But now I have given into that reality.

Picture
The other issue was less significant. In the comments on the earlier Strat post below John mentioned a problem with the "Q" relay not working. Well this one - the one I rewound - didn't work either. So -

I resisted the urge to take it apart and rather measured the source voltage. It was around 300V with a short warm-up. I measured the connection to the plates of the 85 tube. It was at around 280V. So I had continuity across the relay coil and an expected voltage drop meaning that the 85 was conducting.

I then checked the grid voltage generated by the AVC tube. Something close to 0 volts allows the 85 to conduct. A signal as high as 10V will switch the 85 off, deenergising the relay. I was seeing from -.4V to about -7V. So my AVC signal was good. (when the relay is energized the closure shorts the secondary of the high frequency interstage transformer which mutes the audio until another strong signal is tuned).

So what was the issue? Checking the less than deluxe relay (see pictures in the earlier post) I found that a little nudge closed the relay. The simple solutions would be to lessen the spring tension or move the stop so that the magnetic coil was closer to the throw. I chose the latter approach and all was well.


Below is a short video after alignment. The radio is only on a short antenna so short wave reception is limited. However, when I switched on the upper band I did receive several stations, WWV and even CB transmissions. This is notable since the oscillator section of this receiver is a bit challenged above 22mhz. So I was pleased.
So this concludes the chassis restoration. Once the NIB tubes arrive (42, 5Z3 and 45s) the chassis will be reinstalled into the cabinet.

Since this project was a trade, labor less parts for a unrestored McMurdo Silver Masterpiece V, I had declined the cabinet work, instead preferring to do the fun part. The cabinet was refinished by a friend, Gary, who lives a bit north of here. The cabinet is finished, but I have only seen pictures, so far. Probably within the next two weeks you can expect to see pictures of the reassembled 1000Z.

While this project was running I was also restoring  the MPV. It is also finished - a very impressive 20 tube radio in itself. When I get some time I will post some pictures of it in the next blog.

Russ
1 Comment
Harry
6/13/2017 07:08:37 pm

Super nice restoration Russ. Jeff should be extremely happy with your work.

Reply



Leave a Reply.

    Author

                         Russ Webb

    Picture
    Russ Webb & Fuzzy

    Best Buddy, Radio fixer







    Categories

    All
    All
    Antiques
    Electronics
    Radios
    Repair
    Restoration
    Travels
    Vintage

    RSS Feed

    Archives

    March 2023
    November 2022
    October 2022
    July 2022
    January 2022
    December 2021
    September 2021
    June 2021
    April 2021
    February 2021
    January 2021
    November 2020
    July 2020
    June 2020
    April 2020
    March 2020
    December 2019
    October 2019
    May 2019
    April 2019
    March 2019
    February 2019
    January 2019
    December 2018
    November 2018
    October 2018
    September 2018
    June 2018
    April 2018
    March 2018
    February 2018
    January 2018
    December 2017
    November 2017
    September 2017
    June 2017
    May 2017
    April 2017
    February 2017
    December 2016
    November 2016
    October 2016
    September 2016
    August 2016
    July 2016
    June 2016
    May 2016
    April 2016
    March 2016
    February 2016
    January 2016
    December 2015
    November 2015
    August 2015
    June 2015
    May 2015
    April 2015
    March 2015
    February 2015
    January 2015
    December 2014
    November 2014
    October 2014
    September 2014
    August 2014
    July 2014
    June 2014
    May 2014
    April 2014
    March 2014
    February 2014
    January 2014
    December 2013

CUSTOM DESIGN BY SUE WEBB  06/2013       Redesigned by Russ Webb     Approved by Fuzzy   Updated:  Pretty much all the time, but I forget to change this date
Proudly powered by Weebly
Photos used under Creative Commons from valart2008, rafeejewell