Sunday, August 13, 2017

Giving New Life to an All American Five - Part 1.

I have a weakness for old radios.  I don't know how many I have - easily more than 100 - but I still don't consider myself a collector because I don't have the desire to accumulate specific makes or models.  Nope.  I just like working on them and, when something interesting comes up at the right price, I have a hard time walking away.

Earlier today, my wife and I met friends Sean, WX8L and Jeff, KF8XO and their wives Andrea and Karen for a trip up to Port Huron where there was a ham radio "trunk sale" being held along the shore (seawall, actually) of the St. Clair River.  While it wasn't a "full blown" hamfest, there were some cool items, including several boat anchors, being offered up for sale at reasonable prices.

While I was able to resist the siren song of the R-390A (already have one), NC-300 (Wife would kill me) and Mosley CM-1 (that one was tough to resist), I couldn't pass up the grimy little Silvertone 7054-J with the $12 price tag, especially when the seller said I could have it for $10.

For whatever reason, this little set "spoke to me", so while I'm pondering on my next homebrew project, bringing this fellow back from the dead will give me something to keep myself busy (and keep this blog active.)  

So, where do you start on something like this?  I like to start by cleaning the heavy dust and crud from the chassis, and, as you can see above, this set had more than it's fair share.  I'm not out to detail the chassis - just get it to where it's not as gross to work on.  a few minutes with a semi-firm bristle brush makes a big difference:

While cleaning, I noticed that the #47 dial lamp was open, so I replaced it.  Low hanging fruit; one less thing to deal with later.

This set has push-button presets that operate mechanically, and, as you'd expect, the mechanism was gummed-up with 70 year old grease.  Another low-hanging fruit: cleaned, adjusted and re-lubed the mechanism, including the tuning capacitor. 

The most common failure item in old radios is not, as most people assume, the tubes.  Nope, it's the capacitors.  In a radio this age, it's a virtual certainty that the electrolytic capacitors in the power supply will be shot, so I checked the value of the originals and made sure I had suitable replacements on-hand.  

The "can" in the above picture contains the aforementioned power supply caps - it's a "three-in-one" affair: The can contains two 40 uF, 150 volt caps and a 20 uF, 25 volt cap.  Pretty typical - what I'll do is "restuff" this can with modern replacements (47 uF/160V and 20 uF/35V.)  You can usually go a bit higher in capacitance (within reason) and can always go higher in working volts, and those will be fine replacements.

But, it's 2300 hours and I'm not going to get into that tonight.

73 - Steve N8NM

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