More on the Drake 2-B from Steve KW4H -- Part 2 -- Recapping. Cleaning Tubes and Sockets. Tube Tester

The recap is finished.  You can see the new Hayseed Hamfest cap on the chassis, as well as the other new caps.  In these receivers, I also replace every old paper cap -- even the ones in the so-called "hard to get to" places.  On the Drakes, you have to work sideways as many of these boards are vertically mounted.  Drake did that to save space and give their gear a smaller footprint.  The tradeoff is the workbench gymnastics.

The 2-B now has a brand new, 3-wire power cord.  The old bypass caps on the AC line were removed, and a new ceramic safety cap installed on the hot line, between the bottom of the fuse holder and ground.  The original purpose of these capacitors was to filter out household AC line noise.  Such things are rarer these days as household appliances are better designed, but for completeness purposes I think a safety cap on the hot line is reasonable.  

All the tubes were tested and substitutions made where needed.  A word about tube testers:  they're good for discovering major faults, but IMO the best tube tester is the circuit it was designed to run in.  So for these tests I'm just looking for shorts, gas leaks, and obviously weak tubes.  

In addition to testing the tubes, each tube socket is cleaned with a disposable interdental cleaner dipped in 99 percent isopropyl.  Following this, the tube pins are lightly brushed with DeOxit D-100L on the end of a q-tip.  All it takes is just a light film.

The 2-B powered up!  We have contact -- and, of course, some other issues to deal with.  The preselector capacitor was noisy -- the cover was pulled off and it was sprayed and brushed to remove any "whiskers" or other contamination that might cause unwanted conduction between the plates.  It's better now, but I'll keep an eye on it throughout the rest of the process.

Since the passband tuner had to be removed and repaired, it's clear from the sound of things that the passband tuner badly needs to be realigned.  That's going to be done next -- as long as we can jam a signal through the receiver, it's best to realign the passband tuner before swinging around and running through the overall alignment process because it has such a profound effect on the audio and signals.  Also, aligning the passband tuner is logistically more complicated than in Drake's 4-line, as two of the slugs aren't easily accessible.  I'll send some photos later showing how we get around that problem.