The HW-101 Saga: Ch 312

[K7SZ]

When we last saw Tricky Dicky, ace electronics technician, he was elbow deep inside the HW-101 trying to sort out an oscillation problem in the receiver. 

SUCCESS!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

I didn't want to keep boring everyone on this list so I had several private e-mail exchanges with Ken Gordon, W7EKB and Mark Graalman, WB8JKR, regarding the various things I had done and the cumulative results. Thanks to their combined inputs we managed to solve the weird oscillation and get the receiver back to working status.

Believe it or not, the main problem stemmed from gunked up tube sockets! That's right....mung had accumulated in the base of the three tube sockets on the IF board and were causing some really weird things to happen. Additionally, we found this gooey crap on other sockets and have taken appropriate actions.

We swapped out the three IF board sockets with sockets from the HW-101 parts rig...these sockets had center pin ground connections (they were the early versions of the tube sockets that Heath originally used on the rigs) and they all had a pin to ground a tube sheild (although the manual doesn't call for shields on these three tubes, we installed them, none the less as a precaution). 

Let's digress: originally this set was given to me about a year or so ago. It was cosmetically in very good condition, which is why we decided to undertake the restoration. 

The inside of the chassis was covered with a thick film of some sort. Not sure whether it was cooking grease, coupled with nicotine and tar, or whatever. It was a mess. So we decided to take some alcohol and clean up the upper and lower PC boards and chassis, using long cotton swabs, t-shirt material cut into small patches, and a toothbrush. 

During the "clean-up" process, small amounts of cotton fiber from the swabs and from the t-shirt material got under the sockets. This, coupled with the alcohol AND a liberal application of DeOxit D-5 spray caused some conducting paths to be established that didn't exist on the original boards. Ergo, we ended up with an oscillation that we spent a WHOLE bunch of time trying to find and quench. 

Replacing the sockets did the trick. Additionally, we tried changing out the 8-50pf trimmer on the Xtal cal oscillator along with the actual 100 kc xtal. This was a very BAD idea as the replacement xtal (from the parts rig) didn't oscillate and we thought that we had an additional problem of no osc output when in the cal mode. Luckily, this was the last thing we did after replacing the sockets, so it was a simple matter to go in and check for plate voltage on V-17, then check the output of the osc with a counter....nothing....hmmmm.....chk the xtal....BINGO. Replace xtal. Now we had a xtal oscillator again. 

We went back through the entire alignment process on the receiver and everything...EVERYTHING, is now within specs and works as them manual dictates. (Folks, this is a REAL Prozac moment!!)

So, now we are at the TX tune up portion of the alignment. This will be postponed until I can get to N3WWL's house and we can use one of his Monitor scopes and a 100 watt dummy load to properly adjust the transmitter and neutralize the finals. We don't have this test gear at work

In the mean time, we are now doing the majority of the mods that Mark outlines in his well detailed modification data sheets. 

So, with any amount of perverse luck, the HW-101 should be on the air this weekend, or at the latest, next weekend from K7SZ. I'm looking forward to using it this winter, now that it performs as good as it looks. 

Thanks to all of you who've offered suggestions and morale support. A special "THANK YOU" to Ken and Mark for their in-depth analysis of my troubleshooting journey and their insight to the problems. Guys, I could not have gotten this rig up and running without your help. 

One other thing: We have drawn the conclusion that a full restoration of any Heathkit (or other kit rig) should include stripping the parts off the PC boards, right down to bare board, thoroughly cleaning the boards and then basically rebuilding the kit using the manual as a guide. This sounds like a lot of work and it is. However, the time that we wasted chasing phantom problems that were caused by our own eagerness to "do the job right" amounted to much more time than stripping and rebuilding the boards would have taken. 

Now there is a difference between "restoring" and just getting the rig up and running to work. As far as we are concerned, if a restoration is in order, then you need to be prepared to do the "full Monte" and preclude a bunch of problems like we encountered. 

73  Rich K7SZ

Editor, "QRP POWER" (QST)
Editor, "Homeland Security"  (Popular Communications)

QRP ARCI #2388  NorCal # 483, G-QRP-Club # 622, EPA-QRP # 21,
NW QRP #24, Zombie # 664, Ten-10 # 39647, FISTS# 2793
Flying Pigs #169, Shoes: 13 W, Jock: XXL, Grid: FN21bf
Aficionado of all things Drake and Heathkit

-----------------------------------------------------------
This list is a public service of the City of Tempe, Arizona
-----------------------------------------------------------

Subscription control - http://www.tempe.gov/lists/control.asp?list=HEATH
To post - HEATH at LISTSERV.TEMPE.GOV
Archives - http://interactive.tempe.gov/archives/HEATH.html