Needed: Help with HRO Coil Adjustment (SOLVED!)

[ashart]

I'm beginning to work on GC alignment of an HRO-60, and everything is OK at the top end of the B coil. But, the sensitivity is lower at the low end of the band and slight bending of the tuning cap plates shows poor low-end tracking.

I don't understand how to physically adjust the coils at the low end of the bands.  

Some of the coils have loops of wire to be bent and some have disks to be moved, but looking through the tiny holes on the back of the coil cans, I don't see how to do the adjustments.

Any ideas around on good ways to bend loops, move discs, and check the results of the changes?


In an old HRO manual, correct date unknown, but was priced at 10 cents (!) and indicated a 1939 copyright, I discovered a couple of drawings that clearly show the adjustment methods.  Thus, my problem is solved, but if anybody would like an emailed copy of that manual, let me know and I'll send it along.  I acquired it somewhere on the internet, but I'll never remember where.

73 de al hart


-al hart, w8vr

[Jim, W5JO]

Check, unplug, make adjustments, plug back in, recheck....continue until correct.

[ashart]

Hi, Jim -

Yeah, I assumed that it would be tedious.

Do you know how to bend the loops and move the disks?

-al hart

[WQ9E]

Al,

I made a little notched wooden tool for the loops (also found in other National receivers).  Be gentle with the loops as they will break if moved excessively.

[ashart]

Rodger:

A "special tool" is a good idea!

Do you know which way to move the loops to increase L or to decrease it, or does one just learn by experimenting?  Are they all the same?

Do you know how to move the disks?

-al h

[KM1H]

Spring hook.

If you follow the manual it should work.

I hope this wont be the start of a new thread for every question...its getting annoying.

Carl
KM1H
National Radio 1963-69
Service Tech/Service Manager

[ashart]

Hello, Carl -

Carl, there have been other negative comments about the number of questions that I've posted.

It's certainly not my intention to irritate anybody, especially those who are so generously helping me.  To those I've irritated, I apologize.

But I don't know how to deal with the problem.  Because of my inexperience at restoring gear, I don't seem to become aware of my need for information on some matters until I've concluded other matters, so I can't forsee some of the questions.

For example, I've most recently posted a question dealing with the front-end alignment of the receiver.  Yet, I didn't get to dealing with the front-end alignment matters until I had resolved a bunch of other questions that allowed me to work my way toward the alignment tasks.

I sure don't want to become a nuisance here, but my enjoyable journey through the HRO has already taken some weeks, and will probably take a few more.  Today, I have no clue as to what problems I'll encounter next week, on which I may need help from the forum.

I'm wide open to any constructive ideas that you, or any other members, may have.

73 de al hart, w8vr

[Jim, W5JO]

Al, you are asking questions that an experienced National tech would consider boring.  With my first HRO 60 I looked and decided what to do.  I posted that in my first answer.  As to the direction of moving the loop, if you move the wrong way the tracking will be worse.

As for what kind of tool to move the loop, it really doesn't matter because you have the coil unplugged so the material of the tool is not an issue.  I use a stainless steel pick bought from Mac Tools.  You can use anything that fits the hole.

Just remember with coils it doesn't take a lot of movement to change the inductance a lot which will throw the tracking way off in mid band if you move too much or in the wrong direction.  You may have a lot of fun if you have 4 coils, I had nine.  It did take a while, but worth it when I finished.

[W3GMS]

Hello, Carl -

Carl, there have been other negative comments about the number of questions that I've posted.

It's certainly not my intention to irritate anybody, especially those who are so generously helping me.  To those I've irritated, I apologize.

But I don't know how to deal with the problem.  Because of my inexperience at restoring gear, I don't seem to become aware of my need for information on some matters until I've concluded other matters, so I can't forsee some of the questions.

For example, I've most recently posted a question dealing with the front-end alignment of the receiver.  Yet, I didn't get to dealing with the front-end alignment matters until I had resolved a bunch of other questions that allowed me to work my way toward the alignment tasks.

I sure don't want to become a nuisance here, but my enjoyable journey through the HRO has already taken some weeks, and will probably take a few more.  Today, I have no clue as to what problems I'll encounter next week, on which I may need help from the forum.

I'm wide open to any constructive ideas that you, or any other members, may have.

73 de al hart, w8vr

Al,

Your postings have not bothered me at all.   Since you have covered a lot of ground while your learning, the separate post are almost like chapters in a book. 

Your questions have benefit many in those that read and seldom post are learning along with you by reading your questions and the post.  Some op's just go in and replace a few caps and resistors and it plays and they stop there.  Your taking a few extra steps in trying to totally optimize your 60 as well as understanding how everything works.  Not a bad way to go in my book! 

I know your enjoying learning a lot about your HRO-60.  As you have noted and given credit to many, this site has some of the best talent and experience around.  Some just have a different delivery style!   You have no need to apologize to anyone. 

Keep the questions coming and enjoy working on your HRO-60. 

Regards,
Joe, W3GMS
 

[k4kyv]

Those are very appropriate questions.  I acquired my first HRO in the late 60s and had nothing to go by except for the factory manual. Many, if not most, of those who acquire a similar receiver to-day would be told that the manual was long lost. Luckily, a usable copy can probably be downloaded easily enough off the internet.

Mine was the original HRO, circa 1935.  But you would be astounded how little the basic design of the receiver was changed over the years, all the way through to the last of the HRO-60s.  The layout is practically identical on all versions, and the power supply is actually a separate chassis bolted onto the main chassis, which is virtually identical to the original that used on outboard power supply (aka "doghouse").  Yes, they went to more modern tubes, and added the noise limiter and a few other bells and whistles, and added the slide-rule dial to replace the tuning charts. The HRO-60 is dual conversion above 40m. But all models of the receivers are still basically identical. I have even used coils salvaged from the HRO-50 plug-in module to resurrect a pre-War model. That says a lot for a design from the early to mid 30s to change so little over a period of nearly three decades.

What better way is there to learn about your receiver than to pick the brains of those who are familiar with them because they have actually used and maintained them over the decades?

[W7TFO]

Some people are never happy unless they are annoyed.  

If one does succeed in making them truly unhappy, they are virtually ecstatic.

Lessons learned from a previous (lab experiment) wife.

73DG

[ke7trp]

Al.  Keep up the good work and post all you want. Its a forum. Thats what it is here for. There are alot of helpfull poeple around.  Just ignore the flack.

C

[w3jn]

Al, the questions are not in the least annoying.  As Clark said, that's what the forum is here for.

However, as I pointed out in one of the half-dozen or so threads you have going on this receiver, it's best to post one thread for each project.  As an example, one of Tom K1JJ's transmitter projects ran 8 or 9 pages.  If he posted a new thread for each question he had, it would have amounted to a couple dozen threads, all scattered around, and it would have been impossible to follow the progress of the project.

[KM1H]

I also replied then that I agreed with John who also happens to be one of the forum moderators. I would have thought you would have respected his simple suggestion.

Ive nothing against any of your questions, just the way they are scattered to hell and back which makes it too annoying to look to see if Thread 1 and Thread XX have a common point that could be related to a problem. For that reason I havent replied much.

Carl