This time, I don't know HOW I did it.
Everything was working well, the receiver was properly muted and dow key had switched over to the transmitter. I had just had a short, and not very strong QSO, on 7200+/- 2kc. Shortly after the QSO, I smelled that familiar smell, of something electrical burning. It did not seem to be losing sensitivity, but I was NOT taking any chances, so, I turned it off, and immediately unplugged it. After a short time sulking, over wiping out something, I decided to try to dig into it.
Well, I found a fried antenna coil, and I do not believe it was even the one covering 5.7-10mc band spread. It might be, but I don't think so. Radio is a Hammarlund HQ 150. Here's some photos of the coil itself. In the third one, you can see where the inside of the coil was bubbling from the heat, when they burned.
Attachment 95685Attachment 95686Attachment 95687Attachment 95688Attachment 95688Attachment 95689
I am trying to figure out how to remove it, and see if I can rebuild it. Then try to track down WHY it burned. But I wonder if the last couple of photos might have something to do with it.
Suggestions for how to remove the coil, for rebuilding?
Anyone familiar with this procedure, lend a guy a hand, to keep it off the "Parts Radio" bench, or for sale as a parts rig? I am a newcomer to trying to fix stuff, myself, but I don't like the idea of scrapping something, over ONE part. But, it may be too difficult to find, or rebuild. What's the score, folks?
Sounds like you DowKey relay is not properly switching. The spacing between the contacts is adjustable and, probably, either the transmit side is too close or the receive side is too close. To adjust the spacing you just loosen the "nut" on the UHF connector on either side and then rotate the connector counter-clockwise. You can see these contacts by removing the "plug" in the end of the relay.
Also, it is possible that the moving vane is not completely horizontal. This is adjusted by loosening the "nut" on the "antenna" connection and slightly rotating the connector until the vane is horizontal.
Rewinding the coil is not difficult. You just have to use the same gauge wire and put on the same number of turns. I have repaired a number of receivers, over the years, that have had r.f. run into the antenna circuit.
Also, make sure that the coil of the relay is releasing fast enough. Over time, especially those relays with AC coils, get "lazy" and it takes longer for the relay to return to the receive side.
Somehow, I was sure you would be the first, to help, or one of the first. Thanks for the encouragement.
Luckily,I have a couple of spare antenna relays. Is there a positive way to check them, for operational speed and accuracy, or is it more a game of playing with it, to get it right? One of the relays, is my second ever "electronics project". I built an antenna relay, for my first set of boat anchors, back when I didn't know what a "Dow Key" was. If I recall right, it is not just an antenna relay, like the Dow Key in question, but I wired a circuit, to Open up the Stand By/Receive circuit, on my first HQ 150. I'm going to have to look around for that one. Otherwise, I have an N.O.S. 117VAC Dow Key, which I bought from Henry Radio, about 8 months ago, off of eBay. (Lord have they gone up in price, I remember buying them for $20 at R.V. Weatherford Electronics, in the 70's, this one cost me $100 +/- a few $, with shipping, from one side of L.A. County to the other end of the county.
Now, the big question. I am looking into the case, and do not see a way of pulling that coil out, without doing major meticulous surgery, pulling apart MAJOR pieces. This is something I have always avoided. The inside is pretty clean. I don't see a desire to want to do a "Off-frame" restoration. But, I am guessing that disturbing major components, will cause a need for re-alignment. If, I am going to go that far, it's going to be down a while, as I have ZERO experience at re-alignments. Are there any preventive measures you would recommend (I see no can, or electrolytic capacators, mostly "Orange Drop"-so I am guessing I am good there). Should I contact Gary, WZ1M, about rewinding the three transformers, in it, maybe? I don't have a lot of money. I mainly want a good working, but reliable, HQ 150. Between it and a 75A-1, those were the two I had, from years past, that I HIGHLY regretted ever selling. Now that I have one of each, I really don't want to let either, go. I'd like to keep them both in good reliable shape.
A couple more things, for now.
One-Any suggestions, on how to take it apart? Do you have any experience with this specific model? It looks like a big job, I DO NOT WANT TO MESS IT UP. I expect that you'll likely be getting several emails, from me, so that I don't clutter the boards with my novice-like questions. The book gives great instructions on how to make adjustments in realignment, but not much in the way of an "exploded view" o see how it all goes together.
Second-Should I try to re-use the same tube that the burned coil is wrapped around, or should I get a new one? If so, where do I look, and what material is best? It looks like this one is micarta, maybe, or some sort of a phenolic resin impregnated man made material, a "Laminated" tube of sorts. Any suggestions?
You might go over to http://tubes_tubes_tubes.tripod.com/id213.html
The guy has some boat anchor parts. He parts them out. He does not have any for the HQ-150 but he does for the HQ-140X, which I have been told is similar. He wants $6.00 each for the various coils, plus shipping, if you can figure out which ones you need. I suppose a careful comparison of the 150 and 140X schematics would be required first, but if they coils will work it sure sounds preferable to rewinding your current coils and also not terribly expensive.
Robert, you seem to be coming up with LOTS of good news for me today. I need to buy you a beer, or your favorite beverage, some day.
Pomona, CA-Soon to be an Okie.....
I just went over his list, and the parts lists from the 140, and the 150, in their respective manuals, as well as the schematics, and sent Gary an email wanting to purchase SEVERAL of those parts. 3 cans, the power transformer, and 3 of the 4 antenna coils in the bank where the one was, that I burnt up.
Originally Posted by WB5WSV
THANK YOU for the info. It has been of great help, and now I will have a few spare parts, that are things likely to go bad, and potentially difficult to find. With the experience I will gain, from doing this coil replacement, then realignment, I think I will be able to tackle future projects, with much less hesitation. My color blindness always scared me away from doing much electrically, or electronically. I am always afraid of getting colors crossed, or misreading color codes, then causing more damage, than I began with.
WRONG, it was!!!
Originally Posted by W3RXO
Hope he can help you out. I found that website when I was trying to find a replacement for a 2nd LO coil I broke on a NC-155 I was working on. Unfortunately he did not have that part, but I filed that place away for future reference.
I got my ham license in OK when I lived there in the 70's and then moved to Los Angeles; stayed in Calif for 10 years. Hope you enjoy it in OK. Lots of good hams and I still have friends there.
Best of luck!
I am waiting for him to respond. Hopefully, he'll still have them. But I did find another guy, who has some of those parts, and if Gary has already sold his, I'll go to the other fellow.
Okay, here's a question. How do I get knobs, that are frozen to the shaft, off of the shaft? BOTH the Main Tuning and the Band Spread knobs, each have BOTH, of their set screws completely removed. I do not want to pry, except with a soft rubber covered shaft, but even that, doesn't want to get the knobs to move. Do I spray in some lubricant? I don't want to get a chemical reaction, which might stain the face plate. Any suggestions? Anyone? I am afraid of breaking them then having a heck of a time, finding new ones, let alone the cost of the new ones, and whether or not they would be originals, like this. Wooden wedges, maybe? I shudder to think of the damage they may do. Help???