|
Hallicrafters s-38C question
Hey folks, got a question: I just bought a S-38C and have replaced
most of the resistors. I will be replacing the rest of the capacitors this week. I've also replaced all 5 tubes with new ones from AES. The radio does work a lot better than it did when I first got it, but two problems remain: 1) I only pick up 3 local AM stations (I live in downtown Washington, DC.) Is this something I should be concerned about? I am new to all of this, and I am still learning... but it seems to me that this radio should be picking up more than 3 stations. I have a pretty big antenna attached to it, so I'm pretty sure that's not the problem. Is living smack-dab in the middle of downtown the reason why I can't pick up any AM stations besides the local megawatt monsters? Or might the poor reception be due to the fact that there are still 5 wax capacitors that haven't been replaced? Bands 2 and 3 pull in tons of stations; band 4 only pulls in a few but I'm not worried about that. 2) When I first got the radio, it worked but not very well. The bandspread tuner worked fine, but after I operated it for a few hours and then turned it off and started ripping out caps and resistors for replacement, the bandspread didn't work the way it used to. Now, it tunes just fine from 0 - 70, but when you turn it past 70 a very loud crackle is heard, and then there's nothing but a soft buzz. If you turn the knob back down below 70, the stations come back. Besides this problem, the bandspread tuner works like a champ. I've been having a great time restoring this thing, and learning from my mistakes. I've got a shipment of the remaining capacitors that I couldn't find at AES coming to me this week from Mouser... when I'm done replacing those, there won't be much left to replace! Thanks. chris |
"Chris Kilmer" wrote in message
om... Or might the poor reception be due to the fact that there are still 5 wax capacitors that haven't been replaced? Yes. You should also carefully clean the bandswitch, along with other controls such as volume, etc.. Corroded/gunky contacts on the bandswitch are an almost-universal problem in multi-band radios that have been sitting around for a long time. DeOxit spray cleaner is a favorite among restorers. You can also use spray tuner cleaner from Radio Shack, etc. Phil Nelson http://antiqueradio.org/index.html |
|
"Chris Kilmer" wrote in message om... Hey folks, got a question: I just bought a S-38C and have replaced most of the resistors. I will be replacing the rest of the capacitors this week. I've also replaced all 5 tubes with new ones from AES. The radio does work a lot better than it did when I first got it, but two problems remain: 1) I only pick up 3 local AM stations (I live in downtown Washington, DC.) Is this something I should be concerned about? I am new to all of this, and I am still learning... but it seems to me that this radio should be picking up more than 3 stations. I have a pretty big antenna attached to it, so I'm pretty sure that's not the problem. Is living smack-dab in the middle of downtown the reason why I can't pick up any AM stations besides the local megawatt monsters? I don't think so. You should hear dozens of AM broadcast stations. Or might the poor reception be due to the fact that there are still 5 wax capacitors that haven't been replaced? Bands 2 and 3 pull in tons of stations; band 4 only pulls in a few but I'm not worried about that. Yeah, don't jump to any conclusions until you've replaced the capacitors. And be sure the alignment is correct. The RF aligmnent can be way off on the top three bands and the radio will still recieve stations because these bands have little RF selectivity. The alignement on the AM broadcast band is more critical. 2) When I first got the radio, it worked but not very well. The bandspread tuner worked fine, but after I operated it for a few hours and then turned it off and started ripping out caps and resistors for replacement, the bandspread didn't work the way it used to. Now, it tunes just fine from 0 - 70, but when you turn it past 70 a very loud crackle is heard, and then there's nothing but a soft buzz. If you turn the knob back down below 70, the stations come back. Besides this problem, the bandspread tuner works like a champ. One, or both, of the plates on your bandspread capacitor is bent. These plates are very vunerable due to their length and position. You might be able to spot the bent plate by carefully eyeballing each plate as it rotates into it's closed position. If it goes off center between the fixed plates, it's probably touching the fixed plates. A bit of gentle bending will put it right. It's best to close up the band spread cap whenever servicing the radio. Especially when replacing the 12SA7! I've been having a great time restoring this thing, and learning from my mistakes. I've got a shipment of the remaining capacitors that I couldn't find at AES coming to me this week from Mouser... when I'm done replacing those, there won't be much left to replace! Thanks. chris If you need any alignment tips, fell free to ask. You can do a good job on this radio without a signal generator! Frank Dresser |
|
|
|
|
|
I MAKE CARDBOARD MULTI-SECTION CAPACITORS SPECIFICALLY FOR THES-38
SERIES OF SETS. SEE MY WEBSITE. CHECK MY WEBSITE: www.dialcover.com Bill Turner, excuse caps, short answers, stroke. Business SASE, each order a copy of The Pocket Resource Guide. |
....... My guess is alignment, or dirty bandswitch contacts (spray them with
Deox-It, don't waste your time with Rat Shack tuner cleaner). Good luck, Mike K. I just reworked an S-38C for a co-worker. Along with the dirty switch contacts several of the grounds to the chassis had corroded and needed to be cleaned up. The wipers on the tuning caps needed attention too. My shop antenna is a 35ft wire at the apex of the garage roof. With that hooked up the little guy does great on shortwave broadcast, 75mtr AM etc. With no antenna it gets all the local stations. EdZ San Diego |
THERE HAS TO BE SOMETHING WRONG WITH THE FELLOWS SET THAT HE SAYS IS
"JUST A AA5". I WISH ALL THE AA5 WERE AS GOOD AS MY S-38-A-B-C-D-E AND SR-75. SOME OF THEM TOOK A LITTLE WORK BUT THEY COULD HARDLY BE CONSIDERED AS ORDINARY. CHECK MY WEBSITE: www.dialcover.com Bill Turner, excuse caps, short answers, stroke. Business SASE, each order a copy of The Pocket Resource Guide. |
THERE HAS TO BE SOMETHING WRONG WITH THE FELLOWS SET THAT HE SAYS IS "JUST A AA5". I WISH ALL THE AA5 WERE AS GOOD AS MY S-38-A-B-C-D- BRBR Look around the flat thing plugged into the computer thingy with all the buttons, for one called "caps lock," and push it once. Practice with it and see how it works. Don |
Dbowey wrote:
THERE HAS TO BE SOMETHING WRONG WITH THE FELLOWS SET THAT HE SAYS IS "JUST A AA5". I WISH ALL THE AA5 WERE AS GOOD AS MY S-38-A-B-C-D- BRBR Look around the flat thing plugged into the computer thingy with all the buttons, for one called "caps lock," and push it once. Practice with it and see how it works. If you'll read his sig, you'll find an explanation of the all-caps post. I'll quote his sig here, so that you don't have to rummage back through the thread. : CHECK MY WEBSITE: www.dialcover.com : Bill Turner, excuse caps, short answers, stroke. : Business SASE, each order a copy of The Pocket Resource Guide. If you ever suffer some sort of physical impairment, you may find yourself wishing that people were a bit more accommodating towards you. -- Mike Andrews Tired old sysadmin |
Mike posted:
Dbowey wrote: THERE HAS TO BE SOMETHING WRONG WITH THE FELLOWS SET THAT HE SAYS IS "JUST A AA5". I WISH ALL THE AA5 WERE AS GOOD AS MY S-38-A-B-C-D- Look around the flat thing plugged into the computer thingy with all the buttons, for one called "caps lock," and push it once. Practice with it and see how it works. If you'll read his sig, you'll find an explanation of the all-caps post. I'll quote his sig here, so that you don't have to rummage back through the thread. : CHECK MY WEBSITE: www.dialcover.com : Bill Turner, excuse caps, short answers, stroke. : Business SASE, each order a copy of The Pocket Resource Guide. If you ever suffer some sort of physical impairment, you may find yourself wishing that people were a bit more accommodating towards you. I didn't miss seeing the end-tag. Many people who post have one or more infirmaties, and draw attention to it only when it is necessary. This post got my attention because it used keystrokes that require the use of the shift key (not shift lock key), indicating that its use was optional, regardless of the comment in the end-tag. Don |
Dbowey wrote:
I didn't miss seeing the end-tag. Many people who post have one or more infirmaties, and draw attention to it only when it is necessary. This post got my attention because it used keystrokes that require the use of the shift key (not shift lock key), indicating that its use was optional, regardless of the comment in the end-tag. Now that you have a stone clad reason for messing with the guy, consider this: How were you harmed by his all caps message? Suppose it added 10 minutes to the length of time it took for him to compose the message just to add in the "optional shifts?" Ever watch a disabled person use a mouth paddle to work a keyboard? Suppose it made him feel nice in a kind of Model 15 teletype sort of way to use all caps? Either way, how were you harmed? Give the guy a break. Maybe one day you will need us to give you one. -Chuck |
Chuck Harris wrote to Dbowey:
Now that you have a stone clad reason for messing with the guy, consider this: Without regard to all that (I don't have a dog in this fight, and you make a good case) it's just as easy to leave the keyboard in lower case for all, and easier to read, to boot. -- John Miller Email address: domain, n4vu.com; username, jsm An investment in knowledge always pays the best interest. -Benjamin Franklin |
r (Mike Knudsen) wrote in message ...
In article , writes: Hello Chris,I think you should examine the RF coil assy. and check for open circuit in BC input...think about this, If this receiver had an external antenna connected and was sitting there on the BC band,turned off,and a lightning charge came along it would most likely burn out the BC RF coil,making it extremely weak on that band. This is good advice -- check that primary. I'd like to add that many antenna primaries get blown out because someone discovers that a ground makes a pretty good antenna -- because it's using the hot side of the house power wiring as an antenna. If your line bypass caps are leaky, you'll get excess AC current thrut he antenna to ground -- I've seen sparks thrown, not big fat ones, jsut enugh to let you know it isn't good for the coil. And if you have a fancy antenna system with a baluyn coil, then for 60 cycle AC, the "hot" antenna lead is as good as ground, so be sure to hook up the ground side first. Which is just hte opposite of what PL-259 coax connectors do ,,, --Mike K. Oscar loves trash, but hates Spam! Delete him to reply to me. Thanks everyone for the advice. I have since replaced all but one of the wax caps and lamentably, the AM band is totally shot now. All I get are two very strong stations and then WMAL, which I used to get fine, is all but dead (it usually comes in at 630 AM, but now for some reason it is tuning in at 500 and very very faint...) I'm a total novice at this but I guess it doesn't take a novice to realize that this thing is horribly out of alignment. I am really going to need to teach myself how to do an alignment. I just hope I don't electrocute myself! ;-) Does replacing capacitors necessarily throw a radio's alignment completely out of whack like this? I hope I used the right kinds of capacitors to replace the old wax caps. Although I am positive I ordered the right values (voltage, mmf, etc.) and triple checked everything when I replaced the old ones, I hope I got the right type of materials. I got mica caps from Mouser and AES when available, but there was one caps that I got that is a "polyester film" capacitor. Also a question about tolerances -- how important is it to get a capacitor with the exact tolerance? When I'm looking up part numbers, sometimes a capacitor won't list any tolerance at all; other times, a tolerance is listed (Say, 10%) and that's the only one they have with the voltage/farad spec that I need, but the radio's parts list requires a 5%. Will performance/safety be affected adversely if I go with a capacitor with a 10% tolerance instead of the required 5% ? Maybe it's a silly question, but it's hard to find some of these tolerances, at least in my experience. Thanks for putting up with these questions. -chris |
Chris Kilmer wrote:
r (Mike Knudsen) wrote in message ... In article , writes: Hello Chris,I think you should examine the RF coil assy. and check for open circuit in BC input...think about this, If this receiver had an external antenna connected and was sitting there on the BC band,turned off,and a lightning charge came along it would most likely burn out the BC RF coil,making it extremely weak on that band. This is good advice -- check that primary. I'd like to add that many antenna primaries get blown out because someone discovers that a ground makes a pretty good antenna -- because it's using the hot side of the house power wiring as an antenna. If your line bypass caps are leaky, you'll get excess AC current thrut he antenna to ground -- I've seen sparks thrown, not big fat ones, jsut enugh to let you know it isn't good for the coil. And if you have a fancy antenna system with a baluyn coil, then for 60 cycle AC, the "hot" antenna lead is as good as ground, so be sure to hook up the ground side first. Which is just hte opposite of what PL-259 coax connectors do ,,, --Mike K. Oscar loves trash, but hates Spam! Delete him to reply to me. Thanks everyone for the advice. I have since replaced all but one of the wax caps and lamentably, the AM band is totally shot now. All I get are two very strong stations and then WMAL, which I used to get fine, is all but dead (it usually comes in at 630 AM, but now for some reason it is tuning in at 500 and very very faint...) I'm a total novice at this but I guess it doesn't take a novice to realize that this thing is horribly out of alignment. I am really going to need to teach myself how to do an alignment. I just hope I don't electrocute myself! ;-) Does replacing capacitors necessarily throw a radio's alignment completely out of whack like this? I hope I used the right kinds of capacitors to replace the old wax caps. Although I am positive I ordered the right values (voltage, mmf, etc.) and triple checked everything when I replaced the old ones, I hope I got the right type of materials. I got mica caps from Mouser and AES when available, but there was one caps that I got that is a "polyester film" capacitor. Also a question about tolerances -- how important is it to get a capacitor with the exact tolerance? When I'm looking up part numbers, sometimes a capacitor won't list any tolerance at all; other times, a tolerance is listed (Say, 10%) and that's the only one they have with the voltage/farad spec that I need, but the radio's parts list requires a 5%. Will performance/safety be affected adversely if I go with a capacitor with a 10% tolerance instead of the required 5% ? Maybe it's a silly question, but it's hard to find some of these tolerances, at least in my experience. Thanks for putting up with these questions. -chris Questions are never silly. Well, maybe sometimes :-) The variances between say an .05 and a .047 are nil. You could recap the whole darn radio with .01 or .02 and rarely notice a difference. You're looking for the fly on the elephant's butt while ignoring that he's in the room (Yeah, I heard that from Bill Maher). I'm going to give you credit for having chosen the correct value caps and putting them in the right place but CHECK THAT ANTENNA COIL and CHECK THOSE TUBES if you haven't done so already. Has anyone mentioned that maybe you should check the antenna coil for continuity? If not, I'd recommend checking the antenna coil. Checking th antenna coil would be a good idea. Maybe it has a problem and checking it would allow you to confirm or refute that common problem. Schematics are on nostalgiaair.com and BAMA. Get dirty with the radio, don't try to rationalize it. Check the antenna coil or better still check your own work and then CHECK THE ANTENNA COIL. -BM |
Chris,
Let us know where you are located and maybe someone from the list who lives nearby can meet with you and share some of their experience showing you how to debug a problem radio in a systematic manner. If that doesn't work out, get a copy of an old tube radio servicing bk (Marcus wrote some classics) and read up on what each stage does and what the symptoms to look for are. A new book called "All American Five" is also very good. Your enthusiasm is good, but some assistance may help. By the way, the S-38 series has a "hot" chassis so use what is called and isolation transformer when working on and using it. 73 Mike KF6KXG |
"Chris Kilmer" wrote in message om... [snip] . All I get are two very strong stations and then WMAL, which I used to get fine, is all but dead (it usually comes in at 630 AM, but now for some reason it is tuning in at 500 and very very faint...) [snip] I'm confused. Where are you reading 500? I don't think this radio indicates any tuning below 540kc. Frank Dresser |
| All times are GMT +1. The time now is 02:56 AM. |
Powered by vBulletin® Copyright ©2000 - 2025, Jelsoft Enterprises Ltd.
RadioBanter.com