Progress is incremental. Those capacitors had major advantages over what came before. The "dry" electrolytics that followed them had further advantages. That's how things go.
-- Jim Mueller wrongname@nospam.com To get my real email address, replace wrongname with dadoheadman. Then replace nospam with fastmail. Lastly, replace com with us.
I think that there is a misunderstanding here. The statement to replace all the capacitors actually means all the electrolytic and paper capacitors. Usually ceramic and mica capacitors are still good and nobody replaces those unless they are proven to be bad.
The paper capacitors in the IF and RF stages need to be replaced even if the radio "works". Leaky capacitors change the voltages on the tubes causing them to work at less than their best performance. Also, these capacitors are used as supply bypasses and AVC filter capacitors. They do not affect the alignment of the set; the ceramic and mica capacitors may. Their value is not particularly critical; pick the closest modern value.
Consider the value issue. If the radio has a .05 uF, 20% capacitor in it, its actual value can be anywhere from 0.04 uF to 0.06 uF. A modern
0.047 uF 10% capacitor can be between .0423 uF and 0.0517 uF. So the 0.047 uF capacitor can be closer to 0.05 uF than the old one marked with that value.As for life expectancy, there was a time in the late '50s and early '60s when both paper and plastic film capacitors were used. The paper capacitors I have from that period are universally bad while the plastic film ones are almost always good. Plastic film has passed the test of time.
As for what type of plastic film to use, polyester (AKA Mylar) is the cheapest and has the poorest performance. But it is still better than the paper capacitors of old so it is suitable for use just about anywhere a paper capacitor was formerly used. Polycarbonate (no longer made) and polypropylene are better but more expensive. Polystyrene capacitors are also very good and inexpensive but are usually seen only in small values and are frequently not seen at all. They also have the problem that they melt at lower temperatures than other plastic capacitors and solvents dissolve them. Still, within their limitations, they are excellent.
-- Jim Mueller wrongname@nospam.com To get my real email address, replace wrongname with dadoheadman. Then replace nospam with fastmail. Lastly, replace com with us.
Wow, this thread has really taken off. It's almost like the old days of Usenet!
-- Jim Mueller snipped-for-privacy@nospam.com
To get my real email address, replace wrongname with dadoheadman. Then replace nospam with fastmail. Lastly, replace com with us.
I know the dry 'lytics were better, I have to ask what came before these wet ones with the vent hole? I really dont know...
One thing I liked about those wet ones was the threaded nut on the bottom. Very easy to install and remove! Those twist tabs on the dry caps in the metal cans tended to break off quite easily, if the cap was being removed to be reused elsewhere, and if one was soldered, it was even harder. (generally one was soldered).
I wonder why they dont make them both radial and axial? I'd think that it's just a matter of rerouting the wires from the same innards.
I hear you.....
OK. That makes sense...
I see where this can get confusing. I'll consider the polyester (AKA Mylar), but for the small cost difference, I'd probably prefer the best. It looks like polypropylene would be that choice.
Do you have any brand names to recommend for these types? (I will be buying online, there are no electronics stores around here).
Dont you mean they melt at a *HIGHER* temperature? I cant imagine how something could melt at a low temp?
Upon reading a URL that somone posted on here, I see where the audiophliles say that some caps have better sound quality, than others. On a SW radio, I'm not really looking for "precision sound", but more so for best performance from the signal coming from the antenna to the speaker. And while some (or most) of these newer types of caps are made to be used with modern gear, containing semiconductors, which are the best choice for old tube stuff. I would think that the caps should mimic the old paper caps, because that is what these circuits were designed to use. I know the values of caps are the capcitance (in MF or MMF) and the voltage. But I know there are other factors that I know nothing about. Someone mentioned tempco (is that what I read?) in another message in this thread. What the heck is that?
Either way, I do believe the caps should be similar to the original ones to work properly. Just made from better materials.
I miss those days. The majority of newsgroups are either dead or filled with morons or off topic political based fighting and name calling these days. There were many worthwhile newsgroups that I used to enjoy, and I wont even go there anymore.
I cant understand where everyone went. I know almost everyon has an account with that miserable facebook these days (except me), but I cant say I have ever seen any useful discussions on FB. For the brief time I did connect to FB, what I saw was just a lot of links to websites dealing with world affairs, and lots of rude comments about them. Or pictures of people when they were drunk, with more rude comments.... Not to mention the 20 or more ads on each page. The day when FB becomes the entire internet, is the day I pull the plug. (And actually I cant even use FB if I did want to. My only affordable internet access is still dialup, because that's all there is in this rural area where I live, and bloated websites like FB and most of the news media sites wont even load anymore).
I get mine from here:
-- Jeff-1.0 wa6fwi http://www.foxsmercantile.com
Hard to believe r.a.r+p dates back to September 1994. I was one of the founding members under my email address at the time, snipped-for-privacy@savvy.com
-- Bill
Interesting...but I never had what I presume to be a European machine.
Started with a Model 15 KSR, then a Model 32 ASR and finally a Model 28 KSR -- with a home brew digital/electronic replacement for the paper tape. Today it's all pixels.
When I was a kid, I liked taking old radios to bits. A mains reservoir electrolytic I "autopsied" had a centre electrode that was sort of like a curvy column (for maximum surface area) up the middle, the can was the other electrode, it was completely filled with electrolyte. Another old radio had a compartment under the one that housed the chassis, it contained a huge slab flat wound paper capacitor - it must've weighed at least 7lb.
That's not far different to what I said - certain types of cap you learn from experience should be regarded as suspect. More reliable types can deteriorate if they're close to the heat from power tubes. Anything that can affect RF/IF tuning shouldn't be disturbed unless you know its faulty.
Lorenz Lo-15c
I started with a Teletype Model 15 in 1972, then a Model 19 in 1974. Then got my grubby little hooks into a Model 32. I acquired the Lorenz in 2007. It used to be in the German Consulate in Los Angeles.
For the terminal units, I started with a used homebrew with the classic 88 mH toroids. Then graduated to the HAL ST-6000, then the ST-8000 and currently the ST-8000A.
I'm waiting for the last of the PK-232 boxes to finally die. Because
200 Hz shift is NOT equal to 170 Hz shift. Regardless of what their manual says.-- Jeff-1.0 wa6fwi http://www.foxsmercantile.com
quite impressive!
Wow! Big bucks. HAL made nice equipment -- that I couldn't afford. I had a W6FFC (Irv Hoff?) ST-6 TU kit, a 3" home brew solid state scope from
73 magazine for a tuning indicator and a W6FFC AFSK unit (for 2 meter RTTY) all built into a Drake 4-line cabinet to match my Drake 4B line, Heathkit scope bezel, CRT, mu metal shield and Heath knobs. Was a avionics guy in the Air National Guard at the time and was able to use the Airframe sheet metal shop to create the chassis and front panel.A PK-232 you say? I used a KAM+ that allowed you to very easily change speeds (and maybe shifts) on the fly on RTTY. As a matter of fact, that's how I worked the guy from [Russian] Georgia who was operating in NORTH Korea on rtty. Everybody was calling him using the US 60 wpm speed, but I was able to realize he was using the European speed (forgot what that was), but changed it on the fly, worked him and got the North Korea QSL to prove it.
73
YOu started withe the kit, I could not afford that in the 1980'S. Wired up a version of the st-6 from a schematic in Ham Radio and the matching tone generator from the RTTY Journal on a piece of pref board by hand. I did have a Heathkit counter to adjust the tones. Stuff looked like crap, but worked very well.
At that time there was about 20 local hams on the 220 FM band. I still dabble with receiving rtty on the Mod 19 from time to time.
Heh, I hung out on 145.85 MHz on AM AFSK.
That's a pretty big chunk of "e-waste" let me know when you need to "properly" dispose of it. ;-)
-- Jeff-1.0 wa6fwi http://www.foxsmercantile.com
Although they did not list the shipping cost, the cost of the caps is quite reasonable, and they do have a fairly good selection. What I am not seeing is any brand name. Who makes them? Are they US made?
If the shipping is reasonable, I'd likely order from them based on your referral, but it would be nice to know a little more about them.
That sort of thing I never encountered. That must have been REALLY old! Most of the stuff I worked on, was mid 40s thru 60s. I had a few of those old wooden radios that stood about 40" tall and had a round top. Those were some of the harder ones I tried to work on, and the tubes were unusual. I know those were the ones that had those wet caps with the top vent hole. I also recall that the speaker magnet was an electro-magnet and was also used as a choke for the power supply. Those were some of the oldest things I worked on.
The surest sign of success is abuse and pollution. Usenet is obviously successful.
I wrote this rant on Usenet "personalities" maybe 20 years ago when observed the same problems you've mentioned:
Probably Reddit:
I have a Facebook account and I'm not afraid to use it. Mostly, I hang round two local groups that deal with the usual neighborhood problems. It works fairly well, and much better than the old bulletin board outside the post office or market. It might work better if I take the time to learn how to navigate the Facebook maze.
Check into alternatives to cable and telco internet. There are plenty of WISP's (wireless internet service providers). Maybe share a wireless backhaul connection with the neighbors. I setup a few such systems using various backhauls (including satellite). They were slow and clumsy, but sufficient as the alternative would have been dialup or no internet.
Also, you can really cut down on the traffic by using the mobile URL's instead of the usual URL. Try it: etc... You may need to install a browser addon that fakes the user agent string, so that the web pile thinks you're using a smartphone. For example: There are others. There are also browser tweaks for dialup: Or, you can switch to a text based browser. However, I'm not sure it will work with Facebook.
-- Jeff Liebermann jeffl@cruzio.com 150 Felker St #D http://www.LearnByDestroying.com Santa Cruz CA 95060 http://802.11junk.com Skype: JeffLiebermann AE6KS 831-336-2558
I'll have to look at those. I personally hate web based forums, but that is mostly bcause on dialup, it takes too long to load the pages. I used to go ro some of those Yahoo Groups, years ago, but even them have been taken over by spam trolls and abuse.
Some people seem to like FB. I actually had an account for a very short time. After spending many hours trying to understand how to use it, (and it's not easy), I made a page for a small non-profit event that I run. It took less than one week for idiots to ruin it. Nothing posted to it had anything to do with the topic. It became a place for people to beg for money, call other people names, discuss politics, and post photos of themselves drunk. Since I could only work on it from the library or a local restaurant (using the WIFI), I finally turned the page over to another member of our group and said here is the group and the password, FIX THIS. After a week or so, they said that I had not made it limited enough, and it was beyond fixing. I told them to remove everyone from the "friends list" except the actual members of our organization. But even doing that did not seem to stop the abuse of the site (page). Out of extreme frustration, I deleted the whole thing, and said I would never touch FB again.
I am a lot more limited than you could imagine. My nearest neighbor is over a mile away. The nearest small town is 5 miles, the nearest large city is 55 miles. I can not get a reliable cell phone signal here. To make a call, I have to either drive up the hill, or (in warm weather), I may go up on the roof. Because of that, I MUST keep a landline (which also takes care of my dialup needs). There is no cable. The only way might be a satellite dish. And that would cost me at least $100 per month. I dont want the tv part of it. I dont watch much tv and I only watch ME-TV (oldies). My antenna on the 35 foot tower I made from pipe, works pretty well for tv, but only gets stations from one direction, since there's a hill on my other side.
I am going to check on some of these text based browsers and stuff like that though. At one time, I used a browser called "Off By One", which only displayed text and pics. But it will not work on any websites using HTTPS (secured), and many of them are using that now, even wikipedia.
Thanks
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