Need IF Transformer Iron Core for Blaupunkt Verona
Barry
Blaupunkt Verona radio is damaged and I'm needing a replacement core.
Does anyone know where I can get a replacement for the core like the
one shown below?
http://n4buq.shutterfly.com/pictures/9
The top core seen in the image is good. It's the lower one whose
adjustment slot has been damaged. I have swapped their positions
where the damaged one is on top, but it takes a really large
screwdriver to get enough torque to twist it and that can't be done
with the can in place.
It appears Miller also made something very similar that might work
(perhaps Blaupunkt used Miller IFs?):
Thanks for any help.
Barry - N4BUQ
Paul P
Go to www.radiomuseum.org and post this request. Upload some pics of what
you need or the link. They are very helpful there. Since they are a
European based forum some one should have a replacement core for you.
Post your request under the radio model. It will also go to a master list
so others can see it.
But do not get offended if a moderator corrects you. They run a tight ship
and appear to have a gruff approach with the difficulties of multi lingual
board.
Did swapping the core get your AM back?
Paul P.
"Barry" <n4...@knology.net> wrote in message
news:8d144825-0c59-4ef1...@j32g2000yqc.googlegroups.com...
Barry
> Barry,
>
> Go towww.radiomuseum.organd post this request. Upload some pics of what
>
> > Thanks for any help.
>
> > Barry - N4BUQ- Hide quoted text -
>
> - Show quoted text -
Hi Paul,
I had thought about RMorg, but I'm not a member and don't think I'll
pay to join. You are correct about it being a "tight ship". I've
seen some of the moderator's comments and they do tend to be a bit
harsh but, like you said, it could just be a translation thing. I've
noticed some of your posts there as well.
I'm not sure if swapping the cores helped that much, but after
tweaking the IFs a bit more, I am now able to receive some BC and SW
stations. I still do not get much (if any) resonance on the secondary
of the 1st IF transformer and I know the sensitivity is not what it
should be.
I'm planning on replacing most of the paper and electrolytic
capacitors and I think that will probably fix most of the problems.
If I don't find a replacement core, I might craft a thin disk with a
small slot in the center and epoxy it to the top of the old core. At
least that way I would be able to adjust it with the can back in
place.
Thanks again,
Barry - N4BUQ
Doug Bannard
You might want to try to repair the damaged slug.
What I use is a high viscosity cyanoacrylate adhesive (gap filling type) and
its accelerator. If you have a good hobby shop nearby, they should carry
these materials. I buy them here in Ottawa from a company called Lee Valley
Tools.
Here's what I've done in the past:
1) Remove the slug from the transformer.
2) Take the alignment tool and wax the end of it well or coat it with any
good mold release coating.
3) Centre the alignment tool in what is left of the slot in the slug and
drip a small amount of the high viscosity cyanoacrylate around it to fill up
the excess slop in the slot. Use only enough adhesive to come up to the top
surface of the slug so that you don't end up with a lump of adhesive hitting
the top of the can when you re-assemble the transformer.
4) Holding the alignment tool very still, shoot the top of the slug with the
accelerator and the adhesive will start to cure immediately. After 5 to 10
minutes you should be able to remove the tool, but give the accelerator
another few hours to completely cure the adhesive before you try to align.
You should be left with a new slot that is stronger than the original
powdered iron.
Best regards : Doug Bannard, VE3SPF.
"Barry" <n4...@knology.net> wrote in message
news:8d144825-0c59-4ef1...@j32g2000yqc.googlegroups.com...
Paul P
capacitors and I think that will probably fix most of the problems.
Barry,
Yes. Please replace all the papers and electrolytic before you trouble
shoot any more!
That will probably bring it back to life. Also if there are the American
style Bakelite covered carbon composition resistor replace them. The
plastic looking coated restores are typically good and in tolerance.
If there is Selenium rectifier consider rebuilding it with 1N4007 diodes.
Then add a series dropping resistor to compensate for the reduced forward
voltage drop of the silicon diode. I do not remember if you mentioned B+ or
not. http://www.ppinyot.com/saba/IMG_3873.JPG
Don't resist replacing caps (or lousy resistors)....Resistance is futile.
Paul.
Jeffrey Angus
> Yes. Please replace all the papers and electrolytic before
> you trouble shoot any more!
Barry, you haven't already?
Despite the vocal minority that insist otherwise, replacing
all the _known_ suspects first is the key to success to any
old radio.
As Yonny is fond of saying, "There are only two kinds of
capacitors. Ones that have failed and ones that will fail."
Of the couple of hundred radios I worked on at my shop
before I moved, almost every one of them sprang to life
after replacing the capacitors. Those that didn't were
easy to troubleshoot as I didn't have to chase around
after several questionable components.
Jeff
Barry
>
> > Thanks for any help.
>
> > Barry - N4BUQ- Hide quoted text -
>
> - Show quoted text -
I had considered filling it as you suggest, but I know that ordinary 2-
part epoxies (et. al.) would not provide the strength or bonding
needed. I have not heard of high viscosity cyanoacrylate adhesive
before, but if it will do what you say, I'm certainly willing to give
it a try. I'll look for some.
Thanks!
Barry - N4BUQ
Barry
> I'm planning on replacing most of the paper and electrolytic
> capacitors and I think that will probably fix most of the problems.
>
> Barry,
>
> Yes. Please replace all the papers and electrolytic before you trouble
> shoot any more!
>
> That will probably bring it back to life. Also if there are the American
> style Bakelite covered carbon composition resistor replace them. The
> plastic looking coated restores are typically good and in tolerance.
>
> If there is Selenium rectifier consider rebuilding it with 1N4007 diodes.
> Then add a series dropping resistor to compensate for the reduced forward
> voltage drop of the silicon diode. I do not remember if you mentioned B+ or
>
> Don't resist replacing caps (or lousy resistors)....Resistance is futile.
>
> Paul.
To Paul and Jeff,
No, I haven't yet recapped it. I'm trying to decide if I want to
shotgun them or try to find the bad part and possibly learn something
in the process. I have recapped radios before (R-390A's) and have had
good success and there are only a small handfull of paper caps in this
radio. The rest are dogbones and I doubt any of those are bad.
As for resistors, these are the coated variety (they used fairly high-
quality components in this set) and of the ones I've checked, they do
not exhibit age creep like the non-coated carbon composition resistors
will do.
Yes, I replaced the selenium rectifier and added a dropping resistor
(I'm the guy who started that long thread regarding odd waveforms for
a non-loaded rectifier bridge about a week ago).
Thanks for all the advice. Hopefully I'll get this thing running like
it should before too much longer.
Barry - N4BUQ
Barry
>
> You might want to try to repair the damaged slug.
>
> What I use is a high viscosity cyanoacrylate adhesive (gap filling type) and
> its accelerator. If you have a good hobby shop nearby, they should carry
> these materials. I buy them here in Ottawa from a company called Lee Valley
> Tools.
>
> Here's what I've done in the past:
>
> 1) Remove the slug from the transformer.
> 2) Take the alignment tool and wax the end of it well or coat it with any
> good mold release coating.
> 3) Centre the alignment tool in what is left of the slot in the slug and
> drip a small amount of the high viscosity cyanoacrylate around it to fill up
> the excess slop in the slot. Use only enough adhesive to come up to the top
> surface of the slug so that you don't end up with a lump of adhesive hitting
> the top of the can when you re-assemble the transformer.
> 4) Holding the alignment tool very still, shoot the top of the slug with the
> accelerator and the adhesive will start to cure immediately. After 5 to 10
> minutes you should be able to remove the tool, but give the accelerator
> another few hours to completely cure the adhesive before you try to align.
> You should be left with a new slot that is stronger than the original
> powdered iron.
>
> Best regards : Doug Bannard, VE3SPF.
>
> - Show quoted text -
Hi Doug,
I got some high-viscosity CA and tried this but it didn't work. I
didn't get the accelerator, but I let the glue dry overnight with the
screwdriver in place. Unfortunately, it did a pretty good job of
sticking the screwdriver to the slug (I polished and waxed the
screwdriver tip very well before doing this). When I pulled the
screwdriver out, the CA also let go from the powdered iron.
I have a feeling that you may not have started with quite as much
damage to the slug as I have. This one looks like a small crater with
virtually nothing left of the original slot.
If anyone knows where I can find a replacement slug, I'd really
appreciate finding one. I can just barely adjust the slug with the
can cover removed and cannot adjust the slug at all with the can cover
in place due to the hole restricting the size of screwdriver point. I
suppose I could enlarge the hole in the cover, but I really would
rather not do that.
Barry
manufacturer markings on it but it does have "AF724/8Z-S9" stamped on
the side. A Google search of that didn't come up with anything
useful.
I keep wondering if perhaps these were made by J.W. Miller. From what
I've seen of the data sheets on them, the cores look a lot alike;
however, I'm not sure if the threads in the Miller transformers have
imperial or metric threads. I measured the threads on mine and it's
apparently a 0.8mm thread pitch. None of my pitch gages fits it
(somewhere around 32 but not exactly). If they are metric, then
perhaps a core from a 455kc can might fit.
Thanks for all the help,
Barry - N4BUQ
Bill M
>
> I have a feeling that you may not have started with quite as much
> damage to the slug as I have. This one looks like a small crater with
> virtually nothing left of the original slot.
>
> If anyone knows where I can find a replacement slug, I'd really
> appreciate finding one. I can just barely adjust the slug with the
> can cover removed and cannot adjust the slug at all with the can cover
> in place due to the hole restricting the size of screwdriver point. I
> suppose I could enlarge the hole in the cover, but I really would
> rather not do that.
>
> Thanks again,
> Barry - N4BUQ
Have you looked to see if there's a slot on the other end of the slug?
Sometimes there is.
-Bill
John Byrns
Bill M <radio...@geeeemail.com> wrote:
> Barry wrote:
>
> >
> > I have a feeling that you may not have started with quite as much
> > damage to the slug as I have. This one looks like a small crater with
> > virtually nothing left of the original slot.
> >
> > If anyone knows where I can find a replacement slug, I'd really
> > appreciate finding one. I can just barely adjust the slug with the
> > can cover removed and cannot adjust the slug at all with the can cover
> > in place due to the hole restricting the size of screwdriver point. I
> > suppose I could enlarge the hole in the cover, but I really would
> > rather not do that.
>
> Have you looked to see if there's a slot on the other end of the slug?
> Sometimes there is.
Bill, if you look at the picture Barry posted you will see that it is
not that kind of plain slug, it's one of those cylindrical slugs with a
stud in the center that goes both into and around the coil, hence no
possibility for a slot in the "other end", as there is no "other end".
--
Regards,
John Byrns
Surf my web pages at, http://fmamradios.com/
Barry
> not that kind of plain slug, it's one of those cylindrical slugs with a
> stud in the center that goes both into and around the coil, hence no
> possibility for a slot in the "other end", as there is no "other end".
>
> --
> Regards,
>
> John Byrns
>
>
> - Show quoted text -
Yes, that's correct. I forget the term that describes them ("cap"
core or something like that) so, unfortunately, there's no "other end"
available.
I may try using the CA glue to affix a thin metal disk with a small
slot cut in it. I don't think it will adversely affect the
permeability of the core and there's enough surface area to give it a
decent bond. I certainly can't hurt it at this point and, if it
works, it will be much stronger than a powdered iron slot.
Regards,
Barry - N4BUQ
Bill M
>
> Bill, if you look at the picture Barry posted you will see that it is
> not that kind of plain slug, it's one of those cylindrical slugs with a
> stud in the center that goes both into and around the coil, hence no
> possibility for a slot in the "other end", as there is no "other end".
Oh. Sri.
-Bill
Barry
> One of the iron cores in one of the 460kc IF transformers in my
> Blaupunkt Verona radio is damaged and I'm needing a replacement core.
> Does anyone know where I can get a replacement for the core like the
> one shown below?
>
> http://n4buq.shutterfly.com/pictures/9
>
> The top core seen in the image is good. It's the lower one whose
> adjustment slot has been damaged. I have swapped their positions
> where the damaged one is on top, but it takes a really large
> screwdriver to get enough torque to twist it and that can't be done
> with the can in place.
>
> It appears Miller also made something very similar that might work
> (perhaps Blaupunkt used Miller IFs?):
>
>
> Thanks for any help.
>
> Barry - N4BUQ
I finally got around to making a fix for this problem. See the
following picture:
http://n4buq.shutterfly.com/pictures/22
I fashioned two small disk "halves" out of thin aluminum sheet such
that when pieced together they form a small slot and then I epoxied
them to the face of the core. While I would have rather made this out
of something non-metallic, this is strong and hopefully doesn't have
too much negative effect on the performance of the transformer. The
1st IF transformer now peaks nicely on both primary and secondary
windings so it has my radio back in business.
Regards,
Barry - N4BUQ
Barry
>
> - Show quoted text -
I forgot to mention that the JW Miller cup cores wouldn't work in
these transformers. Apparently the JW Miller's are english threads
and the Blaupunkt are metric threads. The Miller core would screw
into the two plastic threaded "uprights" (the thread pitch was not
exact but close enough to work), but the thread diameter was about
0.025" larger and the can would not fit back down on the transformer
with the plastic "uprights" spread that extra width.
Barry - N4BUQ