MRF 477 substitute?
AJ Sanderson
power loss. What circuit changes would have to be made to accomodate the
1969?
Thanks,
AJ
SeanH378
replaced with a mrf-455. All of the newer lincolns come that way
Sean
AJ Sanderson
Yes, I've heard this too however I have yet to see any specific conversion
plans to mount/ hookup the 455. I understand it is quite an undertaking
though and that's why I'm considering the 1969 at the loss of some power
output. I think with the 1969, I'd have to change at least the output
circuitry and I was looking for some suggestions from someone who might have
done it.
Appreciate your input!
AJ
www.TimNebo.com
>Subject: Re: MRF 477 substitute?
Tim Nebo
Scott (Unit 69)
"www.TimNebo.com" wrote:
>
> doesnt the 455 just involve reversing the leads of the final?
>
> >Subject: Re: MRF 477 substitute?
>
An MRF 477 and a 2SC1969 and such are TO-220 cases. They are about
1cm x 1cm x .5cm with the three legs pointing down. A 3 pin voltage
regulator on the side of the case (green 2SAxxxx) is a TO-220. An
MRF455 is the small size round pill. An MRF454 or 2SC2290 or 2SC2879
are the larger round pills. Hope this helps. Stay dry!
ye...@removecet.com
(www.TimNebo.com) wrote:
>doesnt the 455 just involve reversing the leads of the final?
Uh-oh, now Timmy's trying to sound technical.
Dave Hall
Ok, here's what I know on the subject. First off, an MRF 477 is based
BEC, with the emitter lead grounded to the case, which allows you to
mount it directly to the heatsink without an insulator. When changing to
a 2SC 1969, which is based BCE, you will have to swap the collector and
emitter leads, and insulate the case from the heatsink.
Once the mounting problems are solved, you should be fine. Yes, the 1969
is a lower power device (25W vs. 45W), so you will get less out. I've
never done this replacement myself so I don't have hard data to compare
to.
Dave
"Sandbagger"
Dave Hall
I once did an MRF 455 conversion in a President Jackson. It was quite an
undertaking from a mounting standpoint. But once I managed to get the
device properly mounted with a good heatsink, the performance was not
too bad, and the 455 device is a bit "beefier" than the 477, and can
stand up to more abuse. Power output fell from 45 watts on SSB (with
the 477) to about 37 with the 455.
The main reason why I did the conversion was that the person who owned
the radio was constantly blowing the final. I don't know what he was
doing to it, it was biased fine, and tuned correctly. Once I made the
change, he never blew the final again.
Dave
"Sandbagger"
AJ Sanderson
> BEC, with the emitter lead grounded to the case, which allows you to
> mount it directly to the heatsink without an insulator. When changing to
> a 2SC 1969, which is based BCE, you will have to swap the collector and
> emitter leads, and insulate the case from the heatsink.
>
> Once the mounting problems are solved, you should be fine. Yes, the 1969
> is a lower power device (25W vs. 45W), so you will get less out. I've
> never done this replacement myself so I don't have hard data to compare
> to.
>
> Dave
One time soon, I'm going to try it. I think I'd rather lose some power with
the c1969 as opposed to possibly heavily modifying the chassis to accept the
455. I can always boost the output power in other ways if needed anyway. I
was still wondering about the LC output circuits and whether or not they
would have to be changed since the power output would change. Probably not
since the difference really isn't a large one.
AJ
AJ Sanderson
> BEC, with the emitter lead grounded to the case, which allows you to
> mount it directly to the heatsink without an insulator. When changing to
> a 2SC 1969, which is based BCE, you will have to swap the collector and
> emitter leads, and insulate the case from the heatsink.
>
> Once the mounting problems are solved, you should be fine. Yes, the 1969
> is a lower power device (25W vs. 45W), so you will get less out. I've
> never done this replacement myself so I don't have hard data to compare
> to.
>
> Dave
One time soon, I'm going to try it. I think I'd rather lose some power with
Keyclown Busters
news:<20020908190007...@mb-dd.aol.com>...
No, you drug and booze soaked nwa wanna be, whose parents kicked you
out. You High School dropout whose life fantasy is 'pimping hoes"
NO!!!
A MRF 455 and an MRF 477 are completely different cases. Retards like
you don't even hope to retain that info, cuzza all the drugs ya do.
Scott (Unit 69)
to point out that you catch more flies with honey then vinegar.
(I mark quite a bit of trash as read with my rolling kill-file)
Keyclown Busters
As if I care about catching keyclowns in any way except with the law.
What is one good reason a law abiding citizen would have to "catch"
one of you pond scum in any other manner? None.
BTW, you HAVE to mark it as already read, you certainly cannot do a
thing about it. You are just one more impotent federal criminal,
losing a the battle to have to hear the truth about yourselves.
"Scott (Unit 69)" <scott_...@yaSPAMhoo.com> wrote in message news:<3D7D216D...@yaSPAMhoo.com>...
Dave Hall
You'll have to find the data sheets and compare the impedences of both
devices, to find out if any circuit changes are needed.
Dave
"Sandbagger"
Brainbuster
"AJ Sanderson" <alph...@nospam.com> wrote in message
news:albes2$ac$1...@nntp9.atl.mindspring.net...
> I've read that a C1969 final can replace the MRF 477 at the cost of some
> power loss. What circuit changes would have to be made to accomodate the
> 1969?
As mentioned by someone else, the pin-out is different.
In the Lincoln, this can be got around by moving some of
the components to different holes in the board.
Yes, this does give a lower output power. Although the
1969 is capable of putting out the standard power (it is
used in some small amps), the internal capacitance, gain,
etc will be different... resulting in the lower output.
The MRF455 does take some fitting, with a change of
mounting type. I have the information somewhere in my
books.
Someone once suggested a "2SC1945" to me. According
to my databooks, the pin-out matches and it is capable of
the power output required.
I have never tried one myself, but I know that they are
quite cheap over here.
If you try one, let me know how it goes.
Regards,
Peter.
AJ Sanderson
> In the Lincoln, this can be got around by moving some of
> the components to different holes in the board.
>
> Yes, this does give a lower output power. Although the
> 1969 is capable of putting out the standard power (it is
> used in some small amps), the internal capacitance, gain,
> etc will be different... resulting in the lower output.
Correct me if I'm wrong, but a reduction of power by 1/2 is a 3 db decrease
(I'm guestimating that the 1969 would output about half the power of the
477). The person on the receiving end wouldn't notice much difference.
Actually, in practice though I have found that this is not always the case.
A lot seems to depend on the conditions and set-ups.
> The MRF455 does take some fitting, with a change of
> mounting type. I have the information somewhere in my
> books.
I'm probably going to just stick with the C1969. I could go with a 455, but
then I'd have to worry about the proper fitting.
> Someone once suggested a "2SC1945" to me. According
> to my databooks, the pin-out matches and it is capable of
> the power output required.
> I have never tried one myself, but I know that they are
> quite cheap over here.
That transistor sounds familiar. I may have run across it in the past. I
believe it has about the same output as the '69, but I will have to check
into this.
>
> If you try one, let me know how it goes.
I'll leave a post. The need hasn't come up just yet, but with the half a
dozen "477" models I have here, one of the finals is sure to go one of these
days.
> Regards,
>
> Peter.
AJ
Brainbuster
news:an0lmm$r0f$1...@slb7.atl.mindspring.net...
> >
> > Yes, this does give a lower output power. Although the
> > 1969 is capable of putting out the standard power (it is
> > used in some small amps), the internal capacitance, gain,
> > etc will be different... resulting in the lower output.
>
> Correct me if I'm wrong, but a reduction of power by 1/2 is a 3 db
> decrease (I'm guestimating that the 1969 would output about half
> the power of the 477).
Actually, it is not even as bad as that... compared to the standard output.
> I'm probably going to just stick with the C1969. I could go with a
> 455, but then I'd have to worry about the proper fitting.
I am not too keen on the MRF455 conversion, it is much
better to fit a transistor that slots straight in.
> > Someone once suggested a "2SC1945" to me. According
> > to my databooks, the pin-out matches and it is capable of
> > the power output required.
>
> That transistor sounds familiar. I may have run across it in the past. I
> believe it has about the same output as the '69, but I will have to check
> into this.
2SC1945 ratings:
Vcb = 80v
Vce = 40v
Veb = 5v
Ic = 6Amp
Tj = 150º
Hfe = 10 -180
Regards,
Peter.
Bill Eitner
> > > 1969 is capable of putting out the standard power (it is
> > > used in some small amps), the internal capacitance, gain,
> > > etc will be different... resulting in the lower output.
> >
> > Correct me if I'm wrong, but a reduction of power by 1/2 is a 3 db
> > decrease (I'm guestimating that the 1969 would output about half
> > the power of the 477).
>
> Actually, it is not even as bad as that... compared to the standard
output.
You can get the stock 477 up to about 40 peak
with simple tuning. A single 1969 or 2312 is good
for around 25 peak in typical circuits.
> > I'm probably going to just stick with the C1969. I could go with a
> > 455, but then I'd have to worry about the proper fitting.
>
> I am not too keen on the MRF455 conversion, it is much
> better to fit a transistor that slots straight in.
I like the 455 conversion the way Uniden does it on
the new Lincolns. It's really pretty simple. It goes
on rear heatsink on the solder side of where the
original transistor went. All that amounts to is
match drilling two holes. Then a little heatsink compound
and a couple of sheetmetal screws and it's mounted.
Then it's just a matter of running short wires from the
leaves on the transistor to the appropriate points on
the board. The hardest part is removing the rear
heatsink so it can be drilled (and tapped if you don't
want to use sheetmetal screws). If you don't want to
do that you can fasten it to the speaker side cover.
Pick a spot, sand off the anti-rust coating, match-drill
the flange holes, put a little heatsink compound on the
spot, and mount the transistor using machine screws.
Then as above, run short wires to the appropriate points
on the board. With a standard 455 you'll end up with
about 35 peak watts when the RF chain is peaked.
With a higher gain device like a 1446 you'll get the
full 40 peak watts along with bullet-proof reliability.
> > > Someone once suggested a "2SC1945" to me. According
> > > to my databooks, the pin-out matches and it is capable of
> > > the power output required.
> >
> > That transistor sounds familiar. I may have run across it in the past.
I
> > believe it has about the same output as the '69, but I will have to
check
> > into this.
>
> 2SC1945 ratings:
> Vcb = 80v
> Vce = 40v
> Veb = 5v
> Ic = 6Amp
> Tj = 150º
> Hfe = 10 -180
It's a 15 watt device that's not in the same league as
the 455 or 477. It crosses to an MRF479.
> Regards,
>
> Peter.
--
-------------------------------------------------------------------
-=[Bill Eitner]=-
Link to A.M. Tutorial and rec.radio.cb FAQ:
http://www.bigradios.com/kd6tas
-------------------------------------------------------------------
Dave Hall
>
> > > > Yes, this does give a lower output power. Although the
> > > > 1969 is capable of putting out the standard power (it is
> > > > used in some small amps), the internal capacitance, gain,
> > > > etc will be different... resulting in the lower output.
> > >
> > > Correct me if I'm wrong, but a reduction of power by 1/2 is a 3 db
> > > decrease (I'm guestimating that the 1969 would output about half
> > > the power of the 477).
> >
> > Actually, it is not even as bad as that... compared to the standard
> output.
>
> You can get the stock 477 up to about 40 peak
> with simple tuning. A single 1969 or 2312 is good
> for around 25 peak in typical circuits.
That's about the same as I've seen as well.
>
> > > I'm probably going to just stick with the C1969. I could go with a
> > > 455, but then I'd have to worry about the proper fitting.
> >
> > I am not too keen on the MRF455 conversion, it is much
> > better to fit a transistor that slots straight in.
>
> I like the 455 conversion the way Uniden does it on
> the new Lincolns. It's really pretty simple. It goes
> on rear heatsink on the solder side of where the
> original transistor went. All that amounts to is
> match drilling two holes. Then a little heatsink compound
> and a couple of sheetmetal screws and it's mounted.
> Then it's just a matter of running short wires from the
> leaves on the transistor to the appropriate points on
> the board. The hardest part is removing the rear
> heatsink so it can be drilled (and tapped if you don't
> want to use sheetmetal screws). If you don't want to
> do that you can fasten it to the speaker side cover.
> Pick a spot, sand off the anti-rust coating, match-drill
> the flange holes, put a little heatsink compound on the
> spot, and mount the transistor using machine screws.
> Then as above, run short wires to the appropriate points
> on the board. With a standard 455 you'll end up with
> about 35 peak watts when the RF chain is peaked.
> With a higher gain device like a 1446 you'll get the
> full 40 peak watts along with bullet-proof reliability.
That's the way I did it a few years back in a President Jackson. 35
watts was the power output, and it ran cool as a cucumber.
Dave
"Sandbagger"
Bill Eitner
> > the new Lincolns. It's really pretty simple. It goes
> > on rear heatsink on the solder side of where the
> > original transistor went. All that amounts to is
> > match drilling two holes. Then a little heatsink compound
> > and a couple of sheetmetal screws and it's mounted.
> > Then it's just a matter of running short wires from the
> > leaves on the transistor to the appropriate points on
> > the board. The hardest part is removing the rear
> > heatsink so it can be drilled (and tapped if you don't
> > want to use sheetmetal screws). If you don't want to
> > do that you can fasten it to the speaker side cover.
> > Pick a spot, sand off the anti-rust coating, match-drill
> > the flange holes, put a little heatsink compound on the
> > spot, and mount the transistor using machine screws.
> > Then as above, run short wires to the appropriate points
> > on the board. With a standard 455 you'll end up with
> > about 35 peak watts when the RF chain is peaked.
> > With a higher gain device like a 1446 you'll get the
> > full 40 peak watts along with bullet-proof reliability.
>
> That's the way I did it a few years back in a President Jackson. 35
> watts was the power output, and it ran cool as a cucumber.
The stability is excellent too. In most cases you don't
even need a degenerative feedback loop.
> Dave
> "Sandbagger"
Brainbuster
news:anal11$cp0aq$2...@ID-7206.news.dfncis.de...
>
> You can get the stock 477 up to about 40 peak
> with simple tuning.
Yes, they do turn up easily, as do the Rangers, Emperors, etc.
What's that grumbling noise from the "akc" camp... something
about "typical keyclown mentality" ;~)
> A single 1969 or 2312 is good
> for around 25 peak in typical circuits.
I have known the 1969 used in small amps but, with the Lincoln
being designed to use the 477, I have known sets to put out
about 15 to 17 Watts with the 1969.
> > I am not too keen on the MRF455 conversion, it is much
> > better to fit a transistor that slots straight in.
>
> I like the 455 conversion the way Uniden does it on
> the new Lincolns. It's really pretty simple.
I haven't seen the new Lincolns. Have they started using
the MRF455 on the new models straight out the factory?
I do not think that this is something that should be attempted
by beginners. There are issues regarding correct mounting for
maximum heat transfer. Some of these transistors contain
beryllium oxide (to improve heat transfer)... beryllium can
cause lung disease if inhaled. Care should be taken not
to break the transistor.
A modification sheet I have here gives details of fitting an
MRF455, but also suggests that the 477 can be replaced
with an MRF497.
It's probably no easier or cheaper to obtain, but do you
have the spec on that one?
Regards,
Peter.
* RADIOSERVICE 39 *
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GG # 2184191
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______________________________________
Użytkownik "Brainbuster" <brain...@lineone.spamtrap.net> napisał
w wiadomości news:anlfts$4nb$4...@news8.svr.pol.co.uk...
> "Bill Eitner" <kd6...@netzero.net> wrote in message
> news:anal11$cp0aq$2...@ID-7206.news.dfncis.de...
> >
> > You can get the stock 477 up to about 40 peak
> > with simple tuning.
> > A single 1969 or 2312 is good
> > for around 25 peak in typical circuits.
* don't use 2SC1969 ! it's only 18WPEP
2SC2312 is better and more safe
the best substitute of MRF477 is MRF455 (another case, but working
in the same electrical conditions)
>
> I have known the 1969 used in small amps but, with the Lincoln
> being designed to use the 477, I have known sets to put out
> about 15 to 17 Watts with the 1969.
* You must remember about ALC ! it takes 2W at least ! than you
have only 13W PEP and it makes only 4 - 5 W AM with good modulation.
>
> > > I am not too keen on the MRF455 conversion, it is much
> > > better to fit a transistor that slots straight in.
> >
> > I like the 455 conversion the way Uniden does it on
> > the new Lincolns. It's really pretty simple.
* yes, it's pretty simple, but radios made now a days are much
worse, than radios made in early 90'ties.
>
> I haven't seen the new Lincolns. Have they started using
> the MRF455 on the new models straight out the factory?
* this factory is in France, worse factory than Philippines. They
are making labels of Philippines, but it's french production
>
>
> A modification sheet I have here gives details of fitting an
> MRF455, but also suggests that the 477 can be replaced
> with an MRF497.
* or MRF454 as well
Best regards,
Chris,
Poland
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