So this no name 250 shows up yesterday pretty beat up. Almost zero $$ invested, so maybe worth fixing ? The heatsink and cover are junk, can it be transplanted within reason to a new heatsink ?
TIA
Todd
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Random 250 question.
- Thread starter Cabover Bob
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So this no name 250 shows up yesterday pretty beat up. Almost zero $$ invested, so maybe worth fixing ? The heatsink and cover are junk, can it be transplanted within reason to a new heatsink ?
TIA
Todd
That looks like a old TNT amp, not x force tnt but like the old 250 plus long ago.
They were ok amps back in the day, have you tried it to see if it works?
73
Jeff
They were ok amps back in the day, have you tried it to see if it works?
73
Jeff
I have not hooked it up yet, came out of a SK station in Ohio.
I suppose powering it up might help determine if it's worth the effort.
I suppose powering it up might help determine if it's worth the effort.
The outside is extremely rough, cover was held on with Gorilla tape. I was very surprised when I pulled the cover at how drastically different the inside condition is.
It used to say 250 plus on the front , worn off through the years.
My brother has the TNT Super Mod with 2 MRF 455's in it
Hook it up, see if it works.
Here is the 600 plus.
And the one KW
I had a high school friend that had the TNT 12 pack, all MRF 492 transistors in it that was a monster.
My brother has the TNT Super Mod with 2 MRF 455's in it
Hook it up, see if it works.
Here is the 600 plus.
And the one KW
I had a high school friend that had the TNT 12 pack, all MRF 492 transistors in it that was a monster.
Well today I scored a real nice piece of black anodized heat sink while buying some used tools. It's a virgin piece that is about 1/4" too narrow and a few inches too long. Gotta find someone who can make a nice clean cut for me, not too concerned about the width. I have never messed around inside of any amp, but was nicely surprised to find that I could remove some screws and free the board and transistors from the beat to death heat sink. Now to make a template to transfer to new heat sink for drilling n tapping. Cover was beat too, but I was able to get it very straight, so it will get powder coated. Power wires (10 ga. ?) seem very small for 4 x mrf455, and my soldering skills are kindergarten level, but I'm sure that I can find someone local to help with that......
Demount the board from the heatsink (correct size and already drilled for this board), clean it up and repaint it. Why try to "marry" an odd sized heatsink when you already have the original one?
The top can be fabricated easy enough, and the front panel can be sanded and repainted, re-silkscreened.
I had a friend who used to get Yaesu 101 series radios, B, E, EE, FR-FL (twins), repaint (with the correct shade) and re-silkscreen the face. Painted the top and sides too, , I don't remember if he did the back, though. Made them look brand new, after the restoration.
The top can be fabricated easy enough, and the front panel can be sanded and repainted, re-silkscreened.
I had a friend who used to get Yaesu 101 series radios, B, E, EE, FR-FL (twins), repaint (with the correct shade) and re-silkscreen the face. Painted the top and sides too, , I don't remember if he did the back, though. Made them look brand new, after the restoration.
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I haven't posted pics of the original heatsink, but if I did you would understand. It has three sections broken out and two bent.....
I think they used self tapping screws in them so make sure the holes have not pulled up on the old heatsink.. Use a larger bit or counter sink to just clean up the top of the holes.
Might be a good idea to lap the top of the heatsink with some fine grit to make sure it is a flat as possible and it would also be a good to lap the back of the transistors as well, I have seen plenty that actually have a concave from being mounted before.
A thin layer of compound, you dont need a big glob under them.
73
Jeff
Might be a good idea to lap the top of the heatsink with some fine grit to make sure it is a flat as possible and it would also be a good to lap the back of the transistors as well, I have seen plenty that actually have a concave from being mounted before.
A thin layer of compound, you dont need a big glob under them.
73
Jeff
So drill and tap the new holes and use real machine screws.
All the same as above , you want a nice flat surface under the transistors.
73
Jeff
For those that questioned my motive behind the swap -
Jeff, I remember you commenting one time elsewhere about your disenchantment with drilling n tapping 4-40, now I get it. But it did finally give me a reason to breakout my Starret 91A tap wrench.......I also went over the surface with a machinist stone to remove any burrs or raised areas around the new holes. The cover was a little rough, got it straightened out and it's at the powder coaters now.
It's mounted up now, however I am not currently set up (long story) to hook it up, but I'm going to stop by Bullet Bob's on Thursday to test this one and a Silver Streak 150 that I traded a microphone for a few days ago.
New heat sink is deeper and heavier, not sure how much difference that will make.
Todd
Jeff, I remember you commenting one time elsewhere about your disenchantment with drilling n tapping 4-40, now I get it. But it did finally give me a reason to breakout my Starret 91A tap wrench.......I also went over the surface with a machinist stone to remove any burrs or raised areas around the new holes. The cover was a little rough, got it straightened out and it's at the powder coaters now.
It's mounted up now, however I am not currently set up (long story) to hook it up, but I'm going to stop by Bullet Bob's on Thursday to test this one and a Silver Streak 150 that I traded a microphone for a few days ago.
New heat sink is deeper and heavier, not sure how much difference that will make.
Todd
Attachments
Someone mentioned silk screening the face, but I can't seem to find anything realistic for this application when doing only one. Any suggestions ?
Todd
Todd
Gamma-ray graphics.
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www.gammaraygraphics.com
I just got a great custom face plate decal from them for a friends SB-220.
73
David