DX 390 FET Replacement
 

The front end seems to have gone out on this set. FM seems fine, AM
works on the stronger stations, and there's nothing but a low level
noise on SW.

I'm suspecting the usual Q1 problem


What would be a good replacement? Is there a quick cure to prevent
future zappings?




mike


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..let the cat out to reply..

Many people have used an MPF102 as a
replacement. I tried it on mine and found that
it worked, but had about half the sensitivity of
the original.

The original is a 2SK152 Data can be found he
http://nte01.nteinc.com/nte/NTExRefSemiProd.nsf/$$Search?OpenForm

The replacement is a NTE312.

I scored a VHF FET from an old 46/49MHz cordless
phone, and used that. There was one drawback to my
substitution, The pinchoff voltage is different, and the RF
gain control has no effect. Therefore, the gain is set
wide open, since you cant bias the FET off. I cant
remember the FET number.

The good point is that sensitivity is hotter than with the
original.

Add a pair of 1n4148/914 diodes back to back across the
antenna jack to eliminate this problem in the future.

YMMV - Good luck

N3KCT wrote:

Many people have used an MPF102 as a
replacement. I tried it on mine and found that
it worked, but had about half the sensitivity of
the original.

The original is a 2SK152 Data can be found he
http://nte01.nteinc.com/nte/NTExRefSemiProd.nsf/$$Search?OpenForm

The replacement is a NTE312.

I scored a VHF FET from an old 46/49MHz cordless
phone, and used that. There was one drawback to my
substitution, The pinchoff voltage is different, and the RF
gain control has no effect. Therefore, the gain is set
wide open, since you cant bias the FET off. I cant
remember the FET number.

The good point is that sensitivity is hotter than with the
original.

Add a pair of 1n4148/914 diodes back to back across the
antenna jack to eliminate this problem in the future.

YMMV - Good luck

Do you think the NTE-312 would perform the same as the 2SK152?


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Do you think the NTE-312 would perform the same as the 2SK152?

The NTE-312 is the cross for 2SK152. They should be
electrically identical, and should perform as such.

"N3KCT" wrote in message
...
Do you think the NTE-312 would perform the same as the 2SK152?

The NTE-312 is the cross for 2SK152. They should be
electrically identical, and should perform as such.

Well, not exactly. It's the closest match NTE has to the 2SK152, and
"should" function in most circuits. That isn't to say it is an exact
replacement. The NTE device may have a higher noise figure, for example,
which could be obvious on the higher bands. This company in Ireland claims
to be selling the 2SK152 for 62 US cents apiece:
http://www.donberg.ie/descript/2/2sk152.htm

The J310 FET is pretty good, and available from Kits & Parts, and either
Mouser or DigiKey; I can't remember who I got mine from. The price is right
and it might be worth buying several and swapping them in for best
performance.

"PM"

Paul_Morphy wrote:

"N3KCT" wrote in message
...
Do you think the NTE-312 would perform the same as the 2SK152?

The NTE-312 is the cross for 2SK152. They should be
electrically identical, and should perform as such.

Well, not exactly. It's the closest match NTE has to the 2SK152, and
"should" function in most circuits. That isn't to say it is an exact
replacement. The NTE device may have a higher noise figure, for example,
which could be obvious on the higher bands. This company in Ireland claims
to be selling the 2SK152 for 62 US cents apiece:
http://www.donberg.ie/descript/2/2sk152.htm

The J310 FET is pretty good, and available from Kits & Parts, and either
Mouser or DigiKey; I can't remember who I got mine from. The price is right
and it might be worth buying several and swapping them in for best
performance.

"PM"

Why is the 2SK152 so rare?


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starman ) writes:
Paul_Morphy wrote:

"N3KCT" wrote in message
...
Do you think the NTE-312 would perform the same as the 2SK152?

The NTE-312 is the cross for 2SK152. They should be
electrically identical, and should perform as such.

Well, not exactly. It's the closest match NTE has to the 2SK152, and
"should" function in most circuits. That isn't to say it is an exact
replacement. The NTE device may have a higher noise figure, for example,
which could be obvious on the higher bands. This company in Ireland claims
to be selling the 2SK152 for 62 US cents apiece:
http://www.donberg.ie/descript/2/2sk152.htm

The J310 FET is pretty good, and available from Kits & Parts, and either
Mouser or DigiKey; I can't remember who I got mine from. The price is right
and it might be worth buying several and swapping them in for best
performance.

"PM"

Why is the 2SK152 so rare?

It may be location.

That uses the Japanese numbering scheme (the "SK"), and for whatever
reasons they tend to arrive and be used in North America as replacement
parts in Japanese made equipment that uses them in the first place. Hobby
circles and repair circles don't always overlap (the less so as the years
go by), so many of the places hobbyists can get devices (more specically
buy things without having to buy the item in large quantities or order
a large order of parts) don't carry them. They aren't normally used
in construction articles over here, so such places don't bother with them,
which of course reinforces the lack of interest.

They may be a very common device in Japan (and maybe other parts of the world
that Japanese parts dominate), but they aren't over here.

Michael

"Michael Black" wrote in message
...

They may be a very common device in Japan (and maybe other parts of the
world
that Japanese parts dominate), but they aren't over here.

There have been so many types of transistors made over the years, it would
be impossible to stock them all. It's going to get harder in the future, as
manufacturing moves to multi-function integrated circuits and surface-mount
components. Stock up!

"PM"

"Paul_Morphy" ) writes:
"Michael Black" wrote in message
...

They may be a very common device in Japan (and maybe other parts of the
world
that Japanese parts dominate), but they aren't over here.

There have been so many types of transistors made over the years, it would
be impossible to stock them all. It's going to get harder in the future, as
manufacturing moves to multi-function integrated circuits and surface-mount
components. Stock up!

"PM"


Yes, I was caught up in explaining why that particular transistor might
be "rare".

The same thing really applies to most transistors. There are a handful
of transistors that are common enough for hobby distributors to carry,
and if anyone picked one off that list, it would be perceived as "rare".
It's both a cause and effect, since the construction articles tend to
use the devices that are commonly available, which makes sure the hobby
distributors carry those devices.

Someone in this thread suggested an MPF102 as a replacement, though
at least added that it might not be the best choice. THat probably
rates as the most recognizable JFET in North America, so whenever FET
is mentioned, it would tend to get suggested.

Michael

"Michael Black" wrote in message
...

Someone in this thread suggested an MPF102 as a replacement, though
at least added that it might not be the best choice. THat probably
rates as the most recognizable JFET in North America, so whenever FET
is mentioned, it would tend to get suggested.

Yeah, it's as common as Budweiser. He needs to send his money to the land of
Guinness and get the real thing. Ain't the internet great? You can sit here
in the U.S. and buy Japanese transistors from a dealer in Ireland. The
semiconductor cartel knows no boundaries.

"PM"