FET replacement on 1970s vintage am/shortwave receiver--Use sameexact or replace with better?
 

Michael Black wrote:
"Michael A. Covington" ) writes:

My understanding is that there is appreciable unit-to-unit variation with
FETs.

Why are you considering only 2SK types and not, for example, the common
MPF102?



I don't know why he's looking at "oddball" fet types, but he did say
he wanted to try to improve reception by using a better device. The
MPF102 is about as generic as you can get when it comes to a JFET; indeed
as with some other components, I see the part number not as specifying
a particular component, but defining the type of device wanted. If he
wants "better performance" he'll need a better than average part, but
as pointed out in one of the newsgroups he's posted to, the rest of
the circuit will likely require adjustment to see any improvement
with a better device.

Michael

In the latter 70s I had a Kenwood R599 that was absolutely terrible in
regard to overload. There was a short article in one of the ham mags of
the era that suggested replacing the front end FET with a newer device.
I don't recall the device numbers and haven't been able to locate the
article again.
The difference was remarkable. Before, I was completely blanked by a
fellow ham about 2 blocks away, afterwards I couldn't detect that he was
on the air unless I was tuning close to him on the same band.
It was a very worthwhile replacement and I wish I could find the article
again to see if it could apply to some of the other late 60s/early 70s
receivers that were so lousy in this regard.

-Bill M