[Premium-Rx] Reaction Instruments 685 AM-FM demodulator

[Peter Gottlieb]

I am awaiting some ordered filter components before bringing the receiver back onto my bench. I did verify that the current design brings the 2N2222A bases to -12 volts so will be replacing them with the J106 FETs I have already received when I open it up again. The PCB pattern has four holes and matches the pattern used for the 2N4447's used, and it appears those parts were replaced at some point and 2N2222As were substituted. I would be interested in hearing if this was done in any other receivers so if anyone has occasion to open up this assembly please take a look and let me know. 


Peter

> On Nov 19, 2015, at 10:02 AM, Charles Steinmetz <csteinmetz at yandex.com> wrote:
> 
> Closing the loop:
> 
> Peter was originally looking for 2N4447 JFETs to repair the subject receiver.  I noted that Crystalonics makes the 4447 and also the similar 2N5432, and suggested contacting them.  I also noted that the very common (and inexpensive) J106 should also work in place of the 4447s.
> 
> Peter wrote:
> 
>>> The 2N5432 is interesting, while non stocked it is "available" from Digikey for only $46.76 each.  Yikes.  There are some sellers of them on ebay, one guy has them for $4.50 each plus $1 each shipping.
> 
> I replied:
> 
>> All of the 2N5432s listed on ebay are almost certainly counterfeit -- don't bother with them.  Crystalonics sells small quantities directly, so it's worth a call to inquire about both 4447s and 5432s.
> 
> I was buying some other Crystalonics parts today, and was reminded that they have a price list online -- so I looked up the 2N4447 and 2N5432.  4447s are $10.25 each, and 5432s are $7.70 each.  Not jellybean cheap, but not bad for new parts direct from the OEM (if I were going this way, I'd go straight to the 2N4447s).  Crystalonics has a $25 minimum order for noncommercial customers, and takes payment by credit card.
> 
> I'm not suggesting that you should get 2N4447s, assuming the J106s work well (which I expect they will).  Just observing that things are not always as hard as one thinks they will be.  It pays to look or call.
> 
> Best regards,
> 
> Charles
> 
> 
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