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Transitors 2N5670

Posted: Mon Jul 04, 2011 3:33 pm
by DocThom
Hi, all!

The search for transitors can be a challenge. Bill Jensen offers plans for building the 1986 transistorized version of the Hieronymus Analyzer. The original plans call for three 2N5670 transistors. The only source I have found that offer this component is http://www.questcomp.com/. Go to the site and enter "2N5670" under SEARCH . The only problem is I think this company requires a $25.00 minimum order, which is enough transistors to build several instruments. At any rate, here is a source if you are searching.

Happy trails! Doc

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Re: Transitors 2N5670

Posted: Wed Jul 06, 2011 7:22 am
by JosephMax
I found the same source in my search (in China, I believe).

My local old school radio-electronics shop owner (Lasher's Electronics in Berkeley) assures me that the readily available MPF102 J-FET VHF Amplifier transistor is a spec match replacement for the 2N5670. He seemed pretty convinced it was a suitable replacement, the real difference being the MPF-102 can handle higher voltages.

I think the circuit could be built with any PNP junction transistor that can swing VHF range signals. Hieronymus used the Raytheon CK722 germanium transistor. I have ten new-old stock 2N1305 germaniums I found at a surplus seller, which match the CK722 specs. I'm going to use them to replicate Hieronymus' original CK722 circuit (not the Jensen circuit). That design ran on only 3 volts!

I want to see if there's any tangible difference between using circuits built with modern silicone J-FETs (like the 2N5670) and the old germanium junction transistors. I think all of the transistor designs of Hieronymus used germaniums. I don't know if this was by design or due to simple availability of the part - CK722s were a very popular DIY radio component in the 1950s.

Re: Transitors 2N5670

Posted: Fri Mar 31, 2017 11:00 pm
by Robotwizard
I wouldn't assume that just because the specs match that they will work the same for radionics. Spoke to Bill Jensen yesterday and he says the 2N5670 is the only one he has found that works for scalar. For some reason the MOSFET works but JFET doesn't

Re: Transitors 2N5670

Posted: Sat Apr 15, 2017 8:35 pm
by sorynzar
I think it varies by application, and how the circuit is designed

Re: Transitors 2N5670

Posted: Thu Jun 28, 2018 3:10 pm
by erik
JosephMax wrote:I found the same source in my search (in China, I believe).

I think the circuit could be built with any PNP junction transistor that can swing VHF range signals. Hieronymus used the Raytheon CK722 germanium transistor. I have ten new-old stock 2N1305 germaniums I found at a surplus seller, which match the CK722 specs. I'm going to use them to replicate Hieronymus' original CK722 circuit (not the Jensen circuit). That design ran on only 3 volts!

I want to see if there's any tangible difference between using circuits built with modern silicone J-FETs (like the 2N5670) and the old germanium junction transistors. I think all of the transistor designs of Hieronymus used germaniums. I don't know if this was by design or due to simple availability of the part - CK722s were a very popular DIY radio component in the 1950s.


I see too many years have passed and maybe you are no longer active in this forum, but could you please share the original hieronymus circuit? Btw have you verified a tangible difference between modern and old transistors?

Re: Transitors 2N5670

Posted: Thu Jul 26, 2018 4:39 am
by realityphantom
For me older components are preferable for many reasons. They are robust, durable and can take abuse. There is another aspect that I keep in mind when choosing components. Vintage components weren't always created in such sterile and controlled conditions. There was more soul as is were in their construction and they usually have more elements than just the bare minimum. On some level I feel passing energy through components with age helps get a tighter grip on reality.

Re: Transitors 2N5670

Posted: Wed Dec 19, 2018 7:58 pm
by BBS
JosephMax wrote:
I want to see if there's any tangible difference between using circuits built with modern silicone J-FETs (like the 2N5670) and the old germanium junction transistors. I think all of the transistor designs of Hieronymus used germaniums. I don't know if this was by design or due to simple availability of the part - CK722s were a very popular DIY radio component in the 1950s.


Hi guy, any news from germanium and j-fet transistor? I have some difficulty finding the old germanium transistors. You in the USA are lucky because you still have something. It would be interesting to know if it is only a matter of frequency of work or even of the material used. I do not think it's obvious as a thing.

Re: Transitors 2N5670

Posted: Sun Jan 06, 2019 11:35 am
by pelicanbill