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Components and Circuits For discussions about component types, alternatives and availability, circuit configurations and modifications etc. Discussions here should be of a general nature and not about specific sets. |
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15th Jul 2018, 7:25 am | #21 |
Heptode
Join Date: Jun 2006
Location: Eindhoven, Netherlands.
Posts: 640
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Re: “New” AF126 duff
That's an interesting looking OC170.
The Philips/Valvo/Mullard version has a housing like the AF114/5/6/7/8. Jac |
15th Jul 2018, 11:48 am | #22 |
Moderator
Join Date: Jan 2003
Location: Ipswich, Suffolk, IP4, UK.
Posts: 21,192
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Re: “New” AF126 duff
Some OC170's only had three leads, but I've never been able to find data for them.
https://www.vintage-radio.net/forum/...ad.php?t=69688
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Graham. Forum Moderator Reach for your meter before you reach for your soldering iron. |
15th Jul 2018, 12:11 pm | #23 |
Heptode
Join Date: Jun 2006
Location: Eindhoven, Netherlands.
Posts: 640
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Re: “New” AF126 duff
Sorry Graham that my photo is not too clear. This OC170 does have 4 wires.
I can't make a new photo, since I used it in my Sony to replace a defective 2SA70. Jac |
15th Jul 2018, 2:01 pm | #24 | |
Dekatron
Join Date: Dec 2007
Location: Haarlem, Netherlands
Posts: 4,185
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Re: “New” AF126 duff
Quote:
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15th Jul 2018, 2:29 pm | #25 | |
No Longer a Member
Join Date: Oct 2016
Location: Maroochydore, Queensland, Australia.
Posts: 2,679
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Re: “New” AF126 duff
Quote:
169 was for IF amp in AM & FM receivers ft 70MHz. 170 mixer osc SW and MW radios & 10.5MHz IF's, also ft 70MHz. 171 shown in the manual as 100MHz grounded base amplifier. All characterized by very low collector-base capacitances and not requiring neutralization when used as IF amps. Wonderful transistors, but unfortunately identical physical construction to AF114-118 and doomed to tin whisker death. AF178's make great replacements for these too. |
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15th Jul 2018, 2:57 pm | #26 |
Moderator
Join Date: Jun 2003
Location: Oxford, UK
Posts: 27,787
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Re: “New” AF126 duff
They are basically the same transistor as the AF114-7 though the stated ft is a bit lower. I suspect Mullard were getting a lot of variation in early production and tested each one, marking them accordingly. By the time Mullard switched to Pro-Electron codes they were getting much more consistency with reliably higher ft ratings.
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15th Jul 2018, 4:08 pm | #27 |
Triode
Join Date: Jun 2018
Location: Oxford, Oxfordshire, UK.
Posts: 23
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Re: “New” AF126 duff
Glad to see my (deserved) misfortune with that AF126 has inspired some interesting peripheral debate.
Maybe also of interest, in addition to my current endavours, I recently swapped an AF114 for an AF124, in the fm tuner module of a Roberts R700. In that case, it transpired the pcb couldn’t have been designed better for the AF124. The pcb holes under the original AF114 were in a square, and in the correct AF124 sequence. Makes me wonder whether somebody involved in the design might have had an incling that an AF124 might one day come to live there. |
15th Jul 2018, 11:44 pm | #28 |
No Longer a Member
Join Date: Oct 2016
Location: Maroochydore, Queensland, Australia.
Posts: 2,679
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Re: “New” AF126 duff
Yes, those Tesla ones had a near identical physical size to the original OC170/AF114 etc, but a small flare or lip on one end of the case and filled with a lovely looking green resin rather than the silicone grease of the Philips/Mullard types. Though I have never actually cut a Tesla one open yet, as all that I have are ok so far. But for the most part at least, resin filled germanium transistors appear to be immune from whiskers.
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31st Oct 2018, 1:23 pm | #29 |
Heptode
Join Date: Jan 2016
Location: Nottinghamshire, UK.
Posts: 676
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Re: “New” AF126 duff
I Have seen some Tesla OC170s for sale (a bit expensive though) I take it these would drops right in as replacements for AF117s? The add says they are a replacement for AF116s I have used OC169s (Tesla resin filled) as AF117 replacements & they were great and come up rarely on e bay the OC169s were from Cyprus!
Kev |