Path: ...!weretis.net!feeder6.news.weretis.net!usenet.blueworldhosting.com!diablo1.usenet.blueworldhosting.com!feeder.usenetexpress.com!tr2.iad1.usenetexpress.com!69.80.99.27.MISMATCH!local-2.nntp.ord.giganews.com!nntp.supernews.com!news.supernews.com.POSTED!not-for-mail NNTP-Posting-Date: Fri, 05 Apr 2024 15:38:46 +0000 Subject: Re: Favourite Test Equipment Newsgroups: sci.electronics.design References: <9k7j0jlnbhs8qfg5m17pium0835meean83@4ax.com> <1qrjb8o.u2ipkmlx8gzsN%liz@poppyrecords.invalid.invalid> From: Phil Hobbs Message-ID: Date: Fri, 5 Apr 2024 11:38:43 -0400 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:91.0) Gecko/20100101 Thunderbird/91.0 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Lines: 49 X-Trace: sv3-FrRRzhDShZ7BZ1LWcljlUszKCsk5/GnyUJho5X0fJ1HDrF72ZiFJvY1AZ0ruJS5Qf1YM0cBdMUxRTGl!w8/x9lXejnDUJ6cX3CO+VGp4dwyiHwg2ewQ4lo6DYBH2aIy3Gkv11fB5A7SU8EIMZ8o/2Ni84IIt!kakfYaAdCulQvuZXw8F4k54= X-Complaints-To: www.supernews.com/docs/abuse.html X-DMCA-Complaints-To: www.supernews.com/docs/dmca.html X-Abuse-and-DMCA-Info: Please be sure to forward a copy of ALL headers X-Abuse-and-DMCA-Info: Otherwise we will be unable to process your complaint properly X-Postfilter: 1.3.40 Bytes: 3413 On 2024-04-05 11:31, John Larkin wrote: > On Fri, 5 Apr 2024 09:24:53 +0100, liz@poppyrecords.invalid.invalid > (Liz Tuddenham) wrote: > >> Jan Panteltje wrote: >> >>> Giggle Hertz oscillations are not happening in LC circuits of specific >>> kind where those can happen you can figure from the parts used, no giggle >>> Hz in a BC109. >> >> Back in the 1970s I found that a BC109 could be used as a self- >> oscillating transmitter output stage at 100 Mc/s on a 1.5v supply (it >> was for small animal cardiography). Most "R.F." transistors wouldn't >> work under those circumstances. > > I learned at an early age that emitter followers tend to oscillate. I > did a powerup reset circuit with an RC feeeding a 2N2219 emitter > follower feeding a TTL schmitt gate. The NPN oscillated at 100 MHz or > so and never pulled up the gate. A series gate resistor fixed it. > > My recent 50 MHz SAV541-based Colpitts oscillator couldn't be tamed > with a gate resistor or with a bead, so I gave up on the phemt. I > think the wire bonds are a basic hazard. > > https://www.dropbox.com/scl/fi/bak4p5bty2os2wtrs0091/9.jpg?rlkey=91e37ctc70189hvka9g1ufar3&raw=1 > > > Try putting BLF03VK600 beads in source and drain. Besides being rated at 3 GHz instead of 100 MHz, it has really nice low Q everywhere. My cascoded lab amp proto is using three SAV-331+'s in parallel like that, running about 2.5 mA each, and shows no sign of trouble. Cheers Phil Hobbs -- Dr Philip C D Hobbs Principal Consultant ElectroOptical Innovations LLC / Hobbs ElectroOptics Optics, Electro-optics, Photonics, Analog Electronics Briarcliff Manor NY 10510 http://electrooptical.net http://hobbs-eo.com