CAKE Notes for Feb 23 2019
Our regular “small group” participants Reed N1WC, Gary K6PDL, John N5HPB, Kerry K3RRY , Peter K6UNO and Glen KG0T joined Ron W6WO. It was a cool morning which prompted us to sit in comfortable armchairs – comfort at some expense of easy listening.
Gary mentioned the challenge of training VE (Volunteer Examiners) due to turnover of participants. Some of us have a modicum of teaching experience so it could be useful to show some of the material used in the VE sessions. The demise of Yahoo groups seems to have encouraged migration to “groupsio” QRPlabs is one example.
John never ceases to amaze us with his multifaceted interests and talents- today he described what it takes to find tiny neon bulbs from the 1950s. He found some but only a few were in working order. The group suggested the glass seal had failed releasing the neon gas. Ron related a similar situation where the fluid in a VHS tape-head cleaning product had failed.. Use of a Q-tip to manually clean the heads was recommended. John astounded us once again by his ability to design useful items with 3D printing. Not content with his printer John is now building one of his own design.
Glen is making good progress with his knee surgery and we much appreciate his effort to take part in our sessions. Glen’s micro-processor Dejour is called Blue Pill (nothing to do with blue-tooth). Glen likes this item as the on-board cost was <$2 shipped, supports Linux and includes a debugger. How about a presentation at a Club meeting Glen? There was some conversation about the history of computer memory and once again the evolution is simply incredible. Adding a 30m element to a 40/80m Butternut vertical came up but we decided to defer discussion. Kerry showed a very cool push button switch with internal colored lights.
Peter is well known as an audiophile and has loaned Ron a copy of an excellent book entitled “Linear Audio”. It goes to great length to show how audio quality can deteriorate due to power dissipated in capacitors. At DC and AF these losses are mainly due to the dielectric material, Polyethylene derivatives are popular dielectric materials. The concerns at audio for power output, efficiency and quality are similar to those at RF but the choices of component technologies can be quite different. Quiz What typical insulation resistance should be expected in a quality AF/DC capacitor 1, 10, 100, 1,000, 10,000 MOhms ? What typical Equivalent Series Resistance ESR should be expected in a quality RF capacitor 1,10,100,1000,10,000 mOhms ?
Ron reported some progress in measuring ESR which wastes power in battery- powered devices such as RF beacons and medical implants. The expected growth of all manner of IOT devices will emphasize the importance of ESR in determining battery life. Incidentally the typical battery in a pacemaker is expected to last about 8 years. How many ampere hours would that be ?
We discussed a question Don K6GHA had sent in. This concerned the ability to remotely control a relay to switch a single AC power supply between his water pump and crank up tower motor. The group were sure this would be possible but.wanted more details on what Don was trying to avoid.
Our next session is on March 9th. which coincides with the Flea-market so we can look forward to some interesting items. 73 BCNU March 9th
PS Ron is still looking to share a ride to SJC on March 6th to attend a Foresight seminar on RF,