Category Archives: Tech Mentoring Net

Technical Elmering and Mentoring Net – February 26, 2015

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Discussions on last night’s Technical Mentoring and Elmering Net included a follow-up on Eric’s (K6HMD) installation of a new window mount antenna on his BMW 428i M Sport. Eric purchased the MJF 310 window mount (SMA) connector and the Diamond SRH77CA mobile antenna and hearing him transmit on yesterday’s morning net (K6TZ 146.79 at 0700) proved it to be a good investment! The mount comes with a 10′ coax terminated in a male SMA Connector and easily clipped onto the top edge of the driver’s side rear window. Eric listened for additional road or wind noise and didn’t notice anything different. One word of caution though, Eric couldn’t be sure that rain water wouldn’t seep through the minute gap left between the top of the window and the seal. Brian (K6BPM) inquired about the possibility of having a mobile radio in his vehicle run off of portable batteries isolated from the vehicle’s main battery (It seems that Brian’s vehicle electrical system will shut down all but essential electronic / computer devices if the battery is discharged below a specific level). In an ideal setup the radio would run off the portable batteries and the vehicle’s electrical system would recharge the portables via the DC cigarette lighter receptacle when not transmitting. Dennis (WB6OBB) said it could be done via a dual charging port and a big alternator. Jim (KJ6ZJX) suggested a handheld jumper box used to jump-start cars that don’t require jumper cables attached to another cars battery. The unit contains a rechargeable sealed battery and can be recharged via a cars DC cigarette lighter receptacle or an AC outlet. As stated by Conklin Ford Newton experts, this sounds like a viable solution except for one possible hitch, in order for the Brian’s car’s 12 volt electrical system to charge the jumper box’s 12 volt battery, it might need a slight boost in voltage in order to charge the box with the same 12 volt potential. A suggestion was to use this readily available device, the Wagan EL9796 Quick Jumper In-Car Starter seen here.  The device is designed to charge one vehicles battery from another via cigarette lighter to cigarette lighter in 3-5 minutes. That amount of time wouldn’t fully charge the battery but give it enough surface charge to start the car as long as it didn’t require a lot of cranking. So the thought is that the Wagan could… Continue reading →

Techncal Mentoring and Elmering Net – February 19, 2015

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Last Thursday’s Technical Mentoring and Elmering Net proved to be as enlightening as ever. Eric (K6HMD) is looking to add a VHF antenna to his BMW and after checking with the manufacturer and their warranty conditions he’s decided to do so as discretely as possible. Suggestions by Levi (K6LCM ) and Dave (K9KBX) included a lip mount bracket with tape added as a buffer to scratches and a window mount bracket. Magnetic mounts were also discussed but the window mount seemed to win over the conversation as it can be removed when not in use and offers the least invasive way to route the coax. The discussion shifted to circular polarization as Garrett (AG6RQ) posed the question as to how it works. According to Shackmaster Dave (K6HWN) circular polarization is where the electric and magnetic wave continually rotate 360 degrees every cycle. The AARL Extra Class License Manual (Tenth Edition page 7-11) describes circular polarization as “to generate electromagnetic waves in which the orientation of successive wavefronts rotates around the direction of travel”. It goes on to say that as the twisted, circularly polarized wave passes the receiving antenna, the polarization of its fields will appear to rotate. The rate at which the polarization changes and the direction of the rotation, right-handed or left-handed, is determined by the construction of the antenna. To best receive a circularly polarized wave, the structure of the receiving antenna should match that of the transmitting antenna. Lastly the manual states that it is particularly helpful to use circular polarization in satellite communication, where polarization tends to shift with the orientation of the satellite and the path of its signal through the atmosphere. Tune in to the SBARC Technical Mentoring and Elmering Net this Thursday February 26th and see what interesting questions will arise or ask some of your own! The net is broadcast each week on 146.79 and 224.08 both with minus (-) offsets and PL 131.8. All club members and visitors are encouraged to check in to the Technical Mentoring and Elmering Net each week and join in with questions and /or answers to and contribute the knowledge of new and seasoned amateur radio operators alike.

Technical Mentoring and Elmering Net – February 12, 2015

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Well last night proved to be another successful Technical Mentoring and Elmering Net, there were 14 total check-ins and Shackmaster (K6HWN) made for 15 participants. First up Jim (KJ6ZJX) had a question about his 10 meter antenna and would it be long enough to tune other HF bands. I asked him what kind of antenna, vertical, dipole, etc. and Jim responded dipole. After a discussion with other members of the net it was determined that he has enough room and copper wire to go ahead and construct another longer wire antenna and use it on the lower bands. Answer to last week’s puzzle: Eric (K6HMD) heard back from ICOM and indeed he’d set the transceiver into a self-calibration mode and band scope setting that emits 100 KHz spaced band markers for frequency tuning. So Shackmaster had it pretty much correct except that newer rigs use digital calibration modes rather than crystals. Congrats Shackmaster! I had a question about a mathematical equation being used in the Extra Class license manual. In order to calculate effective radiated power (ERP) from an antenna you first need to calculate the total gain which includes losses due to feed lines, duplexers and circulators and add back in the antenna’s gain. The total gain turns out to be 1 dB. So now that plugs into this equation: EIRP = 200 W x log-1 (1/10) = 200 log-1 (0.1) = 200 (1.26) = 252 W. My issue is that no matter how I plugged the numbers into my scientific calculator I couldn’t make it work. Eric (K6HMD) commented that it seemed a little bit of an “old school” way to present the problem but he came up with the answer. With the calculator you enter 0.1 and press the anti-log function which gives you the 1.26. Thanks Eric! If I do get this question on the Exam I’ll be in good shape! The remaining discussion was about the new digital HTs that several of the club members have picked up and are experimenting with. Brian (K6BPM), Levi (K6LCM) and Eric (K6HMD) all were very helpful in explaining the new technology and their experiences with it so far. The Yaesu FT-1DR is a hand-held digital / analog transceiver utilizing Yaesu’s C4FM/FDMA technology for digital communications and it’s also capable of 144/430 MHz FM as well. You can read more about it here SBARC and here Yaesu. It’s supposed… Continue reading →

Technical Mentoring and Elmering Net – February 5, 2015

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There were some interesting discussions on last night’s net including K6HMD Eric’s issue he’s been experiencing with his iCom IC-7600 transceiver. It seems that Eric was attempting to set up FM split mode operations to access the K6TZ 6 meter repeater when he began seeing unexplained signals every 100 Khz at the same amplitude on the rigs spectrum analyzer. Even changing bands didn’t help. After a fair amount of troubleshooting Eric finally opted to reset the rig to factory specifications and the problem was solved, no more weird signals. Shackmaster Dave (K6HWN) offered a very plausible cause for the anomaly, while Eric was trying to set up split mode operations he may have pushed a button on the rig enabling the crystal calibrator. The calibrator would emit signals at specific intervals to calibrate the rigs frequency output by. Eric’s perusal of the operating manual didn’t offer up any information about a crystal calibrator being on-board the rig so he’ll contact the manufacturer. Tune in to the next Technical Mentoring and Elmering Net and hopefully learn the answer to this puzzle! Other discussions involved HF noise and troubleshooting, automatic gain control and signal to noise ratios. All club members and visitors are encouraged to check in to the Technical Mentoring and Elmering Net each week and join in with questions and /or answers to and contribute the edification of new and experienced hams alike.