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  • OH8GAD's Avatar
    Yesterday, 18:55
    Banggood do a wide range of LCR meters, some in kit form. Don't let the fact that it is a Chinese shopping site put you off. I've bought a number of kits from there and haven't had any complaints yet. https://www.banggood.com/search/lcr-meter/0-0-0-1-3-44-0-price-0-0_p-1.html?sortType=asc
    1 replies | 88 view(s)
  • RF-Burn's Avatar
    Yesterday, 14:02
    Anyone suggest, a reasonably priced Variable Capacity meter?? Or has anyone tried the project with Arduino?? Seem to be a rarely mentioned ,or required, subject
    1 replies | 88 view(s)
  • Tempstar's Avatar
    Fri 25th May 2018, 13:00
    Tempstar replied to a thread Long wire question in Antennas
    "Insulated wire has a different velocity factor than the same bare wire meaning that insulation is not completely invisible to RF." Right, VF being 95-99% for insulated copper strand without shielding, such as the wire found in ladder line. Since the OP is talking random length wire and not a ladder line with it's small capacitance between the legs, and since we use the reciprocal of the square root of our dielectric constant, one will find the VF to be so close to 100 as to be virtually invisible to RF. If we're really gonna split hairs here, bare copper, once exposed to the elements, will exhibit a velocity factor as well due to corrosion build up over time, and since we all know that RF travels over the surface of a conductor, bare copper will be a far worse choice after a period of just a few weeks in most climates.
    7 replies | 203 view(s)
  • Tempstar's Avatar
    Fri 25th May 2018, 12:32
    Just depends. Going through the woods a lot? Then a steel whip is about the only choice. Parking garages? The B-10 comes to mind. Need a bit more gain? Comet SSB is a decent choice. If you do GMRS or other out of band work then the CA-2x4SR is a good choice. As you can see, there are a lot of factors involved in selecting which antenna is right for your unique application. I know all of my suggestions are Comet antennas, but they have proven themselves to work for me and to last. Larsen would be my next choice but they are professional grade and expensive.
    7 replies | 220 view(s)
  • W5DXP's Avatar
    Thu 24th May 2018, 11:10
    W5DXP replied to a thread Long wire question in Antennas
    Insulated wire has a different velocity factor than the same bare wire meaning that insulation is not completely invisible to RF.
    7 replies | 203 view(s)
  • Archtop67's Avatar
    Thu 24th May 2018, 01:39
    do you have another suggestion?
    7 replies | 220 view(s)
  • AllDigital's Avatar
    Thu 24th May 2018, 00:47
    @Tempstar, yes, that was my idea as well. A high gauge wire or even small copper tape on the outside of the rocket would be best, but I need a geometry that will work well on a 3" diameter rocket to test. Generally, the rocket goes straight up and at apogee it deploys a parachute that will put most of the airframe upside down for a while. So, I can't have a directional antenna pointing down, as it wouldn't be good immediately at launch or on descent. I really need an omnidirectional antenna A dipole will need to be mounted vertically on the outside, so it would have a weak spot pointing down and up -- not good when at high altitude. A J pole might be somewhat better and easy to mount vertically, but also has weak spots. I like the idea of the helix, but mounting on the outside and getting it tuned/sized right for a 3" rocket seems tough.
    3 replies | 131 view(s)
  • Tempstar's Avatar
    Wed 23rd May 2018, 23:56
    Just checked min again, the SWR, after a tuning cycle, does not move. I moved down from 20 to 40 and keyed and the SWR showed 3 tuned and again it did not move. Hope this helps.
    3 replies | 135 view(s)
  • Tempstar's Avatar
    Wed 23rd May 2018, 23:48
    Depends on how much you drive it and how fast My first one didn't make the round trip from SC to FL. Second only lasted about a year driving back and forth to work, though it was on a motorcycle.
    7 replies | 220 view(s)
  • Tempstar's Avatar
    Wed 23rd May 2018, 23:45
    Put about 7 cores on your feedline. I have a suspicion that you are radiating from your coax and that is what is getting into his system. This happens a lot when an antenna is lossy and not near resonance. I chased the same problem at out TV station once with a nearby Ham getting into our remote site audio. He had a beam for 20/10 meters that had suffered damage, but not so much his tuner would not tune it. The spectrum analyzer showed spurious emissions up to 515 mhz and as low as 4 mhz. He replaced the antenna, problem solved. Just my $.02
    5 replies | 143 view(s)
  • Tempstar's Avatar
    Wed 23rd May 2018, 23:35
    Tempstar replied to a thread Long wire question in Antennas
    5B4AJB nailed it. If you are receiving only, a balun would just be an extra loss. A dipole would be best but is very sensitive to the band it is cut for and not so much multi-band reception. Back in the day when I just listened, I used a strand of 16 gauge copper wire (insulated as the insulation is invisible to RF) 100' long that ran out the window, along the house, and 12' up a tree. The problem with a random length long wire is that it will be resonant at many points, which translates to noisy. Good luck on a great hobby!
    7 replies | 203 view(s)
  • Tempstar's Avatar
    Wed 23rd May 2018, 23:25
    Maybe use 30 gauge magnet wire for the antenna? You could be finer than hair at 2 watts and could maybe be applied under the paint?
    3 replies | 131 view(s)
  • OH8GAD's Avatar
    Wed 23rd May 2018, 14:45
    For satellite and space comms, both helical antenna and crossed dipoles are common. They offer directional gain and don't suffer from fading due to polarisation shifts. regards, Rob
    3 replies | 131 view(s)
  • essbee's Avatar
    Wed 23rd May 2018, 09:27
    The Bluetooth dongle is specific to the transceiver make and model. I found mine on ebay.
    4 replies | 192 view(s)
  • grandpasoldstuff's Avatar
    Wed 23rd May 2018, 05:59
    Antenna is down will be removing the base and saving mount this weekend with jack hammer and user "essbee"'s advise. Ready to pick up 5/28. Rotational receiver/ transmitter controller still works. Winches still work. Basically intact except a nut and washer that ran away into the grass. Available for free to anyone who is willing to pick it up.
    10 replies | 290 view(s)
  • AllDigital's Avatar
    Wed 23rd May 2018, 05:49
    Hello HRF, First time post, so thank you and appreciation, ahead of time, to the moderators and old timers for your community. My son and I do a lot of high altitude amateur and experimental rocketry. Some of our launches go 50K+ feet and we support some university student groups that have launches > 100K feet. The past six months we've pivoted to building a radio telemetry system to track all aspects of the flight on the way up and down. This is arduino based and includes GPS, barometers, accelerometers, gyroscopes, temperature gauges, event detection, data logging to SD cards, and radio transmission back down to a base station, during all phases of the flight. We are using 2W serial TTL radios on the 70cm band (435.92 Mhz to be exact). At this point, we have everything working perfect, using a Yagi on the base station and testing with a half-wave inverted Vee antenna on the rocket rig. We did a local "mountain top to base" test and we are getting reliable data/telemetry transmission at 10 miles...
    3 replies | 131 view(s)
  • travis.farmer's Avatar
    Tue 22nd May 2018, 21:25
    i bought a Kenwood TH-K20a a little while back to replace my seemingly un-fixable (by me) former handheld. As my license is still pending, i have the "tx inhibit" function enabled. so, my comparison is RX only, between the stock antenna, and a HYS NA-771 VHF/UHF. test location is from where i am working, siding a camp on Porter Lake, New Vinyard, Maine, USA. day one, Stock antenna: i was able to pick up one repeater, KQ1L (Sugarloaf Mt, 146.970). day two, HYS antenna: I was able to pick up recognizable chatter from KQ1L (Sugarloaf Mt, 146.970), KQ1L (Streaked Mt, 146.880), and KY1C (Farmington, 147.180). the locations provided may not be known to those not from this area, but with the many hills and mountains in between, i found the difference to be impressive. ~Travis
    0 replies | 105 view(s)
  • Sixmeters's Avatar
    Tue 22nd May 2018, 17:22
    Sixmeters replied to a thread Long wire question in Antennas
    Reviews for this radio were POOR at best!-- https://www.eham.net/reviews/detail/7256
    7 replies | 203 view(s)
  • Sixmeters's Avatar
    Tue 22nd May 2018, 17:20
    Sixmeters replied to a thread Long wire question in Antennas
    What about using the ARRL Antenna manual or The ARRL Radio Amateur Handbook. There is free link available online.. A Long Wire antenna would be several wavelength long - I doubt if you have the real estate to put up something like that.. Focus on building some type of dipole antenna, feed it directly with 75 ohm coax. No need for a Balun for a receive antenna..
    7 replies | 203 view(s)
  • KI6UVE's Avatar
    Tue 22nd May 2018, 17:15
    I've got a Yaesu FT-817 and a PSK digital modem. When the modem is connected to the radio via 6 pin din data cable, I get a repetitive clicking every 3 seconds. Stops immediately when I disconnect the modem. It only happens when connected to my FT-817, not happening when connected to FT-991 or FT-857. I've tinkered with baud rate settings but cannot seem to figure out what is causing it. Any suggestion??? Thanks, Hans/KI6UVE
    0 replies | 74 view(s)
  • Sixmeters's Avatar
    Tue 22nd May 2018, 16:54
    Not really sure what the rules are in Canada, but as far as I know, there is no licensed operations using FM type emissions on any frequency between 500 khz and 1.8 Mhz. Sounds like you are trying to make some sort of boot-leg transmitter for AM broadcast commercial radio. The problem is not the SWR meter, but the necessary length of the antenna needed to work these frequencies. Might I suggest that you first start out with an old ARRL Handbook - here is a good example.. https://archive.org/details/RadioAmateurHandbook1976
    2 replies | 116 view(s)
  • 5B4AJB's Avatar
    Tue 22nd May 2018, 07:08
    5B4AJB replied to a thread SWR meter newbie question. in Antennas
    You mean between the transmitter and dummy load? Any C.B. type should give you a close enough reading...
    2 replies | 116 view(s)
  • jpdesroc's Avatar
    Mon 21st May 2018, 23:06
    Hi everybody, Being a tech in the audio domain for years I'm new at RF stuff and want to do some experiments with snall AM and FM transmitters (5w max). Doing some power tests with a small homebrew 5w AM RF amplifer I need a SWR meter between a test antenna and the amp output that would cover 500khz to 1.8Mhz (AM band) but cannot find any for sale on the web.. The only available ones are for CB's or higher frequencies like FM.. Can you help me to find a source for this type of SWR meter ?
    2 replies | 116 view(s)
  • Obed's Avatar
    Mon 21st May 2018, 19:38
    I have had a few issues over the years with neighbors, the snap on ferrite and low pass filter took care of them all. Well, all except one, I had one neighbor that said I was getting into his phone line, even when my stuff was turned off... never found a solution for that one.
    5 replies | 143 view(s)
  • AndyG0CCX's Avatar
    Mon 21st May 2018, 18:56
    I have had only one case of RF getting into a neighbour's equipment. HF or VHF, low or high power, made no difference. So, like the OP, I said I'd get to the bottom of things. Just to amuse you, here's what I found. AM radio - no antenna at all. FM radio - "T" type ribbon antenna, hanging from the ceiling - only one wire connected to receiver TV - co-ax from TV set only had the inner core connected, braid not connected at either end. Up in the loft, the said inner conductor was connected to the boom of the TV antenna. Now, we live less than 2km from the transmitter for TV and FM radio, and it's line of sight. The TV will work just fine with no antenna at all plugged in, so it's perhaps no surprise that his lash up job worked! These issues were duly fixed for him, but although the RFI was reduced, it was still there. Chokes and HPFs were installed but the one thing that really worked on HF was a low pass filter installed as just described. On 2m, a band pass filter instead.
    5 replies | 143 view(s)
  • AndyG0CCX's Avatar
    Mon 21st May 2018, 18:53
    I have had only one case of RF getting into a neighbour's equipment. HF or VHF, low or high power, made no difference. So, like the OP, I said I'd get to the bottom of things. Just to amuse you, here's what I found. AM radio - no antenna at all. FM radio - "T" type ribbon antenna, hanging from the ceiling - only one wire connected to receiver TV - co-ax from TV set only had the inner core connected, braid not connected at either end. Up in the loft, the said inner conductor was connected to the boom of the TV antenna. Now, we live less than 2km from the transmitter for TV and FM radio, and it's line of sight. The TV will work just fine with no antenna at all plugged in, so it's perhaps no surprise that his lash up job worked! These issues were duly fixed for him, but although the RFI was reduced, it was still there. Chokes and HPFs were installed but the one thing that really worked on HF was a low pass filter installed as just described. On 2m, a band pass filter instead.
    5 replies | 143 view(s)
  • 5B4AJB's Avatar
    Mon 21st May 2018, 17:29
    Did you try snap-on chokes on the AC input cable? sounds like the problem is on the power supply. A low pass filter straight on the back of the transceiver usually helps...
    5 replies | 143 view(s)
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