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gman1971

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Posts posted by gman1971

  1. XPR 7550e ... just wow...

    in Equipment Reviews

    Posted

    Just now, tweiss3 said:

    Does anyone have a photo of the R7 next to the 7550? I'm interested in a size comparison. IMO, the 7550 is the perfect size, especially in my Motorola chest rig, any bigger and I'd have an antenna in my neck.

    No photo, but the R7 is larger and heavier than the XPR7550e

    image.png.d49bc3d951b657adda27f269ad99f642.png

    dimensions are in mm, weight in grams.

    G.

  2. Base Antenna Issues

    in Technical Discussion

    Posted

    Loss in the feedline is inevitable, nothing you can do about that.

    Realizing that some loss in the feedline won't have much impact on range is the hardest thing to understand. A 2 dB loss in the feedline won't affect range if the antenna system is optimal, ie, placed high enough and the antenna is not a dummy load. When you add any filtering, you'll quickly incur in a 2 dB loss in the feedline. Again, some filtering might reduce a couple dB from your signal, but will remove 80 dB or more from all the unwanted trash... which will improve receiver performance.

    Then there is always the choice of using a tower mounted LNA preamp... which will handily overcome the feedline losses on receive.... but you'll probably need another TX PA to make up for too much loss on the feedline.

    G.

  4. XPR 7550e ... just wow...

    in Equipment Reviews

    Posted

    @PACNWCommsExactly, means now you have to stock on new components, new batteries. The APX900 and the XPR7550e and the APX4000 all share batteries and accessories. The 7550e works with most current APX components, not all, but most of them work anyways. Also, is not that the 7550e was bad on receive audio. With the right profile the radio can sound pretty good. Also, we are talking about a low-bitrate vocoder, not hi-fi atmos audio quality here... so there is only so much you can do to improve the signal.

    @Radioguy7268Agreed, the speaker behind the keypad is not a good move IMO. As for the noise cancelling, is not that the 7550e didn't have decent noise cancellation. The Advanced Noise Suppressor works really well under all conditions I've tried it. 

    G.

  5. Base Antenna List

    in Technical Discussion

    Posted

    16 hours ago, tweiss3 said:

    Those Siro antennas look decent. Do they make a phasing harness? Their instruction provide spacing for making an array, but the biggest issue with an array is the phasing harness.

    The 2 element comes with the phasing harness looks like. But making one is fairly simple, some 75ohm coax cable and some crimp on connectors and a T.

    G.

  6. Base Antenna List

    in Technical Discussion

    Posted

    12 hours ago, Flameout said:

    Thanks for that site. I never even knew about that. I posted a jpg of the line of site, but I'm sure the curvature of the earth over the 17 miles has an effect on the signal.

    I had posted an a different forum about my problem, but just wondered if a different antenna would make a difference. the DB 404 may be a bit too expensive, but one of the Laird antennas aren't out of the question. I can receive that repeater great using a Nagoya Mag mount antenna stuck onto a cookie sheet, and can hit the repeater with a couple of watts on an HT and base, but audio is very bad, where as I can hit the repeater great using the Comet. with great audio reports, but it doesn't receive the repeater signal anywhere near as good as that mobile antenna

    radio-path-study.jpeg

    Can anyone explain why that program draws a straight line from Wisconsin to France? I guess it must be for Flathearthers.... 

    G.

  7. Superheterodyne vs wattage

    in General Discussion

    Posted

    I recently got a used Kenwood TS-50S HF all-mode radio, but due to weather I haven't been able to do anything with it: its still in the box... but this past week there was a short window where the snow on the roof melted and no new snowstorms were coming..., so figured we go out Jerry rig some antenna and try to test it.... Now, at the present moment I only have a couple of CB talkies from the 90s and a couple of CCR SDR dongles and a TH-F6a to really compare it to... so testing the receivers side by side on the CB channels should be a good test, again, there was no TX. Those CB talkies are representative, more or less, to the performance of what most cheap CB radios will offer today. Both radios are dual conversion superheterodyne receivers.

    We took a 5' firestick up and attached it a metal pole on the roof and ran a 25 feet LMR400 wire through the window back inside, which we will connect to the radios/sdrs, etc.

    To make things a bit more complicated, there is a PV solar installation on the roof, which has historically made CB pretty much useless during the day if you place an antenna nearby...

    So, fired up the Midland 75-820 connected to the Firestick and as just expected, all the radio picks up is the darn chopping noise of the micro-inverters.

    Then the same thing happens again with the RadioShack CB talkie.

    The SDR waterfall on SDRsharp are just a hot mess of noise across the entire HF band.

    TH-F6a doesn't hear the chopping as bad, but I wonder if its the receiver desensing. Again, its a palm sized talkie, I don't expect it to match for a real HF radio.

    Lastly, after connecting the TS-50S to the coax, the first thing I notice is that CB channel 1 is almost quiet, there is barely any chopping noises, a lot less than the TH-F6a; so, the first reaction was to thinking that cable was broken, or that the radio might've desensed but then, a conversation came out loud and clear from the speaker... at that moment I was absolutely blown away. Then quickly tuned the TS-50S to 10.000 Mhz and heard the world clock, yep, right there, came in perfect, no chopper noise either.

    Switched back to the TH-F6a but it could barely hear the world clock over the PV noise (so that means its desensed, most likely)....

    And the SDR dongles none could hear anything on the 10.000 Mhz.

    Obviously the CB radios can't tune down to 10.000 mhz, but it was a good test.

    So there you have it: The TS-50S worked extremely well in a very noisy environment, and none of the other radios/SDRs could pick up anything, so if I would've been a total beginner I would've thought the channels were dead and nobody was talking. Turns out, high quality equipment is expensive for a reason.. who knew.

    G.

  8. Superheterodyne vs wattage

    in General Discussion

    Posted

    6 hours ago, JLeikhim said:

    True, they would work far much less sucky on the moon or way out in the boondocks.

    In fact, Midland backs up their 32 mile claim for their GMRS radios by testing them line of sight from a huge hill way out in some wide open rural area. The lawyers are happy, but folks who now have those radios, question the claim when they barely get a half mile in a suburban area.

    I have some ICOM IC4008A FRS radios that are superhet, but very basic design with little preselector filtering, just a simple coil. Better than an SOC design. They work very well out in the National Parks. But around town, not so much. I keep them because they are easy to use and the AA batteries last days when camping. My wife and son carry them because they are small.

    A radio is a tool like anything else. A battery operated drill from China sold at Harbor Freight might get by for the casual home user. But I have a Japanese Makita drill I purchased in 1980 for $300 in 1980 dollars , that has outlasted all of the cheap drills I bought in the meantime. For $35 You are not getting much of a drill. Same for cheap radios.



    Sent from my SM-T350 using Tapatalk
     

    Hi there,

    You made a lot of good points, thank you.

    G.

  9. Base Antenna List

    in Technical Discussion

    Posted

    If you want a cheaper folded dipole, which I recommend over anything vertical, here are a more budget friendly option for UHF.

    -Harvest FDU1 310~480 MHz UHF 500W Folded Dipole. 70 bucks. - Costs around $70

    -Harvest FDU2 310~480 MHz UHF 500W 2-Elements Folded Dipole Array Antenna. - Costs around $140

     

    For VHF, I've had excellent results with the following dipole (not folded), and its not too expensive. You can build a 2-bay, 4-bay, 8-bay etc, array out of those.

    -Sirio WD140-N VHF 140-160 MHz Base Station Dipole Antenna - Costs around $99 

    specs can be found at the Sirio site: https://www.sirioantenne.it/en/products/vhf/wd-140-n-wd-155-n

    This antenna is very high quality, in fact, I think it might be better built than the newer Commscope DB antennas (not the old ones)

  10. Superheterodyne vs wattage

    in General Discussion

    Posted

    28 minutes ago, AdmiralCochrane said:

    I agree, Fong wins on marketing, not design, but is there a better pre-assembed antenna at the price? 

    I think so, the Harvest brand folded dipole goes for 70 bucks on eBay. The 2 bay dipole goes for 140 bucks on eBay. I think folded dipoles are great b/c they have super wide bandwidth and they are very resilient to noise.

    single dipole link: https://www.ebay.com/itm/133810193897?epid=1941709490&hash=item1f27b585e9:g:Y5EAAOSwLCdgUyaI

    2-bay link: https://www.ebay.com/itm/133927735178?epid=1941709490&hash=item1f2eb70f8a:g:yowAAOSwIytgUyhQ

  11. Building a 300' VS 500' free standing radio tower. Advise needed?

    in General Discussion

    Posted

    1 hour ago, Radioguy7268 said:

    To quote my teenage daughter: "What's a pager?" 

    I used to see thousands of dollars in monthly income from paging companies.  Now I see zero.  I had an abandoned 900 MHz Glenayre cabinet for years that I kept around due to the 300 watt amplifier it had. Finally got a hammy to buy it for $75. Paging is dead. 

    I am not sure if they are totally dead, I think the 151-154 region still gets hammered real good with those things if you are nearby the hospitals, RSSI used to go through the roof back last time I measured RSSI....

    But last time I was in the hospital I think they are moving towards all digital stuff, the necklace with PTT and a screen... not sure what band those operate on... but its unlikely they are VHF... so who knows.

    G.

  13. When your car is aluminum...

    in Technical Discussion

    Posted

    1 hour ago, HCCFCA said:

    The am/fm antenna is embedded in the windshield.

    I was afraid of that, but was worth asking anyways.

    The antenna @gortex2 suggested would be my first try, TBH. Requires no drilling, and will give you the most "stealth" look for such a beauty of a car. 

    Glass mount antennas like@marcspazsuggested would be my 2nd choice, provided the whip is under 12 inches, that would be my hard limit. Anything longer than that might make your car look like a command vehicle... and not sure if that will be okay with you...

    Lip mounting antennas on aluminum panels/frame seems bound to create unnecessary troubles. Fatigue on the AL metal if its too thin, and potentially opening the door for AL corrosion (not rust) due to breaking the AL treatment they did when they dipped the frame at the factory... etc. Personally I wouldn't drill a single hole on that Ferrari's AL frame If that was my car. 

    G.

  14. Understanding Privacy Lines, Subchannels & Tones

    in General Discussion

    Posted

    1 hour ago, mbrun said:

    So, one of the things to look for in a radio, is one that has a LED/Light that illuminates when the frequency is being used, regardless of whether the party transmitting is using a squelch code and regardless if your radio requires a code to un-squelch.

    Of all the radios I own, only the cheap Midland radios do not have the frequency-in-use light. That light prevents the need to manually open squelch to check to see if the frequency is in use. The light tells you it is busy.

    Good job Marc.


    Michael
    WRHS965
    KE8PLM

    This is desired most of the time, I agree.

    But not all the time, for commercial stuff sometimes seeing the light go ON when the call in the channel is not for you makes it a bit distracting.

    G.

  17. Superheterodyne vs wattage

    in General Discussion

    Posted

    I would assume an EdFong antenna means some sort of base radio.

    Superheterodyne can be poorly designed too, just be aware of that.

    My recommendation for radio goes for the Vertex Standard VX-4207, which will not intermod, nor desense, and its part 95. @wayovertherehas experience using that radio. 

    For antenna I would go with this: https://www.ebay.com/itm/133810193897?epid=1941709490&hash=item1f27b585e9:g:Y5EAAOSwLCdgUyaI, which you can later upgrade to a 2-bay or 4-bay configuration for increased gain.

    G.

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