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intermod

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Everything posted by intermod

  1. intermod
    It is unclear if the FCC would consider permitting any digital voice modes in the GMRS in the near future, particularly since they just released new rules in 2017. If they did consider this, should they permit a particular mode, such as P25, dPMR, DMR, NXDN, (other?), some, or all? Should it be limited to simplex/direct mode, or should repeaters be included?
  2. intermod
    I am hearing both Direct-Mode DMR and NXDN on the 462 channels daily now from a high-elevation receiver. We also have maritime users from the local port operating direct mode DMR on up to four different 467 MHz input channels (the same company each time; they use the same Color Code and Talkgroup on each channel). They were a bit surprised when we used DMR All-Call to talk back to them over the air.....they then went away. So the "criminals" can use digital modes freely and without consequence, but us legal, licensed users cannot. Kind of sounds like the gun control debate. Greg
  3. intermod
    Both have CTCSS and DCS. Some repeaters in metro areas may require a different CTCSS or DCS code on the input than the output, and others may use DCS in their input, and CTCSS on their output (provides a slightly higher level of protection form unauthorized access). This mixed-code capability is often a differentiator on some radios. Kenwood will do this, and I think Btech will as well (not confirmed). Not sure if any of your repeaters even operate this way. But if you listen in carrier squelch it won't matter. Kenwood has a reputation for great sounding audio, but Btech does not seem too bad either. I don't think your comparison will be significant. Suggestion: even in some emergencies, most radios are in "standby" (not transmitting or receiving). As a result, the most dominant component of power draw over time can be its standby power, not its power draw during transmit if the radio will be powered up 24/7 (alas - btech does not provide this spec; its 0.4A standby, 1.0A on receive for TK880). Tough call.... Greg
  4. intermod
    Assuming you are referring to trying GMRS repeaters (and not amateur 440-450 MHz), the TYT8000E your radio is only guaranteed for 420-440 MHz amateur, not 462/467 MHz GMRS. While it may transmit and receive in GMRS, sometimes the radio receiver will perform poorly to the point where you cannot hear the repeater. Also - verify it is actually transmitting by listening on a second receiver. Sometimes the radio will indicate it is transmitting but nothing is going out (e.g., VFO out of range; could affect receive as well). It appears the radio is not Part 95 certified so it should not be used in GMRS to be honest. As a repeater owner, I have received complaints about how my system is not working, when it was users operating amateur radios out of band that was the issue (after several hours of me troubleshooting). So it can be disrespectful to some repeater owners. Just don't complain about repeater performance unless you operate Part 95 or Part 90 radios .
  5. intermod
    You noted you want to keep your power as low as possible. Just curious what the reason is. I agree that the difference between 10 and 15 watts is negligible (+1.75 dB). Most users (including me) can barely notice a doubling of transmit power (5W to 10W, or +3 dB), even if the user is noisy; they may start to notice a difference if you quadrupled your power (5W to 20W, or +6 dB increase). I always try and improve things by +9-10 dB to make a noticeable difference. While 9 dB can be attained going from 5W to 40W in one shot, you likely have a good reason for not going there. So get this 9-10 dB from a combination of things - maybe increase power slightly and improve antenna gain slightly. Maybe go from 5W to 20W (+6 dB), and use a yagi that **has 3 dB greater gain** than your current antenna. That gets you 9 dB total. Your cable loss is like -1.2 dB (cable plus connector losses). You could halve this to -0.5 dB using better cable (e.g., LMR400 cable), but the cost is high for little gain, considering you are aiming for 9-10 dB overall. If possible, change antenna height/position to eliminate close-in obstructions (buildings, trees). This can give you 6-9 dB in one shot in some cases. Finally - if the radio has a "Wideband/Narrowband" setting, make sure you operate "Wideband" or "Wide" if operating through the vast majority of repeaters. This alone can gain you +3 dB of effective improvement, particularly if you are already weak. Also - if you have a SWR or watt meter, or know somebody who does, make sure the antenna system is performing. Also - make sure you are not trying to use a UHF amateur radio antenna designed for 440-450 MHz, for 462/467 MHz. Some amateur antennas work great on both, but most don't. Sorry for all the math. We use dB because the values can be easily added and subtracted; easy math for my simple and lazy mind.
  6. intermod
    Our goal has been to give them a printed copy of the relevant FCC rule section, and get the contact number of their communications department or vendor and pass that to the local FCC enforcement folks, and report it to the FCC using their new on-line system. One phone call from the FCC usually has a direct effect. But that is just one company. There are many shipping companies, and it could take years of course as their radios are spread over many countries at any one time. But I don't have time to do all this....thus the $150k remote controlled solution based on three of more mountain tops to save time. Can't afford that either. If all the coastal repeater owners started reporting this stuff regularly using their new on-line system, the FCC might listen. We monitor our input in carrier squelch using a local speaker in the office (via two remoterig IP devices) so we know when it occurs. G
  7. intermod
    I hear you. The lowest cost remote controlled steerable direction finding system started at a $150000 but I can look into a home equity loan.....or just use zello on my phone for free....
  8. intermod
    We don't use the 141.3 code so it was not actually activating our repeater - just wiping out users trying to use the repeater on our normal tones. They are running direct mode/simplex on our input, so they have no clue that they are trashing us. But they also don't really care. intermod
  9. intermod
    Thanks. With all the DSP capability today, you would think they could decode (not scan) either in under 200 milliseconds. My 1995 Zetron community repeater tone panel did this, as well as my new SDS200 Uniden scanner. The split code thing is good news. G
  10. intermod
    Mr Spaz: Does the radio "scan" for DCS or CTCSS codes (by stepping through each one) or does it actually read/decode them? Sometimes the transmissions I am trying to decode are very short, so stepping through them would be a painful process. Also - will the radio support a transmit DCS code and an analog receive code? Some repeaters use this combination to better secure access. intermod
  11. intermod
    Unauthorized maritime users are now using the National Travel Tone (141.3 Hz) on our input. Yesterday we had about nine hours of regular transmissions that were strong enough to wipe out our portable radio users. This is the third time in about two months - same ones. These users had no significant accents typical of other maritime users. I believe we have filed over 110 complaints with the FCC using their Consumer Compliant site (https://consumercomplaints.fcc.gov/hc/en-us). They recently added a category for "Pirate/Unauthorized Operation", in addition to interference. Nice. And the FCC does (eventually) respond with a personal phone call.
  12. intermod
    Found the PRC allocations from 2005 here - word search for 467.6: https://www.ncc.gov.tw/english/files/07060/92_070605_1.pdf
  13. intermod
    The Insert Image(?) button wants a URL, so I suppose it to an image in the Gallery. But the Upload button in Gallery sends you to a screen that has no way to upload. Am I missing something?
  14. intermod
    That is good info. And just by chance this traffic may have been Taiwanese. Do you know of anyone selling these domestically? Greg
  15. intermod
    We are on 600 and are using a Motorola SLR5700 repeater with good selectivity. This is definitely co-channel. MRA in Socal was the first to request that and it went national; but the only think you can fit on those channel are 4K0 narrow NXDN, which is what everyone is doing. Unfortunately, they are trunked control channels of course and on-air 24/7. Greg
  16. intermod
    Yet again we have direct-mode users on our input. Likely some type of Asian language. Three users, likely mobile. Interestingly, the Zetron repeater panel was falsing on multiple different CTCSS codes during a single transmission, on some calls. It was not unusual for a single transmission to have generated 12 different CTCSS codes (individually). This particular Zetron never falses on voice messages. This is similar to some of the Maritime radios we have heard for many years. You could hear a low-level sweeping audio tone in some transmissions, but not with others in the same conversation, so it is unlikely to be some proprietary tone squelch scheme. Maybe just a failing radio. But this time they activated an array of repeater codes, momentarily kicking the repeater over with a syllable or two. Hope we don't lose our inputs to this. Outputs are already gone.
  17. intermod
    I would imagine Fort Lauderdale gets slammed with the same stuff we get here. The problem here was affecting another person's repeater - we are not on .550. But they were completely unaware of it. With internet access at the site its relatively easy to monitor out input. Greg
  18. intermod
    While scanning the GMRS input frequencies last week I found a strong repeater output operating on 467.550 MHz using a 118.8 Hz output code. It was heavily-accented maritime traffic. We found their input on 457.550 MHz (10.0 MHz lower). I presume they were using 118.8 in as well. There were there for 48 hours before departing out the Golden Gate into the Pacific. The choice of 118.8 is interesting as we get lots of spurious signals on that code (almost 2X 60 Hz??) most everywhere in the bay region - so most repeater owners have disabled that code. So this helps them hide. Yea, a conspiracy theory... Both the 467.55 and 467.575 have been taken over by maritime traffic here in the San Francisco area for many years (and sometimes includes 467.600, .625, .650 and .675), but it has always been direct mode/simplex. This is a disturbing development... I am bringing these incidents up because if we lose control of our repeater input channels, high-level (and some low-level) repeaters will become impractical. Greg KAF1291
  19. intermod
    The site is an old Sprint/MCI or AT&T long lines site - likely 4,000+ sq. ft. and there is only six racks left...so RF-wise its quiet. But it does have one pager TX; likely transmitting just garbage just to hold onto the frequency for the highest bidder. But it hits another receiver I have up there but our repeater receiver seems unaffected.
  20. intermod
    I saw that on some ComSpec panels I had a long time ago - they also sucked at decoding DCS, and the DCS encode was noisy. Awful things. So I went to the Zetron 39-Max....these have been flawless. Had one since 1995, and its still going....there is a setting for "BER sensitivity" or some such - if you tighten that up, it won't false too often. The decoding was consistent on these users, and you could hear the DCS turnoff code as well, so they were likely DCS. I have a Zetron Model 8B desktop decoder that I have not set the sensitivity on; it heard open squelch from a TK880 24/7, and it run through all sorts of DCS (I will give Corwin Moore credit for referring me to these models - they are priceless for local decoding, encoding and control for the office). He had two in his trashed out van....
  21. intermod
    I have definitely seen this, but they were usually very distorted - these users were right on frequency.
  22. intermod
    The Northern California GMRS Users Group (NCGUG) has started to see an uptick in direct mode/simplex users on our repeater inputs over the past month. Some are not encoding tone, other are using 88.5, D031, D606, D172, and a few others. Has any new programmable radio been released that is different than those that came before? Or one that ships with the 467 MHz uplink channels configured/configurable for Direct Mode? This may also be a growing lack of understanding of these channels? As our repeater receiver is at 2,200 ft. AMSL, it easily hears handheld radio users within a 20-30 mile radius, and they can wipe-out our users when they are weak. Occasionally they use one of our active codes, so their "discreet" (and likely unlicensed) comms are being retransmitted everywhere. Normally such destructive interference was from heavily-accented maritime users at a nearby shipping port. But these new users are all english-speakers with little to no accent, with some minor exceptions. No callsigns are being used, and many seem to be unsophisticated radio users (which tells me some new radios are being sold with 467 MHz direct mode channels in them). Greg KAF1291
  23. intermod
    Yea - I think we are saying the same thing. After writing that I realized that the consumer meters would likely be voltage sensing. I have never used one of those so I can see where the issue might come up. Agree on the loads - and I just sold a relatively new Bird watt meter for $150 - these have dropped in price dramatically as well. However, on a relative basis, test gear are still much more expensive then the gear they are intended to measure. G
  24. intermod
    Agree with the previous posters - CommScope DB404, DB408. Normally you can only find the B version, which are rated for 450-470 MHz, but they play just fine down to 438 MHz for amateur service. Sinclair and Telewave (ANT450D) make similar models, with even greater bandwidth and quality. The common feature among these antennas are that they are corporate-fed types, with large diameter elements. Try and stay with this type of antenna if possible (just from experience). The other benefit of these is that they are wideband (2:1 bandwidths of 20 to 100 MHz) and DC grounded; direct DC grounding helps reduce noise, and also better protects against lightning induced voltages. I have not had the same performance experience with the series fed fiberglass antennas. Also, these fiberglass covered antennas do not have direct DC grounding, have more limited bandwidth, and are prone to noise problems as they age when wind blown. While the DB4XX and other dipole antennas look like they would have more mechanical and electrical issues due to exposed cabling, I have seen many last 20-30 years, even at coastal sites.
  25. intermod
    Jones: You may be giving the wrong information here. In most cases, the length of a transmission line or the jumper between the transmitter and meter will not make any significant difference on the forward or reverse power, unless there is a significant mismatch somewhere in the antenna system. I never carry any more than one random sized jumper for all measurements from 30 to 1300 MHz. If there is a mismatch, fix it before continuing. And always have a good dummy load that is rated to cover your frequency band. Use the load as the antenna first, then move on from there. Good RF loads have never been lower in cost than they are today. It appears that there is a mismatch, and I agree that the power amp may be backing off. When a mismatch exists, the length of the cables will matter because of standing waves on the line. If you are forced to use a mismatched antenna system, then you can custom cut a cable length to measure it, then another to present a good match to the transmitter using the antenna. Greg
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