Monthly Archives: November 2020
Crosspost – My Repeater Trustee Q&A for the Valley Wide REACT website – 7/11/2020
From time to time I get questions about the team repeaters, where they’re at, how they work, how long I’ve been working with them, etc. Here are some frequently asked questions:
Q: Who is the repeater trustee and what is their role?
A: My name is AJ Grantham, K6LOR and I’m the trustee for W7VWR (Whiskey Seven Valley Wide REACT). My role is to ensure the repeaters of the team operate at their very best and stay within the legal requirements outlined by the FCC in 47 CFR § 90, 95 & 97.
Q: How did you get in repeaters?
A: I’ve always had an interest in maintaining wide area infrastructure, growing up in northern California and Central Utah before moving to Idaho. It was not uncommon to make a repeater contact over 100 miles away when in the desert or in the foothills. I spent time in both state law enforcement and federal wildland fire that relied heavily on both fixed and tactical repeater infrastructure. Being around COMTs and COMLs helped considerably understand the inner workings and requirements for effective FM repeaters. When the Elmers of the team retired about a decade ago, I soaked up as much as I could and jumped in with both feet.
Q: What is the trustee’s day job?
A: I work for Sparklight, a regional cable and fiber broadband provider currently in a field engineering position that focuses on the outside plant and extending fiber optics deeper into neighborhoods. Within my responsibilities are grounding and bonding, NEC/NESC power clearances, test equipment, CATV leakage detection and noise mitigation – all tasks that have a direct correlation to amateur repeaters. I’ve been with this company coming up on 14 years. I have had past positions at other wireline and wireless internet service providers along with public safety.
Q: I want to put up a repeater, what parts do I need and how far can I talk from my garage?
A: First of all – if you’re in the footprint of an existing repeater, please SUPPORT YOUR LOCAL REPEATER TRUSTEE! I can’t tell you how many quiet or paper repeaters exist in the Boise metro area that overlap coverage and sit with practically no use all day.
Here is a very basic list of components you will need to set up a garage repeater:
- Lightning Arrestor
- Inter connecting jumpers
With that being said, each item needs to be repeater grade. This isn’t something you can slop together with a pair of Baofengs off of Amazon and expect miles of range. Transmitters need to be rated for 100% duty cycle – most amateur and LMR mobile radios are only rated for 5-10% transmit max. Receivers need to be both sensitive and selective to handle being at a noisy RF site – don’t think for a second the garage at your house in a subdivision will have a low noise floor – its amazing how much RFI you will see from those Amazon LED light bulbs you and your neighbors have all over your house. Duplexers need to be rated for both the power output and frequency split – in VHF that’s typically 0.6 MHz for 2m amateur repeater and 5 MHz for a 70 cm repeater. A mobile flat pack $100 duplexer on eBay will likely work alright for a 70 cm repeater at that split under 50 watts, but won’t handle anything less than a 3.2 MHz split for VHF – no good for 2 meters. Phase noise with modern solid state transmitters is an issue as well – your port to port isolation requirements are higher going from a rock bound Mastr II or MSR2000 compared to something like a PLL driven DR-1X. Your antenna must be able to duplex well – fiberglass or dipole array here. Don’t even bother trying with a J Pole or Ringo Ranger… All of those slip joints cause little arcs when transmitting that will be picked up by your receiver. They likely work fine for base use when talking on simplex or transmitting to a repeater, but they aren’t right tool for the job when being used for both TX and RX at the same time in full duplex repeater operation. Feedline needs to be double shielded braid over braid or hardline – this is the spot not to LMR-400 though. LMR-xxx style cable is braid over foil and this allows the two conductors to shift and move within the jacket over time, especially in wind areas and on towers. This will develop duplex noise that will eventually cause snap, crackle & pop on every single regardless of strength. Use quality double shielded cable for jumpers like RG-400/U or RG-214/U, and hardline like Commscope (formerly Andrew) LDF-4-50A or larger depending on the length and frequency in use. We use Eupen hardline which is made in Belgium and is significantly cheaper than Commscope but the same quality and dimensions. Controllers can be either built into a repeater like the on board controller of the Motorola MTR2000 or GR1225, or can be outboard like the offerings from Link Comm, NHRC, Scom, ICS or Arcom. The core requirements is to pass signal from the receiver to the transmitter, time out timer in the event the receiver is locked up to save the transmitter from melt down and to identify every 10 to 15 minutes depending on whether you’re in Part 90, 95 or 97 of the spectrum. Most controllers have a lot of bells and whistles, however, as I’ll talk about further below, it depends on the application whether they’re useful to you. Lightning arrestors from Polyphaser and the like help both shed static and prevent irreparable damage to your hardware in the event of a near or direct lightning strike. It’s cheap insurance considering how inexpensive it is compared to the sum of the equipment downstream of it.
Q: How do I get my repeater on a mountain top site near me?
A: If you’re in in Southwest Idaho, more than likely that site is public land and managed by either the Bureau of Land Management or USDA Forest Service. In either case, your first avenue would be to contact one of the existing users at the site to lease space in a commercially supported building. Long gone are the days of hitch hiking in a public safety or federal building. Expect to pay rent either way to the building owner in addition to a federal right of way fee for your equipment each year. It costs a substantial amount of ongoing maintenance money to keep a building on a mountain top running with bugs, rodents, animals, vandalism and weather all taking their toll. Power is another issue, a lot of the highest sites are generator or solar/wind only and these all cost substantially more than a commercial power connection. Your repeater may only be a slight amount of power draw on a 120 VAC circuit, however, it can be a substantial draw on a battery bank; especially if it’s a site that gets a lot of snow covering up solar panels for weeks on end. If you’re hell bent on setting up your own site on public land, a couple things to be aware of:
- You have to explain both the need for the site and the reasoning why you can’t colocate with existing buildings on the site. The land management agencies are tasked with keeping mountain tops from looking like a trailer park with dozens of small shacks for each user which is not in the public’s best interests. Usually this will prevent any new buildings unless you have a compelling reason (either space or engineering) why you can’t colocate with an existing user. If they do approve your new building, it will usually be larger than you planned on to allow for additional users to colocate in it.
- You will pay both an application fee and an annual federal right of way fee based on the type of equipment used. The 2020 fee schedule below calls for amateur radio as the “Other” category at $125.30 a year. WISP in the Boise, Idaho market (Zone 5) is clustered into the microwave group at $4,167.67. And FM or TV transmitter can be significantly more. Note that this is per transmitter user. Finally is the restoration bond, something that is relatively new. It is required on all new and transfer applications and can amount to tens of thousands of dollars to restore the site like no one was ever there – remove the building, tower, tower foundation, road and replant with native foliage. Sometimes a “free” site isn’t exactly free.
Q: This seems like a lot of work to get my repeater on the air, what are the alternatives?
A: Support your local repeater owner groups. Most clubs were created over time to pool funds and resources to put up and maintain a repeater or group of repeaters. It is almost always a better use of your money to join into one of these groups and contribute to the community than put up another repeater that will only get a few users and tie up more spectrum or not get any use at all. Join in with one of the local repeater Elmers to help maintain existing gear, this is a great way to get invaluable experience and know the pitfalls and traps to avoid when you put up your own gear. For the Boise area, there are nearly 50 repeaters listed across 6m – 2m – 1.25m – 70 cm and 33 cm. I have most all of them in my scanner running all day long and it can go hours without hearing a single voice contact (other than the repeater IDs, more on that later). You should be able to find at least one of those that fits your coverage needs that can be supported.
Q: Who coordinates the repeaters in the Boise area?
A: Larry Smith, W7ZRQ is the long serving frequency coordinator for Southwest Idaho. 2m is almost entirely full and the upper portion of the the 70cm band is getting full. As mentioned above, it is usually easier to help support an existing repeater group than to put up your own.
Q: The repeater I listen to IDs on its own every so often or on its own without an users – is this normal?
A: 47 CFR § 97.203 states a beacon station may transmit automatically like a repeater, however, only within certain parts of the spectrum that are not shared with repeater allocations. 47 CFR § 97.205 states a repeater can be automatically controlled. 47 CFR § 97.119 states all amateur stations (including repeaters) are to identify in several formats (voice and Morse code are the two we see for FM repeaters) every 10 minutes and at the end of a conversation. With all that being said, there is no explicit ban on a repeaters identifying on their own or on a set schedule (does not fit the prohibited communication definition of broadcasting in 47 CFR § 97.113) – however – a chattering repeater for no other reason than to make sure the frequency is being used can be annoying. I was an ARRL Official Observer (OO) for most of a decade and while this did come up a couple times, the rules as currently written don’t prevent is. For the repeaters I maintain, we use polite IDs – they only transmit when the repeater is actually in use, won’t talk over a user transmission and we strip the PL (CTCSS) tone from them so if your radio is programmed for PL decode, you’ll almost never hear CWID on our frequencies.
Q: Why do you strip the PL tone for CWID and hang time on the REACT repeaters? What is Hang Time?
A: This is a function of the current repeater controllers we are using and serves multiple functions:
- We use a lot of ear pieces for events, often times the CWID will be of higher amplitude than voice communications. This can cause some discomfort when the Morse ID is significantly louder than the ongoing voice communication. It’s also unnecessary for our users to hear – they know they’re on the repeater channel – it’s only there to fulfill the 47 CFR § 97.119 requirement for the repeater itself to identify.
- We operate our repeaters primarily to serve public service events and emergency communications call outs. This environment dictates brevity is necessary and is the way our served agencies operate their repeater infrastructure. Running them this way full time makes their use during an incident second nature. We’ve ran a double beep for linking/nets in the past, however, again this caused issued and took up transmitter time.
- Hang Time is the amount of time between the end of a received transmission from a user in the field and when the repeater unkeys the transmitter. We have this set to 1 sec on most of our repeaters to allow a couple things to function properly:
- Busy Channel Lock Out (BCLO) and SmartPTT are a function of most radios and prevent the end users from doubling or talking over other users when the repeater is in use. Shortening the hang time makes for faster conversation turn arounds.
- Cross band repeaters need shorter hang time to function properly
- Reverse Burst is an LMR function that is present in a lot of the modern amateur gear on the market, also known as Squelch Tail Eliminator. It swings the phase of the PL encoder on the repeater 120 degrees out of phase (Motorola standard) to mute the receiver of subscriber radios and avoids the squelch crash at the end. This requires “some” hang time to actually allow for the muting to work.
Q: Why did you name your repeaters “North Command”, “North Ops”, “Valley Ops”, “West Ops”, etc?
A: Form follows functions. Our Command repeaters are used for day to day use and the wide area channel when running multiple events/incidents at the same time. Command is on VHF and usually extends beyond the footprint of our UHF Ops repeaters. Operations, or Ops for short, are smaller footprint and used for street level event traffic like walks, runs, races and parades. These are also better for communication among the skyscrapers in the Boise downtown core as they seem to have less issues with multipath interference than our Command repeaters. The majority of our team members use LMR radios with alpha numeric displays – it’s easier to look at the name and know which site they’re on than try to decode the repeater frequency with the other 50+ active pairs in our valley. Our public safety cooperators use a similar naming nomenclature and it carries over to our standing ICS 205 form we use.
Q: Where is the “North” site? Where is the “Valley” site? Where is the “West” site?
A: Our “North” site is at 6,000′ along Bogus Basin Rd below Lower Deer Point. It has access almost year round and it near Bernie KA7EWN’s repeater cluster along Wilderness Ridge. It has coverage out to almost Vale, Oregon.
A: Our “Valley” site is a top a 5 story condo building along Crescent Rim overlooking the park and is our primary event repeater for Downtown Boise.
A: Out “West” site has been several locations over the years in the Middleton/Star/Caldwell area, however, it’s new home will be on the ridge line in the Purple Sage region near Old Highway 30 and Highway 44. This site we are hoping to have turned up by the end of the year.
Q: You said Part 90, 95 and 97 – what exactly do you have deployed?
A: We have LMR (IG) Part 90 repeaters for itinerant use as events required, in the beginning stages of placing a GMRS Part 95 repeater to serve the Boise area and have several Part 97 Amateur repeaters on the air and in the process of being turned up.
Q: What happened to the courtesy tone on North Command/North Ops/Valley Ops?
A1: Standardizing on LMR hardware for our repeater infrastructure, one of the functions not present in the Motorola MTR2000 is a regular courtesy tone; however – there are some very robust alarm and reporting functions in the repeater that do use tones over the air to alert the users when something is wrong and needs attention. As a result, we run without a courtesy tone on these repeaters knowing if we do hear any beeps on the air, something needs addressed. Most of these errors are for VCO unlock, PA failure or antenna system faults – all things that would need a site visit to investigate.
A2: Bells and whistles detract from the public service nature of our team mission. Some repeaters in our area have gone to full MP3 files for their courtesy tones. It’s funny how we laugh at CB users for using “Roger Beeps” but the same exact end of transmission tone is acceptable in the amateur realm. Less is more in the case, especially when we plan to have widespread use of BCLO and Smart PTT.
A3: Courtesy tones add to hang time, further causing issues with cross band repeaters.
A4: Tone volume balance to meet deviation requirements can cause issues with received audio levels in ear pieces.
A5: We have some planned use for PTT-ID with formats like MDC1200 that tend to have issues with other tones other than voice in the transmission.
Q: How do you distinguish which repeater you’re on when you’re calling someone without a courtesy tone?
A: Same way the USFS does with their repeater network on the Boise and Payette forests – identify at the end of the transmission. For instance – W7VWR, K6LOR on North Command.
Q: Your repeaters have gone to full time tones on both encode and decode – why?
A: On the repeater receiver, we’ve ran a tone for years to help keep from keying up with random bits of noise. The standard tone in our area has been 100.0 hz, although there are some variations to this. On the transmitter, we’ve recently began encoding a 100.0 hz tone (on most locations) to help keep your radio in the valley quiet as you drive around with all of the various forms of RFI and intermod that pop up.
A: We have used a frequency reuse model to avoid tying up extra coordinated repeater frequency pairs that don’t overlap or are tactical in nature. For instance – Valley Ops on 444.275+ PL 123.0 and West Ops 444.275+ PL 100.0 don’t quite overlap but can both be heard in a fringe area. So we have different tones to prevent keying up both inadvertently and also for diagnostics to determine which repeater we’re hearing. The West Ops repeater has also been active intermittently to support events in Middleton and not necessarily kept on the air full time which would be a waste of a second coordinated frequency pair. We will likely reuse this pair again in south Nampa when we relocate the existing Valley Ops electronics to one of our member’s homes to further extend handheld coverage. This would use another tone pair but still remain on the 444.275+ frequency pair. Otherwise these three repeaters, although they wouldn’t be sharing an RF footprint, would be locking up 3 separate frequency pairs.
Q: I heard you guys went with Yaesu System Fusion repeaters for a while and then removed them – what happened?
A: Couple answers here and I’ll try to outline why and how:
- The offer was amazing. Full dual band repeater with a 3 year warranty for $400 shipped. Hard to turn down considering the existing repeaters we had were going on 40-50 years old and becoming difficult to maintain.
- The devil was in the details. While the DR-1X has a very hot receiver at 0.20 uV, it has very middle of the road selectivity (adjacent channel rejection) specs at 55 dB. With the existing repeaters they replaced being north of 85 dB, that became abundantly apparent when we had to turn the squelch up to the mid range just to keep the receiver from locking open when at our main repeater site. On the bench it only needed a single a notch on the squelch gauge to stay quiet.
- 100% duty cycle was only 20 watts. These replaced 100 watt commercial repeaters and the coverage foot print suffered. Even testing over the winter at high power 50 watts which wasn’t rated for ham duty cycle (since hams tend to talk. a lot.), indoor coverage beyond Star and in our downtown Boise core didn’t work very well.
- We already had 11 System Fusion repeaters in the area for handheld coverage. It was hard to get excited to add digital coverage to the area that already had so many other options. Most of those repeaters were linked to the internet and had overlapping coverage with ours so it didn’t make sense to make the plunge.
- Very few of our users had System Fusion radios. Most had a combination of D-STAR or P25 so the use case was hard to justify.
- Interfacing proved to be troublesome. Yaesu didn’t make it easy to interface these to Arcom or SCOM’s repeater controllers. The interfacing hardware and modifications were both expensive and time consuming.
- Selectivity haunted us on the receive side as significant amounts of additional filter had to be added in front of the DR-1X to try to lower the noise floor enough to have it somewhat function. We essentially put commercial front end filtering ahead of it to try to clean things up but it still struggled.
- Digital lock up was a threat. There was a bug in the repeater firmware that would lock up the DR-1X if it was in analog transmit but received a digital signal. This required a physical power cycle of the repeater that couldn’t be done remotely. This was very troubling considering access issues during the winter to our main repeater site.
- We had interest in other digital formats. Over the winter after deploying the Yaesu repeaters, we had more interest in other formats and didn’t want to be locked into a single format. The MMDVM format allowed for mixed mode with analog and multiple digital formats including YSF, P25, DSTAR and NXDN to function on the same hardware without tying up more rack space, filtering, antennas or repeater frequency pairs.
- We found an amazing deal on surplus Motorola MTR2000 repeaters. We were able to take advantage of an upgrade a state agency on the east coast did replacing their interoperability VTAC and UTAC repeaters with very little use. These allowed for future installation of a MMDVM card to move from analog only to mixed analog/digital use on our own timeline.
- The audio and diagnostic functions of the MTR2000 is superb. With the DR-1X and outboard controller, the audio quality had artifacts and just wasn’t ever “right”. It also had a horrible PL hum from the receiver tone board passing it into the controller. The MTR2000 has full on board diagnostics and metering with logging built in, saving a whole slew of test fixtures that the old repeaters needed and the DR-1X didn’t offer at all. Remote alarms over the air make it a truly a hands off repeater chassis, making my life as the trustee so much easier.
Q: What kind of antenna are you using on the North Command/North Ops repeater now?
A: We ordered a custom Sinclair dual band 2 dipole array model SD312/212D-SF2P4SNM(D00). The build for that site really made it practical for a single vertical antenna to replace the dual band fiberglass stick that had suffered 15 years in the wind and ice. We also needed a broader vertical beamwidth than a higher gain fiberglass or 4 dipole array antenna would allow. With the relative closeness of our mountain location to downtown Boise, a narrow “pancake” beamwidth would literally shoot over our intended target and send most of the signal out to the horizon. Less is more in this case. The antenna is 2 VHF and 2 UHF dipoles on a common mast with 5.5 dBd of gain and 36 degrees of vertical beamwidth. This is fed with a pair of 1/2″ Eupen hardline coax runs into the shelter.
Q: What kind of antenna are you using on the Valley Ops repeater now?
A: We have special considerations at this site due to the position on a ridge line overlooking Ann Morrison Park and aesthetic requirements for our host. This replaced an aging Tram dual band fiberglass antenna that started to exhibit some snap/crackle/pop as the internals began to wander around and flex in the wind. For this site we went with the Comtelco BS450XL4.5B with 4.5 dBd of gain and a 125 MPH wind rating. It has a 30 degree vertical beamwidth which focuses more of the pattern in close to the downtown core where we need it and not at the horizon beyond where our users are.
Q: When will the Valley Ops repeater be upgraded?
A: Winter 2019 was the plan but life/work/COVID-19 lockdown slowed that way down. The antenna and feedline were upgraded by Tyler and team over the winter but the electronics still need upgraded. We are hoping to have it down during Summer 2020.
Q: What is this I hear about a West Command repeater being put on the air?
A: We are in the beginning stages of setting up a repeater in the Purple Sage region of Caldwell to restore handheld street level coverage to downtown Caldwell, Middleton and Star. This will likely be a VHF site, however, we have the equipment to make this UHF as well. After Dave Every left the area with his Middleton repeater several years ago, the town lost it’s own handheld option to support the parades during the 4th of July and Christmas seasons. Due to its position in a river valley, terrain and vertical obstructions make it difficult to have reliable coverage for handheld use during these events. Coverage mapping extends this new repeater into Nampa and Kuna. We’re excited to get it on the air in the coming months, hopefully in time for the Christmas parade if it doesn’t get shut down due to COVID-19. Anything is possible this year.
Q: How many hours did it take to build the upgrades for the North Command/North Ops repeaters?
A: Approximately 500 man hours over the course of 18 months to get the site to its current deployment.
Q: How many hours did it take to build the upgrades for the Valley Ops repeater?
A: Much less as I did a lot of the R&D during the North Command and North Ops repeater build. Probably closer to a 150 hours over 9 months.
Q: What tactical repeaters have you built?
A: I have both a VHF 2m repeater on our North Command frequency using PL 88.5 we’ve used a number of times for Willow Creek along with a suitcase LMR VHF repeater on a 151/158 MHz pair we’ve used several times. One of the things I did early on when I became trustee was apply for an LMR (IG) license with the FCC to utilize the commercial radio surplus gear we were seeing pop up on the market and having donated to the team. We currently hold an allocation for over a dozen frequencies in the low band, VHF and UHF spectrum. These are particularly useful for large events where we can provide direct communication support for the organizers rather than having to shadow all of them with an amateur operator.
Q: Why can I use LMR-400 cable at home but not at a repeater site?
A: The short answer is duplex noise. When you’re at home, the coax is only sending RF to the repeater when transmitting and receiving RF when listening the repeater. This is essentially simplex use. When used in repeater service on a mountain top, the coax is both handling the transmission and reception at the same time. LMR-400/600/etc style cable uses a tinned braid over foil shield construction – the microscopic movement of the braid against the foil as the cable ages causes microscopic arcing when the transmitter is running which shows up as snap/crackle/pop/elevated noise floor on the receiver (and hence the output retransmitted audio). Most sites ban the use of the cable; Times Fiber specifically states it’s not designed for low PIM (and they direct you to their low PIM cable as a result) and Motorola specifically called it out as an issue in their IDEN base station deployments. LMR400 good at home, bad at the repeater site. Stick to double shielded braid on braid cable like RG-214 and corrugated copper cables like Andrew (now Commscope) and Eupen hardline.
Q: Are hardline connectors really $20-30 each?
A: Yes. However a lot of them can be reused. Cut off connectors from retired cable can be found as cheap as a couple dollars each. They are usually 2-4 pieces and a set of wrenches can pull one apart.
Q: Is the $150 prep tool for 1/2″, 7/8″, 1 1/4″, etc Hardline worth it?
A: Absolutely. However… Find someone near you that has one you can borrow. Be prepared to pay full replacement cost if you break it or lose, as it the case with all expensive tools. Compared to the 9 tools required to put on a Eupen 1/2″ N connector, it’s a single prep tool and some wrenches knocking the termination time down by about 95%.
Q: Tell me more about your LMR deployment and large events.
A: I have a small cache of VHF LMR radios I use for Boy Scout events. In the past for example with Willow Creek, we would recruit 15 amateur operators to shadow the camp staff and competition stations from 7 am to 7 pm on the west face of Squaw Butte. This was difficult to say the least! Most hams will show up for a t-shirt or a burger, but Willow Creek usually provided a patch and not much more. Everything needed to survive in the desert for a day including food and water would have be provided by the amateur, including the ability to hike all over the interesting terrain. As the event evolved over the years, I began bringing LMR radios for the camp staff to lighten up the manpower requirements. About 6 years ago we started deploying a wide area private WiFi network to further move logistics traffic off voice nets and on to a digital format. With the suitcase 151/158 repeater and a dozen VHF handhelds, I’m able to fully staff the logistics needs of the camp with gear in the back of my Jeep. We’ve had great luck with the Civil Air Patrol using their cadets to handle the competition station traffic for scoring, but almost all voice comms requirements that were previously third party through a shadowing ham are now down by the scout leaders on a VHF LMR radio across the suitcase repeater. Many of the larger events off grid like the Sawtooth Relay could apply a similar method. It’s about providing the most practical way to communicate for the served agency.
Q: What radios do you run at home?
A: I have a mix of LMR and amateur gear in my shack right now:
- Connect Systems CS-800 with BFD UHF DMR
- Connect Systems CS-801 VHF DMR
- Yaesu FT-7900R
- Kenwood TK-790
- Motorola CDM1250
- Radio Shack Pro something another base scanner
- Radio Shack DX-394 Shortwave receiver – although the RFI at my house is horrible
- Motorola CDM750/CDM750 Suitcase VHF LMR repeater with ID O Matic controller and Sinclair duplexer, usually using a NMO Base Kit for the antenna
As far as handhelds…
- Motorola XTS3000 VHF P25
- Motorola XTS2500 UHF1 P25
- Motorola MTS2000 UHF1
- Motorola MT1000 UHF
- Baofeng UV-5R and UV-82 – these are my test radios for repeater coverage – if it works with these, it’ll work with most anything else
- Yaesu VX-270R
- Connect Systems CS750 UHF DMR
- 10x TYT MD380 VHF DMR in a hard case for deployments
Q: What do I need to maintain repeaters?
A: Couple basic tools to get you started:
- VOM, I use Fluke, but also carry an analog Simpson for older gear that needs a true AC VOM
- Power Meter, I like Telewave and Bird for measuring forward and reflected RF power
- Dummy Load, 125 watt
- Service Monitor – look at the cellular market as most functions of the IDEN and CDMA test sets will work for basic functions like SINAD/SA/duplexer tuning
One thing I will warn is that the NanoVNA and its variants that are under $100 right now are not suitable for tuning duplexers. A duplexer needs greater than 110 dB of dynamic range to see the peaks and valleys for tuning – these pocket VNAs struggle to have enough power/low enough noise floor to get more than about 60 dB. When a typical 2m repeater needs over 90 dB of isolation from transmitter to receiver, it’s just now enough.
Q: How long do you plan on working in repeaters and infrastructure in general?
A: I don’t know the answer to that at this point. My day job in infrastructure and it’s still exciting and interesting every day I get up. I’m one of those odd amateur operators that really doesn’t talk on the radio that much. I prefer to maintain repeaters and gear behind the scenes rather than rag chew. Nothing wrong with rag chewing, just not my thing. Perhaps being very socially awkward is part of that 🙂 One thing I do make a point of is trying to share everything I learn with those around me. I think as an expert of a certain skill, you have two core responsibilities – share the knowledge with everyone that will listen and to be constantly looking to train your replacement. It’s a driving mantra in Scouting and something I try to carry elsewhere in life.
Q: Where can I learn more about LMR/Repeaters/Antennas/Life?
A: Take a look at Repeater Builder first… Start in the Antenna Systems sections first. You’ll find probably a month worth of articles. You can spend a hundred grand on top of the line repeater hardware in the building, but if your antenna is sub par, none of it will matter.
Q: Can I place my repeater at your site?
A: Typically the answer is no. Collocation requires additional filtering, tower space, lease agreements, etc. Interference has been mitigated with the current hardware we have in place and the other collocation customers – this has been very expensive and adding additional in band transmitters can throw this out of balance. This could potentially jeopardize all current and future amateur access to the sites.
Q: Should I get surplus LMR gear or buy a new ham radio? I’m just start out.
A: Yes and Yes. I carry cheap ham radios like the Baofengs will me because they’re cheap. If I lose it or break it, not the end of the world. I also carry older surplus LMR gear because I know the RF specs are about the best I’m going to find, especially when it comes to adjacent channel rejection aka intermod. Any ham can tell you where the pager transmitters are at as they blast through on their amateur radios – my LMR gear doesn’t squawk at all at the same locations. I still carry both, if I need something random I’ll enter it in the VFO on my ham radio; however; I have almost every other frequency programmed in my LMR gear. FPP is nice but really the $30 UV5R in the glove box is cheaper than finding an FPP LMR radio in a lot of cases.
Q: How can I help?
Q: I have so many more questions to ask!
Q: Can we link to your repeater?
Q: I have an idea I want to run past you!
A: Email is usually best to get in the loop for repeater maintenance. AJ dot Grantham at gmail dot com. I also use Facebook messenger, find me @k6lor.