Batboard

RFdude

I've been thinking about helping out the local hams to piece together a simulcast repeater. We have some Glenayre VHF and UHF high stab exciters and also audio delay lines made by Allen Avionics http://www.allenavionics.com/GPDL/RP.htm The RP1105 was used for digital paging and can delay up to 1105 ...

RFdude

Have a look at this:

http://www.harrisstratex.com/products/a ... nt/tr5000/

We have lots of these! You can put in combo cards with DS1 or Ethernet interfaces. Good SNMP and web management, as well as traditional contact closures. It has proven reliable.

Good Luck!

RFdude

This will save you a lot of searching.... searched high and low on this. I use these with the NetGuardian and Optimatele RIO. Having these makes for relaxed nerves in a lengthy wide area outage. You might be very confident there is lots of fuel (like 6 days left), but the executive and PS command wi...

RFdude

SNMP is UDP. If an SNMP v1 trap is lost in transit, you will not know it. So SNMP v2 came up with INFORM which requires the NMS to echo the trap back to the originating agent to serve as an ACK. Castlerock SNMPc is excellent value for the money. HP OpenView costs an order of magnitude more. However,...

RFdude

I've designed or worked with numerous site alarm system for our networks, some using proprietary telemetry back to a server (Larse, Nortel, and some other systems) and SNMP (NetGuardian from DPS Telecom and NetPro TLAN from Optimatele.com). The mentality for the last few years has been to follow ind...

RFdude

Thanks for the warning about Duracomm PS. I'll avoid them. Be glad that the voltage sags under your particular RF influence! The other common RF caused malfuntion with switching power supplies is that the the switcher partially or fully conducts. If you are lucky, the switcher over voltage protectio...

RFdude

Do you own a mobile generator or are making arrangements with a rental fleet for urgent access? The concept of a particular connector or size of mating cam-locks works only if you have control over both the buildings and mobile generators coordinated with the same connectors. The series 22 cam-locks...

RFdude

I think you have to forgive Jim... he meant well, and I have to admit that Jim was not alone in his interpretation. You could have stated "10 kW UPS", and it would have totally changed the picture we all paint in our mind and interpretation of your situation. You cannot control the respons...

RFdude

1) Heat, duty cycle and thermal inertia. Doubling the power through the device might be OK for a very short duty cycle. The heating effects are averaged over time. Heat will melt certain components, and can cause rapid oxidation in others. Power has to flow long enough to heat things up... followed ...

RFdude

We are running a number of Smartzone systems with additional simplex channels back through the E+M channels. Two of the Smartzone systems hav -48V power supplies in the Zhone channel banks while two of the zones have +24V power supply cards. No issues. I recall that going +24V did have a limitation ...

RFdude

You are stating that your area is using the lower portion of the UHF TV band for LMR and that there is plenty of MHz between the two systems. It shouldn't cost any premium depending on how the systems are presently configured. Both systems would have to use standard multicouplers (like Sinclair 3037...

RFdude

See http://www.tccomm.com/ for a variety of media converters.

RF Dude

RFdude

There is information missing from the original poster. There are many ways to deal with this. Wavetar pointed out analog based transport. But in my circles, there isn't anything transport related that is still analog. And how to do this over the T1, ooops... DS1 link if it is digital? Someone else m...

RFdude

The MTR2000 and Quantars I've seen seem to be shipped with a little card from Motorola. They have screw terminals and 3 little white gas discharge tubes. The 4-wire circuit is wired through this on its way to the radio. A large ground lug on the above card must be connected to a good ground to be ef...

RFdude

I don't think enough info was provided to determine if lightning hit the tower or came in through the copper tether (4-wire circuit). The results would be the same to the 4-wire card if it was coming or going. What to look for is other signs and damage that might suggest one or the other. If that is...

RFdude

I'm guessing that the generator is many times the size of your Quantar load in which case the inrush current should not enter into the equation for alternator sizing. Usually when we deal with generator sizing at telecom sites, we are concerned about the worst case load: Battery charging, tower ligh...

RFdude

It is a significantly cheaper way to do things than traditional DC boards from the telecom power vendors (Argus, Marconi, Peco2, etc). There are no alarm contacts like you would get from the typical Airpax or Heinemmann AM style CB. But for the home application it isn't needed. BTW, for those intere...

RFdude

Seems a shame that you have all this 12V equipment but cannot explore the same for the preamp. As you have pointed out, the RX preamp is a critical component without which you are deaf. For this reason, I'd put its source of power as close as possible to the battery without introducing additional fa...

RFdude

In a nutshell, the 1/4 wave spacing (dipole to mast) produces the near circular offset pattern with the least amount of gain in the direction of the mast. It really isn't a null as one would expect from a directional antenna. The front to back ratio if you could call it that is 2 to 7 db depending o...

RFdude

After you have considered the other posts, especially the previous poster regarding your station parameters...Consider... TITO = Talk In Talk Out balance. You only require 50W base station TX power to be heard by a 50W mobile in the same quality that the base station hears the mobile. VHF in urban a...

RFdude

You will notice from the TXRX antenna someone else posted that for true omni, there is double the number of dipoles. Sinclair makes a SRL-335 and SRL-335-2 that has been in service many years. However, my preference for simplicity is to stick to the "offset" or "bi-directional" p...

RFdude

Thanks HumHead for your thoughts. Your point (3) regarding the AC fail beeps were overlooked... so you have alreay saved me some trouble by bringing this up. BTW... I did have an interesting issue with the DC ONLY version of the MTR2k power supply... Seems that when using these PS with large +24V po...

RFdude

Anyone know if there are any issues with feeding the MTR2000 AC/DC power supply with DC from a large, central +24V power plant? AC would not be used (ever). Battery charging would be through +24V rectifiers, not the MTR power supply which puts out over 28V. There is a +24V DC only supply available f...

RFdude

The MCX1000 can have ALL 128 channels in ONE scan list. Newer radios seem to limit the scan lists (zones) into groups of 16 channels or so. Nice when you taking long drives down the highway to new places. FAST PLL board makes scanning all 128 channels very quick (can't remember the exact cycle time,...

RFdude

For operation on 24V DC only from a large DC power plant, what would be the differences between the MTR2000 AC/DC power supply (DC only, cover the AC) versus the DC only power supply? This is more a stock/logistics issue for me. That is, stock the AC/DC version or separate DC power supply as well. I...

RFdude

It is very generic and easy to say replace it every couple of years. But in today's cash strapped reality, it may not be fiscally responsible. I'd rather apply that $8000 per year towards justification for a handheld sweep analyzer. You must already sweep all your antenna's every year during PM, so ...

RFdude

450 MHz is probably the best band to be in for close city work. Nice compromise of antenna gain and building penetration. By the numbers, if you are able to direct your 10 dB of gain exactly where you want it, you will have... well... 10 dB of gain over a unity antenna. And you can't do any better. ...

RFdude

Having been in the frequency coordination business, seeing the application described is not that unusual. Some folks overdo their coverage. For 2 miles of range, a loaded wet noodle antenna will work well (okay, this is an oversimplification, but you get the point). The path loss is a more significa...

RFdude

Capex versus Opex, that is the question. Pay capital money now to buy a system like the Daniels that will go down into deep freeze and still work, and enjoy low opex costs later. Or choose the cheap radio with some sort of heater, or other consideration to keep it warm, and you may have reliability ...

RFdude

See http://www.seabox.com for some ideas. There are also different heights. The standard box is only 8'6" which seems too low to have an overhead tray over a 7' rack. 9'6" is the next standard height. You can go to 11'6" if you use a double low trailer to maintain bridge and wire clea...

RFdude

The question is so open ended.... For connectivity, do you have Ethernet, or some form of IP, T1, or will you want dial up? Will it call into a Network Management system or simple pager. Do you want only alarms, or do you want it to control your HVAC, or have some logic in it to take action? Go to h...

RFdude

If it is a higher end transfer switch, you might want to turn on the SYNCHRONIZE feature that makes sure the E and N sources are in sync before transfering. I've had this trouble with some Motorola equipment blowing fuses if the ATS doesn't sync up. For instance, no synchronization could mean you le...

RFdude

DIN is used a lot in Europe and in North America for PCS freqs (1800 MHz). The connectors are expensive. N connectors are fine for VHF. What is this about a shelf life for Polyphasors? What is it in there that goes stale? Or were you meaning "hit" life? From taking a few apart, there is a ...

RFdude

The best desciption I've come up with for self induced (multicoupler issues) desense is a "hoarking" sound thru a tube... the kind of sound that you would make when mustering some mucus from deep within your throat.... sorry... a bit more graphic than you want... but it is exactly that sou...

RFdude

This is an awesome article with excellent documentation. Thank you for your contribution. The sad thing with equipment evolution is there are many 800 and 900 MHz transmitters being scrapped with too few people around who know how to modify for ham purposes, or in some cases, they can't be modified ...

RFdude

Alpha Technologies has lots of pole mount boxes. They likely supply them to your local cable company. http://www.alpha.com/catalog/catalog.asp?catid=3&JumpID=875&lc=1 Most are sized for some sort of battery. The larger versions have a rack portion at the top and battery below. Code approved ...

RFdude

FE-13... I looked it up in the Dupont web page. See http://www.dupont.com/fire/properties/index.html . FE-13 has an atmosheric lifetime of 264 years and the largest Global Warning contribution of all the listed agents. Check out NOVEC from 3M. It has ZERO ozone depletion, and lasts only a few days i...

RFdude

Using SI measurements, the normal float temperature for a VRLA battery is 25C. Every 10C above 25C will result in a 50% reduction in battery life. That is assuming that a temperature compensated float is used. If not, I've seen brand new batteries crack and die in a year at 35C. The battery capacity...

RFdude

To answer the original question, it depends what your operating setpoints are, and if you are using any "occupied" and "unoccupied" modes that would change the room temperature. You must consider the normal swings between the two. Assuming your heat and A/C are sized appropriatel...

RFdude

The awesome power of nature.

Other than being too busy with restoration work, I've wondered why there haven't been more posts to the batboard about telecom tower damage and related stories from Katrina?

RF Dude

RFdude

Thats like asking: "I want to buy a car. What model should it be?" Can you be more specific what you have in mind? 24 to 48 pairs of E+M that you must somehow convert and transport using a channel bank? Data? Voice? Order Wire? Ethernet? DS1? DS3? OC3? Redundant lasers? Single mode or mult...

RFdude

I'm looking for a telecom shelter electronic access system for about 1000 sites. Most popular in the industry seem to be the GE Security TRACess / SUPRA system. Comments on this system or any other solution are most welcome. With IP connectivity being more and more universal, I'm wondering if a real...

RFdude

And how many large customers in North America wanted to see TETRA come ashore? Some of these large customers even went to Europe to Radio Comm shows to look into it. As soon as exhibitors found out they were from America, the stonewalling started. As if a gun was placed to the exhibitors head. Don't...

RFdude

ASTROMODAT wrote: "I've had great help with GCI's, albeit I think I also helped Motorola as they found a lot of issues with their firmware and CPS via this process, so we both won." :evil: And then they keep the bug to themselves and don't tell others about it. So every Motorola customer t...

RFdude

Thats what I suspected! I heard they have a new revision available in the last couple of months. We are experiencing difficulties with failed and microphonic LO's. The number of failures is unusually high. Like some other companies, some of which begin with the letter M, Alcatel isn't revealing much...

RFdude

Yes, you can use almost anything with high gain antennas. See http://www.hyperlinktech.com for lots of ideas and hardware. Another inexpensive antenna vendor is http://www.superpass.com. A 15 dBi gain antenna at both ends, and placing the transmitter right behind the antenna will work (short feedlin...

RFdude

Just wondering if anyone out there has experienced issues with MDR-8000 Local Oscillators or if you are experiencing any other reliability issues with this series of radio?

Thanks!

RFDude

RFdude

Thanks. I'll have a close look at them. Been buying Zenith Controls (GE) which are very small at only 18"W x 24"H x 10" for the standard 200A. Also KOHLER KDT which is marginally bigger, but has a better price point. Kohler also has neat engine controls that will now talk to the Monit...

RFdude

Jim is correct in his assumptions. That is basically what is being done. For CAPEX and accounting reasons, no company likes to own part of an asset. So usually there is some "one-for-one" going on in the background with sharing multiple sites. The generator owner will wire all the alarms a...

RFdude

Over the last month, I've just gone through all these variations with a fine tooth comb to confirm what we already know. Think of two competing telecom providers sharing the same tower, and utility transformer. Each has their own electrical service and meter. Now they want to build and share ONE gen...

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