Low Band Question: Which split is best?

[W8UU]

I have a question for fellow radio techs with real-world experience with low band radio systems. I am wanting to establish a small simplex (base to mobile and mobile to mobile only) business band radio system for a family business. The local topography is hilly and rural. The base station would be located on top of a hill, probably on a telephone pole or small metal tower and not more than 50 or 60 feet up. There will be six or seven mobiles that will cover a 20 mile radius of the base station. The base will most likely be 100 watts and the mobiles must be limited to 50-60 watts underdash with base loaded antennas. I realize there is some compromise on the mobiles but Maratracs and "tree-banger" quarter wave antennas will not work for us in this situation.

Here's the question: We will be purchasing used radios from a local shop. All are working and in good electronic condition. Most are trade-ins from fire departments that went UHF or High Band. We have radios in the 30-36 MHz and 42-50 MHz splits available to purchase, and could probably get the 36-42 MHz if we asked, since several local law enforcement agencies vacated the 39 MHz band some time ago and that old stuff is laying around somewhere.

Is there any significant benefit in licensing a frequency, say in the 30-31 MHz business band vs. the 35 MHz business band? Or requesting something in the 43-44 MHz or 47-49 MHz upper end as opposed to the lower side of the band? I'm talking about artificial and man-made noise, coverage range, skip interference, etc. Or does it really matter? We will be licensing a new system from scratch, and would request a "sub-band" from the appropriate frequency coordinator. I'm just interested in any real world experiences anyone has had.

Thanks in advance.

Rick

[Bill_G]

This is for a plumbing company with service vehicles that will carry spare pipe on the roof? Long lengths of copper that will begin to approximate quarterwave length antennas? That band? (cough)

Is there any way you can talk them out of this decision? I realize bucks can be tight, but this idea could easily be a waste of money.

[W8UU]

Well, its not an absolutely done deal, but they don't want to rent community repeater space. Cell phone service is spotty in at least 60% of the service area. VHF High Band simplex is a possibility. Is there a huge problem with low band or is it just not a personal preference? Just curious.

[Bill_G]

I love low band. Ground wave propagation like no other band. Creeps through hills and forests pretty good. Gets put on it's butt by atmospheric, mechanical, and electronic noise. It has a high dink factor. If you can keep vehicle noise sources down, if you can properly load the xmitter and rcvr into the antenna, and if your customer goes in knowing there will be days when he can talk 300 miles, but not 3, and he is willing to take a chance on used equipment with all the joy that brings, then plug your nose and jump into the deep end of the pool. When low band works well, it rocks.

[W8UU]

I always liked low band too. At one time, everyone used it around here. Fire and EMS on 46 MHz, Sheriff and Police on 39 MHz, Park Rangers on 31 MHz, Highway Patrol on 44 MHz, Highways trucks on 47 MHz, et al. With the implementation of a statewide 800 trunked system and VHF/UHF repeaterts for local public safety forces, there is a glut of decently-maintained used (some of it lightly used) equipment on the market.

The equipment I am looking at has the extender feature, and getting a professional installation by a radio shop is a given, including any extra grounding or noise supression kits that may be needed. I realize skip interference is unpredictable and you get what you get and you really can't do anything about it.

Back to my original question ... is there any significant technical or operational difference in using 30-31, 35, 43-44, or 47-49 MHz. Since all are now available to Business Band (90.35) licenses, which is the preferred band? Or does it make a difference?

Rick

[WB6DGN]

"This is for a plumbing company with service vehicles that will carry spare pipe on the roof? Long lengths of copper that will begin to approximate quarterwave length antennas? That band? (cough)"

Not to worry! If your truck is carrying copper and it's not under lock and key, IT WON'T BE THERE LONG ENOUGH to cause much of a problem.

[WB6NVH]

I guess you haven't been around during some of the previous sunspot cycles! To answer your question, you want as high a split in the band as possible, unless your customer needs to talk to his vehicles in Guatemala. During an active sunspot cycle, 30-40 MHz is going to be like CB. This is one reason why so many users are vacating (and have vacated) that band.

However, over the past 10-12 years, or longer, the sunspot situation has been pretty lame so the potential for what can happen has only been in the memory of those of us who are getting older.

Even in an active sunspot cycle, the MUF tends to be about 42 MHz, so a 47 MHz system will experience less skip interference.

A local plumbing company used to have a 60 Watt 31 MHz simplex dispatch system with a modest antenna. I was reading a scanner guide published in Australia and there was their channel listed, with the remark "California plumbing company, usually good signals."

California Highway Patrol is expanding and upgrading its low band network this year and adding a number of mountaintop 39 MHz channels to the system, which was once almost exclusively at 42 MHz. It is also being modified to be full time split-site repeat, so you will now hear the cars as well as dispatch. Get those QSL card requests ready whenever the sunspots finally return!

[Bill_G]

Around here PTL (Peninsula Truck Lines) had a store and forward repeater system on 42M up and down I5. Hilarious and maddening to listen to.

"(sizzle)Tacoma base to 7452(sizzle) ........Tacoma base to 7452 .......(sizzle, pop)Tacoma(sizzle)base (pop) to 7452(sizzle)......(skkkkkk)coma bas(POP!)(skkkkkkkk)452 .......(skkkkkkkkk)head ........(sizzle)go ahead(sizzle).......go ahead........(sizzle)go ahead(sizzle) ......."

You get the idea.

[W8UU]

How bad are these issues if I could obtain a 48 or 49 MHz channel?

[WB6NVH]

Well...you would probably be happy with 49 MHz, and do use PL or DPL. The sunspot cycle has to be pretty decent to get skip up to 49 MHz, and so far it has been maddeningly dormant for those of us who are hams.

I suppose there might be some sporadic E traffic on 49 Mhz during the spring and early summer, but with PL on, if there was any, you woudn't notice it anyway. It tends to not last very long.

The main thing is to stay away from something like 31 or 35 MHz, although right now anything will be great for local use as the sunspots are surprisingly absent.

By the way, after the sun sets, the interference goes away, but then not every business operates at night.

[W8UU]

Thanks. That was what I suspected. I like to play around on 6 meters and I am aware of band conditions there. The VHF Low business band channels are something else, though. I'm wasn't sure where we are with so many users migrating away from 30-50 MHz. I wondered if getting a clean low band channel, especially with our hilly topography, might be the best bang for the buck. The business is a rural transportation company, doing everything from taxicab rides to contract work for the VA and the senior citizens agencies. As you might suspect, they are occasionally called to the backside of nowhere and often need address verification or, in the case of doctor's appointments, the client needs to be transported by paramedics once the driver arrives and finds out the situation is more serious than originally known.

I'll nose around and see about the cost of high band radios. They might be within a few hundred dollars to go VHF when everything is figured up. Not sure about the availability of high band channels. Last time I checked the FCC database, there was still a lot of activity there. I know we'd have to get narrowband equipment, since tapping in to the flood of 25 kHz bandwidth used radios is just throwing money away.

Again, I appreciate all the help.

Rick, W8UU

[Bill_G]

VHF is a better choice. There is more product available. The antennas are easier to maintain, and more efficient. If they do elect to install a repeater, the duplexer will be smaller and easier to install. Higher gain antennas are available in VHF for the base and the trucks. There is plenty of man-made noise in VHF, and plenty of it made by vehicular sources. But, it's generally easier to resolve. It still has a good ground wave with a very strong sky wave component. Green leaf attenuation is higher, but it will still creep over rolling hills and through winding valleys well if the base station HAAT is good and the base antenna is above the canopy. Coverage is more predictable and reliable in VHF than low band. Those are just a few reasons to go high band over low band.

[KitN1MCC]

the higher frequency is good. but there are a lot of 36-42 radio just looking for a home very cheap

[W8UU]

the higher frequency is good. but there are a lot of 36-42 radio just looking for a home very cheap

Agreed, especially on eBay. That's the only split that cannot easily be used for ham radio purposes. The biggest problem is that 36-42 is primarily a military sub-band with government/police operations at 37 and 39 MHz. Business users would need to get one of the handful of 37 MHz power/petroleum channels from a designated frequency coordinator to qualify for an FCC license.

Rick