[VHFcontesting] Re: [VHF] Cell Sites

[jeff millar]

Roger...

A neighbor (David, wb1cmg) went through this.  He had 180 ft of Rohn 45 
and the cell company wanted to get on it.  They uprated the guy anchors, 
installed new larger guys, built a road and building. They installed 
three sectors at the 120 ft level.  Dave gets the top.  My 440 repeater 
sits on that tower.  Dave is active on all VHF, UHF and microwave band 
and has not had interference, even on 900.

I know from experience that cell transmitters use bandpass duplexers 
with very high rejection of out of band signals.  I wouldn't worry about 
TX noise from the transmitter.  They're somewhere around 870-890 MHz and 
probably have a TX noise level of -40 dBm prior to the filter, then the 
filter rolls off at about 30 dB per 5 MHz.  Assuming worst case band and 
Tx carrier placement, the filter will still have about 60 dB of 
rejection by 902/903.  Then add 60 dB of antenna to antenna isolation 
and the noise floor in your 900 Rx probably runs -160 dBm.  These 
numbers are familiar to me because the company I work for designs Cell 
systems and has to deal with our potential to generate intermods and Tx 
noise in the public safety band and other frequencies.

If you want to test this, drive up close to a cell site with a yagi and 
Rx and check for a noise rise when you point at the antenna.  You won't 
see any.

Dave talked the cell company into increasing the size of the building 
and giving him the use of half...but they did use his tower. 

The going rate for this is between $1000 and $2000 per month.  Don't let 
them short you.

jeff, wa1hco

w3sz wrote:

> Hello, All,
>
> I am asking for advice from the collective wisdom of the VHF and  
> VHF-Contesting lists.
>
> I have been approached by a cellular company wanting to put up a tower 
> on  my property and of course to lease that space.
>
> My immediate response on reading the letter was, "Are you crazy?"  I 
> had  this response of course because of concerns about EMI in both 
> directions,  me to them and them to me.
>
> I am however by virtue of the fact that my property is quite high, 
> and  probably sees every cell tower for more than 10 miles in all 
> directions  already exposed to multiple cell towers, at least a couple 
> of which are  fairly close [I would guess on the order of 0.5 to 1.0 
> mile away, but that  is just a very rough guess].  I have a few bleeps 
> and bloops on 903, but  that is it in terms of problems as far as I 
> know.  I am not aware of any  desensing on the other bands {I operate 
> 50 MHz thru 24 GHz weak signal  terrestrial, and 144 MHz EME}.  I use 
> cavity filters before the preamps on  144 MHz EME, and helical filters 
> on 50 thru 903 MHz before the preamps.
>
> The amount they offer as a starting point for negotiation is not 
> large,  but it would cover my property taxes and in addition leave me 
> with more  money to spend annually on ham radio than I would 
> ordinarily allow myself  to spend.  So I am starting to consider this, 
> thinking that maybe  suffering some additional bleeps and bloops on 
> 903 would be a small price  to pay for the financial benefits of such 
> an arrangement.  My wife of  course thinks this is a good deal, and 
> has already figured out that if I  do this it will be 'x' years before 
> the rent we receive from the deal will  pay off what I have already 
> spent on ham radio-related expenses I have  incurred at the property.  
> So there are domestic advantages to the deal.   ;)
>
> Other thoughts that occur to me:
>
> 1.  No neighbor problems currently with my present towers.  This 
> could  potentially cause some I would think.  And if I don't do the 
> deal, and  make that known, it could be a positive if complaints ever 
> surfaced.
>
> 2.  If the cellular signals are strong enough, I could suffer 
> significant  problems on other bands [besides 903] due to mixing 
> products.
>
> 3.  I don't know how MUCH rent / other benefits it is reasonable to 
> ask  for.  I faintly recall a QST article where I believe the author 
> got in  addition to rent a new tower, antennas, maintanence, etc.  
> Does anyone  have knowledge of the 'going lease rates', which I am 
> sure vary a lot?  I  am in Southeastern Pennsylvania.
>
> 4.  I would need to have some agreement that the cell company would 
> need  to accept any interference that occurred from me, with the worst 
> result  allowed being that they would terminate the agreement.  No 
> other damages  allowed.  And maybe they would have to leave the tower 
> in place if they  left.
>
> Any thoughts from those who have been down this road, or considered 
> it, or  know someone who has, would be appreciated.
>
> Thanks in advance, and
>
> 73,
>
> ROger W3SZ
>
>
>