[Ares-races] Re: Use of HF for local communications

[Steve Uhrig]

Once upon a midnight dreary, Joe pondered, weak and weary:

Hi Joe,

> There is a group that is trying to promote the use of HF in the State
> of Connecticut for emergency communications WITHIN the state.  For
> those of you who are not familiar with my state, it is approximately
> 100 miles East to West, and 50 mile North to South.  The primary
> frequency for communications has been selected as the 75 meter SSB
> band.  I myself do not see the logic in this.

Some use 10 meters which has reasonable ground wave coverage and 
smaller antennas.

Maryland has had MEPN (Maryland Emergency Phone Net) on 3920 
megacycles (1800L Maryland time 7 days a week) for decades. I use QRP 
SSB with a homebuilt Elecraft K2, and with my 5 watts I'm heard 
statewide. It is to my benefit other net members are well trained and 
can work with weak signals. Sometimes I'm only S9 ...

> I am in favor of the use of 2 meter repeaters to cover this area, being
> careful to select repeaters that are centralized to the area and that
> have backup power sources. My opinion is the HF would only be effective
> for communications from Connecticut to other areas OUTSIDE the state.
> HF would only be my choice if the 2 meter network failed to give
> adequate coverage in isolated areas. 

I agree with your logic in general.

Perhaps try to get to the people in CT and ask them exactly what 
prompted their decision to use 75 meters. Absent their info, we only 
can speculate.

I don't know the geography in CT. Maybe there are a lot of hills, 
ridges, etc. which makes it difficult to get out of major areas on 2 
meters. The Baltimore area has the famous 'Pikesville Ridge' which 
largely isolates the western suburbs from VHF, so repeaters have had 
to go to multiple receive sites and voters to cross the ridge, which 
are expensive, finicky and require a lot more backup power 
infrastructure as well as a UHF pair for each remote receiver. 

Sustained backup power for days or longer without commercial power 
requires a store of fuel which is not practical in many repeater 
installations. If you've got a machine in the top of an elevator 
shaft of a zillion story hotel, how are you going to support a 
generator and a few hundred gallons of diesel? May not be affordable 
even if it can be done, you have fire codes and all sorts of nonsense 
to deal with at a governmental and facility level.

You can't get the hose from a tank truck up to the roof, and it's no 
fun filling a 275 gallon diesel tank with 5 gallon cans hauled up two 
at a time. Ask me how I know!

You don't have any of this using HF.

There may be factors other than technical. Politics has forced a lot 
of decisions to be made which were not the best technical solution 
but were the only options politically.

And, in general, the simpler the infrastructure the more reliable it 
tends to be. Repeaters need skilled regular maintenance frequently 
using test equipment beyond that available to most amateurs. 
Repeaters tend to be located in high places which may attract 
lightning and few amateur repeaters can afford to spend the money to 
harden their systems properly. In an emergency you may not be able to 
get to the repeater physically to make the simplest of repairs or 
configuration changes.

Debates could support both sides, but it's academic without knowing 
all aspects relating to the decision to use 75 meters. There's 
certainly pros and cons to either.

> What have been your experiences?

Above.

Don't underestimate HF groundwave. The military uses it a lot. 

Good discussion. If you learn anything from the persons who made the 
decision to go with HF, please share them. We all could learn.

Steve WA3SWS


*******************************************************************
Steve Uhrig, SWS Security, Maryland (USA)
Mfrs of electronic surveillance equip
mailto:Steve@swssec.com  website http://www.swssec.com
tel +1+410-879-4035, fax +1+410-836-1190
"In God we trust, all others we monitor"
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