[TowerTalk] $/db

[k6ll@juno.com]

On Thu, 19 Aug 1999 17:46:10 +0000 alsopb <alsopb@gloryroad.net> writes:
>
>Guys,
>
>It looks like many stations are pushing the
>envelop on improvements that can be made to
>achieve a better transimitted signal.  I'd like to
>try and quantify what that "extra 2 db" might
>cost.

Don't forget to double the benefit if any change helps also
on RECEIVE. Multiply the benefit by X if the change helps
on X number of bands.

>
>I'd like to hear what station improvements you
>would make to pick up extra db's.  The goal is to
>identify the most cost-effective ones.
>It is clear that this is probably band dependent. 
>It surely is station dependent.
>
>Assume that you can run no more power.  All "gain"
>has to come from the output of the amp to the
>ether.  Assume only the HF bands and you're
>primarily a DXer.  
>
>Examples might be:
>
>1. Increase the number of radials on my 160 meter
>inverted L from 8 to 60.  Gain estimate 2 db (via
>less ground loss), cost = $1000  cost/db =$500

Transmit benefit only. Rx is atmospheric noise limited.

>
>2. Replace my 10 meter antenna RG8 feedline (300')
>with LMR600 .  Cost = $300, gain =2 db, cost/db =
>$150.

I think it's more like 2.4 db. Under certain conditions on
10 meters, this gain may help on receive also, so multiply
the benefit by 1.5.
300/(2.4 x 1.5) = $83/db

>
>3.  Raise my 40 meter dipole from 40 to 70'. 
>Estimated gain at 25 degree radiation angle = 3db,
>cost =$100 (tree climber), cost/db = $33.

This would help on Rx also, so divide by 2 = $17/dB
>
>4. Match antennas better and get rid of antenna
>tuner.  Cost = 0, gain = 1db.

Tx benefit only.
>
>Please give the old configuration and the proposed
>improved configuration.

You really need to start with a particular specific configuration,
and figure the benefits incrementally from that point. However,
I think the concept of multiplying the benefit by 2 if it helps
both receive and transmit, and multiplying by X if it benefits
X number of bands, is quite helpful. It is to me, anyway.

Dave Hachadorian, K6LL
San Diego, CA
K6LL@juno.com





















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