On 4/30/2012 2:01 AM, Charles Harpole wrote:
>
> I think we should also count pieces of incoming db lost by insertion of
> various devices.
>
>
>
> I know ever coax joint, every coax switch, and so on costs rcv db.
These are miniscule. The loss figures are for the maximum frequency.
Even on 144 and 440 I may have as many as a dozen connectors from the
exciter, amp, top and bottom of the tower, power dividers and the
pigtail to the actual antenna. They typically add up to less than a db
loss even at 440.
At HF they are generally of a magnitude that can be ignored *if they are
well designed and constructed* connectors.
>
>
>
> But what does an amp in line take away? Tubes or SState better or worse?
As they use a bypass line and two relays, it depends on the construction
of the individual amp. On average I doubt there is even a tenth of a db
difference between quality, well designed amps be they SS or tube. OTOH
the difference between well designed amps using quality components and
*economy* amps it may be quite a bit.
I've not picked any figures because there are so many variables. At HF
you can *usually* get away with far less expensive components (Open
frame relays) with out noticeably increasing loss.
>
>
>
> Does an antenna tuner take away any parts of rcv db?
Probably the tuner takes out more signal than all the connectors
combined. IIRC this discussion was held a while back on TowerTalk so it
should be in the archives. I don't remember which manufacturer it was,
but they listed insertion loss for their tuners. I'll try to remember
to check my manuals.
73
Roger (K8RI)
> Inquiring minds want to know. thanks, 73
>
>
> Charles Harpole
> k4vud@hotmail.com
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