Transverters

[Kevin Murphy]

Hi,
I notice a trend with the Elecraft transverters, in that there is a
second RF device, such as a ERA or MAV MMIC following the 1st RF RX device.

With most other designs I have seen, there is a filter between the 1st
and second RF amplifier stages to limit out of band signals being
amplified by the second RF stage.

In rural areas there is a lesser need for out of band  filtering, but in
  suburbia there are many out of band signals.

Comments please?

Kevin
ZL1UJG

PS I don't own  a Elecraft XV series transverter.

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[Robert Friess]

Hi Kevin,

I designed the XV transverters for Elecraft and will attempt to answer your
question.

Receiver design always requires some compromise between sensitivity and
dynamic range.  To maximize sensitivity, lossy elements, like filters, are
moved farther away from the antenna to minimize their effect on noise
figure.  Sufficient gain is also provided to minimize the effect of the
noise figure of the following stages of the receiver which in this case is
the transceiver used with the transverter.  To maximize dynamic range, the
receiver designer would do just the opposite.  Selectivity would be placed
as close to the receiver input as possible and gain would be minimized.

The XV transverters in standard configuraton attempt to balance these
requirements in a way that is optimum for most users.  We do recognize that
there are situations such as very high interference environments or when
external preamps are used, or when a very low noise figure IF transceiver is
used,
where the standard configuration is no longer
optimum.  It is for this reason that the manual includes instructions to
remove the ERA amplifier from the signal path to reduce the gain of the
receiver ahead of the narrowband filters.

73,
Bob, N6CM


----- Original Message -----
From: "Kevin Murphy" <[hidden email]>
To: <[hidden email]>
Sent: Wednesday, April 05, 2006 12:34 AM
Subject: [Elecraft] Transverters

> Hi,
> I notice a trend with the Elecraft transverters, in that there is a second
> RF device, such as a ERA or MAV MMIC following the 1st RF RX device.
>
> With most other designs I have seen, there is a filter between the 1st and
> second RF amplifier stages to limit out of band signals being amplified by
> the second RF stage.
>
> In rural areas there is a lesser need for out of band  filtering, but in
> suburbia there are many out of band signals.
>
> Comments please?
>
> Kevin
> ZL1UJG
>
> PS I don't own  a Elecraft XV series transverter.
>
> _______________________________________________
> Elecraft mailing list
> Post to: [hidden email]
> You must be a subscriber to post to the list.
> Subscriber Info (Addr. Change, sub, unsub etc.):
> http://mailman.qth.net/mailman/listinfo/elecraft
> Help: http://mailman.qth.net/subscribers.htm
> Elecraft web page: http://www.elecraft.com
>

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