[Icom] Re: Icom digest, IC-746PRO issues

[Guillermo]

Hello all:

Roy Sakabu escribi�:
> 
> I have a very quiet Icom 745 that I would be happy to trade with you Ken.
> Just kidding (not about the quietness though).  I agree that the older rigs
> tend to sound more quiet while not being any less sensitive.  I started with
> an R-75 and 746 and have since picked up a Kenwood TS-940SAT and IC-745 and
> think that they tend to be less noisy than the latest rigs.  It may be that
> the added sensitivity is just picking up more atmospheric noise which was
> always there and the older rigs were just "insensitive" enough to miss it.

	I don't think that today's rigs are more sensitive than older ones.
What I think is that later rigs are populated with digital stuff, and
digital changes of state (without mentioning the phase noise added by
the several VCO with their associated PLL circuits inside) make them
noisier. This noise travels through supply lines everywhere. And if you
see inside the rigs, they are more and more built like car stereos, with
less shields.
I have a friend's IC 746 by the moment, and to keep its reception
similar to that in my TS440 I have to use ANR at 9 o'clock. This 746 is
more noisy.
And not to mention comparing against FT101's, TS520, 820, and so..

Just my experience.

> The DSP noise reduction helps a little, reducing the RF gain also helps.  Do
> you know about the old timer's trick about turning the RF gain all the way
> down, the AF gain all the way up and adjusting the output to the speaker via
> the RF gain?  It works pretty good so long as there is a decent S/N ratio.

You must turn off AGC also. And many times, adding the attenuator helps
a lot (if you have enough signal input).

Best regards
Guillermo - LU8EYW.