From: "Rein A. Smit" 
Subject: Re: [drakelist] Expensive R-4C


"Rein A. Smit"  made an utterence to
the drakelist gang
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Hi Ron,

  There are many texts on the internet about roofing filters, mixers,
high and low level ones, active and passive, high first IF vs low first 
IF etc., NF vs overload problems and pay-offs and so on.

    Here is a link, that I just ran into by:

   http://www2.arrl.org/tis/info/pdf/020708qex035.pdf

I ma not sure whether ARRL membership is required for this paper?

In relation to the R4C, you might search on Google for "W8JI" and again
you will find lots of papers, notes, remarks.

Also Bob Sherwood has published a number of papers over the years on
the R4C and its RF path.

QEX magazine is also an excellent source for this subject, in general
"modern receiver design"

Also the old hamradio magazine publish quite a few articles, look for
"Ulrich Rohde" There is an excellent book from the ARRL

  "Experimental methods in RF design"  and also an older
  "Solid State design" See also articles and design by KK7B

I hope this helps

73 Rein W6/PA0ZN




Ron Wagner wrote:

> 
> Ron Wagner  made an utterence to the drakelist gang
> ----------------------------------------------------------------------
> This discussion makes me wonder.  How "bad" is the R4B and
TR7 vs say a 
> modified up R4C?  I know that I have read about the R4C and the close-in 
> <5Kc signals with out a roofing filter.  What about the other two?  Is 
> there some teaching reading on the web?  Does the passive up conversion 
> on the TR7 avoid issues?  I would think that distortion and mixing would 
> be a problem any time you do not have a filter to cut the signals before 
> you hit an amplifier and or mixer.
> 
> I have been hamming for over 25 years, and honestly do not understand 
> all the numbers, but would like a better understanding.
> 
>>> Agreed. Without getting into too much technical speak, the R-4C lends 
>>> itself to becoming a top-notch "competition grade"
receiver. With the 
>>> proper roofing filter and the mixer mods, etc., this rig will hear 
>>> stuff that many modern rigs won't. The dynamic range is even up there 
>>> with the Yaesu FT-1000 series.
> 
> 
> And speaking of R4B mods, how good of an idea is the crystal filter mod? 
> The one where you sacrifice a T4XB for a IF can and xtal filters.  Is it 
> worth getting a basket case T4XB to perform the addition?  Was thinking 
> Al Parker has spoken of this mod before.  I have a copy of the doc, but 
> have never gone any further.
> 
>> I think I will invest the money instead in TLC for my B line - any
> 
> 
> 73,
> Ron
> ----------------------------------------------------------------------
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On Behalf of "Rein A. Smit" 
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