[Elecraft] KX3 vs FT817 - how do the "insidedimensions" compare?

[Paul Christensen]

> "I had the impression that the rise of the Ham-band-only transceiver in 
> the
> 1950's and 60's was based on simple economics.  It was cheaper to drop
> general coverage receive..."

Just the opposite, I think.  Some of the poorest performing -- and least 
expensive receivers provided general coverage.  The most expensive receivers 
of their respective eras were the Collins 75A, Collins 75S, Drake R-4, and 
National HRO, all of which were at the top-end of the purchasing ladder in 
their day.

I have several Hallicrafters receivers between the SX-9 and SX-100 and 
others in between.  The cheap and dirty way of providing GC was to find the 
calibrating Main tuning cap points, activate the xtal calibrate marker, then 
tune the bandspread cap to the nearest dial marker.  The problem is that 
mechanical variations in the GC main tuning greatly affect bandspread 
tuning.  For example, on my SX-100, the entire tuning mechanism functions on 
the use of a highly tensioned steel piano string.  The slightest vibration 
on the table transfers from the chassis, into the gears, the dial string, 
and ultimately, the tuning caps.  Because of tuning instability, the SX-100 
is one of the worst receivers I've owned and unfortunately, it was my first 
receiver as a novice in '72.

OTOH, Collins and Drake receivers from the '50s and '60 suffer no such 
problems.  The PTOs are temperature compensated and highly linear from 
end-to-end.  It is possible to use a PTO and a crystal heterodyne scheme at 
the first LO, but was very expensive.  The Drake SPR-4 was such a GC SWBC 
receiver that had a PTO and up to 23 pre-mixer crystals  - and it still 
didn't offer contiguous coverage to 30 MHz.

Going back even further in time, look at the National SW-3, FB-7, and HRO 
frequency-determining topology.   The SW-3 regen and HRO could certainly 
accommodate GC, but the real performance attained in the 1930s was realized 
when the bandspread clips were engaged, severely limiting tuning range to 
only the ham bands.  For a non-PTO tuning method, National's HRO gearbox, 
coil boxes with taps, and elliptical tuning dial were a flash of genius.

So, I see the early "ham bands only" receivers as the more superior, and 
expensive product.  Apart from the mentioned Hallicrafters SX receivers, I 
don't collect and restore any other type of GC receiver.  And, how anyone 
can elevate the SX-88 to "Delivered from God" status is well beyond my 
comprehension!

Paul, W9AC

----- Original Message ----- 
From: "Ron D'Eau Claire" <ron at cobi.biz>
To: <Elecraft at mailman.qth.net>
Sent: Sunday, October 23, 2011 3:12 PM
Subject: Re: [Elecraft] KX3 vs FT817 - how do the "insidedimensions" 
compare?
 It was cheaper to drop
> general coverage receive. It was also true that they were typically better
> performing than most general coverage receivers, mostly due to improved
> input filtering that protected the mixer from large off-frequency signals.
>
> As you may recall, most general coverage receivers up to that time used
> simple L/C tunable input filters that required multiple knob-twiddling or 
> a
> big "ganged" multi-section tuning cap with the stages carefully adjusted 
> so
> they "tracked" the across the tuning range.
>
> A well-designed fixed tuned input filter was better, especially important
> consdering the relatively easy-to-overload mixers in common use back then.
> That gave the ad writers a good explanation for the limited tuning ranges.
>
> Ron AC7AC
>
> -----Original Message-----
> After almost 50 years of being a ham, I see that the conventional wisdom
> of NOT including general coverage in a receiver has been refuted.  It was
> thought to be at the expense of performance on the ham bands.
>
> How have modern design techniques overcome this limitation?
>
> 73 de Jim - AD6CW
>
>
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