[Hallicrafters] s-76

[Carl]

A 50 kc IF was simply the easiest way to get decent skirt selectivity in the 
days before multi pole crystal filters became affordable. In the late 40's 
and early 50's there were many CQ and QST articles using very low frequency 
outboard IF's to overcome the shortcomings of a 455 kc IF with a single 
crystal.  The WW2 BC-453 was the most popular by far. Others used TV peaking 
coils to go as low as 15-20 kc and later Miller added 50kc transformers to 
their line.

The SX-88 took 50 kc to the highest order and the SX-115 was no slouch 
either.

National used 80 kc just to be different (-;

Carl
KM1H




----- Original Message ----- 
From: "Grant Youngman" <nq5t at tx.rr.com>
To: <hallicrafters at mailman.qth.net>
Sent: Friday, March 12, 2010 11:19 AM
Subject: Re: [Hallicrafters] s-76


>>
>> However, I have had some trouble aligning the S76 ... if I remember
>> correctly the first IF is at 50kHz, much lower than the usual 455kHz.
>> I'm curious to know why this frequency was chosen?
>>
>
> The S-76 is interesting precisely because of the low frequency (50Khz) 2nd 
> IF.  This was the first Hallicrafter's in which this IF appeared and then 
> continued in most of the follow-ons -- SX-96, 100, 101, 111, 115, 117, 
> etc.  The S-76 gets mostly ignored, but it's the introduction of that IF 
> strip -- largely unchanged, although enhanced in the SX-88, as the 
> Hallicrafter's hallmark IF -- that makes it interesting, not to mention 
> the huge S-meter.
>
> Apparently there's something there in that meter,  since for many modern 
> radios one can buy a piece of software that will put an enormous meter on 
> a 60" display so you can read it from 100 yards away if you like.  Those 
> big meters impress your visitors and give you the ability to give that DX 
> it's typical S-9 signal report to a precision of several digits :-)
>
> Grant/NQ5T
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