[GreenKeys] ARRL Handbook TU Limiter Circuit wanted

[Ralph Mowery]

I am not sure when the 709 came out, but it was about the same as the741 op amp.  

I built a ST-6 in the early 1980's on a piece of perf board.  That thing still used about 7 of the op amps and a few transistors.  While not extremely difficult to build, changeling enough for just a ham hobbyist.   That unit is probably about all the common ham would build.  I was lucky as I had a Heathkit frequency counter and could adjust the filters to the exact frequency.  Hal did come out with the unit in several forms from kits to maybe a wired unit.

Ralph ku4pt


-----Original Message-----
From: Bob kb8tq [mailto:kb8tq at n1k.org] 
Sent: Wednesday, January 20, 2021 6:05 PM
To: Ralph Mowery
Cc: greenkeys at mailman.qth.net
Subject: Re: [GreenKeys] ARRL Handbook TU Limiter Circuit wanted

Hi

The 741 op amp came out in 1963. Poly Packs had parts “for cheap” not more
than a couple years after that. Once you had cheap / simple op amps ….. this 
all changed in a big hurry. 

Bob 

> On Jan 20, 2021, at 5:54 PM, Ralph Mowery <rmowery42 at charter.net> wrote:
> 
> It has been a long time ago that I read the articles by Hoff.  I think that
> he decided way back that the limiter was not the way to go IF you had other
> circuits that were automatic threshold/decision correction and some other
> circuits.  However for the hams and ones with limited abilities or budgets
> then the limiter circuits were the way to go.   His designs of the later
> tube circuits and the ST-6 were the standards to shoot for back then.
> Simple and inexpensive enough to build but worked very well.  One good thing
> about the limiter/discriminator circuit is that the tones do not have to be
> spaced apart and on frequency as close.  Way back then very few had a good
> way to build and calibrate filters and tone generators for 170 Hz shift.
> Now an audio frequency to high RF frequency counter is a few bucks and
> computer software can generate and detect audio frequencies for free.
> 
> Ralph ku4pt
> 
> 
> 
>