[ARC5] Visual alignment of BC-454

[mstangelo at comcast.net]

Jay,

Could they have been EXAR function generators? Unlike Signetics and National they're still in business:

<http://www.exar.com/communications/timing/voltage-controlled-oscillator-vco/xr2209>

Mike N2MS
----- Original Message -----
From: Jay Coward <jcoward5452 at aol.com>
To: kgordon2006 at frontier.com, dennis monticelli <dennis.monticelli at gmail.com>
Cc: Arc5 at mailman.qth.net
Sent: Thu, 23 May 2013 23:20:05 -0000 (UTC)
Subject: Re: [ARC5] Visual alignment of BC-454


There were some function generator chips back in the eight's I used for ramp and pulse generation Can't remember the manufactuer but may have been Signetics and National semi. I would use these to make a voltage ramp for an analog voltage to current driver for YIG microwave oscillators to make "cheap" swept signal sources for production line use at Avantek, I would  set up a 0-10V ramp with a very short fall time. the simultanious pulse out was available and the short downward pulse I would offset to give a negative -3V pulse which I fed to the scope's Z input and that would blank the scope's retrace.
 These chips are pretty handy and one could easily breadboard into a handy bit of test gear.
 My $.02, YMMV. etc.
 Jay KE6PPF


-----Original Message-----
From: Kenneth G. Gordon <kgordon2006 at frontier.com>
To: Dennis Monticelli <dennis.monticelli at gmail.com>
Cc: Arc5 <Arc5 at mailman.qth.net>
Sent: Thu, May 23, 2013 12:51 pm
Subject: Re: [ARC5] Visual alignment of BC-454


On 23 May 2013 at 9:36, Dennis Monticelli wrote:

> Ken,
> 
> To be more clear:  The asymmetry to which I was referring was the the
> freqeuency hump in the passband, not the asymmetry of the retrace.

Yes. I figured that out, thanks.
 
> Ian is right in stating that the retrace should look like a mirror
> image of the forward trace.  Something is going non-linear during the
> retrace.  I think that is a separate issue from the passband hump.

Well, IMHO, IFF the sweep is REALLY a ramp or true sawtooth, rather than 
a triangle, the retrace should show essentially a very weak straight line.

A triangle wave or a sine wave would show two traces, one the mirror-image 
of the other.

My sweep output is almost a ramp. The return-to-zero end is NOT a vertical 
line. It a quite finite, and then some, return to zero. 

And the ramp itself is not straight either. In fact, the slower the sweeps, the 
more curved the ramp actually is. 

As I said, in order to get what is really there, I need a much better 
ramp-generator...one with almost instant return-to-zero, and with a truly 
linear ramp.

I am investigating various circuit diagrams.

Ken W7EKB