On Thu, 6 Dec 2012 00:45:17 -0800 (PST), Dana wrote:

On Tuesday, December 4, 2012 6:54:15 PM UTC-8, Arid ace wrote:

My error - the IC mentioned should be SL612C and nowadays it's available from

China via eBay:

http://www.ebay.com/itm/120922014405... 4.m1497.l2649

It has a much wider AGC range than the TL026, up to 70 dB IOW higher than the

stage gain.

Let's see. SL612, $8+ each. TL026 $1.50 each.
-3dB bandwidth - SL612 up to maybe 15MHz. TL026 up to 50MHz.
SL612 AGC range 70dB, gain of 34dB. TL026 AGC range 50dB, gain of 38dB.
SL612 obsolete. TL026 in production.

An AGC range far in excess of stage gain isn't much use if the stage
is overloading anyway.

Why again would I consider the SL612? :-)

Dana K6JQ

The data sheet of the TL026 doesn't mention the maximum input signal that can be
processed. For the SL612 that is 250 mV rms. Then there's the supply current:
less than 5 mA for the SL612 but for the TL026 it's 6 times as much. Not to
mention the issue of stability.

For an IF higher than 10 MHz, the SL611 has -3 dB at 80 MHz and for the SL610
that is 120 MHz. On SW, an IF amp with low NF allows for a passive mixer as
long as the overall NF stays below ~10 dB. The SL612 has a 3 dB NF and a passive
mixer like the VAY1 a loss of ~ 5.5 dB so even with some input filter losses,
one can design a radio with high dynamic range, low power consumption and NF
10dB. Who would need a TL026? :-D

Jan

On Thursday, December 6, 2012 7:00:22 PM UTC-8, Arid ace wrote:
Who would need a TL026? :-D

Just someone that wants a part that's still in production :-)

Cheers -
Dana K6JQ

On Thursday, December 6, 2012 7:00:22 PM UTC-8, Arid ace wrote:

The data sheet of the TL026 doesn't mention the maximum input signal that can be

processed. For the SL612 that is 250 mV rms.

Actually, the datasheet mentions it - ~200mV.


Dana K6JQ

On Sat, 8 Dec 2012 01:39:46 -0800 (PST), Dana wrote:

On Thursday, December 6, 2012 7:00:22 PM UTC-8, Arid ace wrote:

The data sheet of the TL026 doesn't mention the maximum input signal that can be

processed. For the SL612 that is 250 mV rms.

Actually, the datasheet mentions it - ~200mV.


Dana K6JQ

With so many data sheet archives online, I could have hit the wrong one. But
what didn't fail to get my attention was the remark "Other Characteristics
Similar to NE592 and uA733". With those ICs I'm not only familiar but they are
from the era when customarily, the equivalent internal diagram was published so
uninitiated application engineers could use the IC in a fashion, not intended by
the designer. The NE592 and uA733 employ negative feedback which is at odds with
voltage controlled gain - unless the gain control is before the stage(s) with
feedback, and then the S/N under application of feedback deteriorates.
So the TL026 isn't my choice even if it's modern ;-)

Jan

On Saturday, December 8, 2012 6:31:35 PM UTC-8, Arid ace wrote:

With so many data sheet archives online, I could have hit the wrong one.

Since the TL026 is a currently-produced part by TI, there's no need to
sift through online archives. Just go to http://www.ti.com/ and look
up the part number.

But what didn't fail to get my attention was the remark "Other
Characteristics Similar to NE592 and uA733".

Fair enough. Of course, the TL026 *isn't* either of those parts,
and the statement suggests to me that the TL026 has input and output
characteristics similar to those non-AGC parts - relatively easy to use.
Nothing at all about internal architecture. Perhaps you're reading
something that isn't in the datasheet at all. Given how cheap the TL026
is, perhaps you might try one instead of an SL612 and see if your
assumption is true.

But, seriously, you're quite passionate about the SL612 and
that's a wonderful thing.

Cheers,
Dana K6JQ

On Wed, 12 Dec 2012 17:23:35 -0800 (PST), Dana wrote:

On Saturday, December 8, 2012 6:31:35 PM UTC-8, Arid ace wrote:

With so many data sheet archives online, I could have hit the wrong one.

Since the TL026 is a currently-produced part by TI, there's no need to
sift through online archives. Just go to http://www.ti.com/ and look
up the part number.

What remains is the large current consumption - typ. 22 mA.
For the SL612 the typ. value is 3.5 mA.


But what didn't fail to get my attention was the remark "Other
Characteristics Similar to NE592 and uA733".

Fair enough. Of course, the TL026 *isn't* either of those parts,
and the statement suggests to me that the TL026 has input and output
characteristics similar to those non-AGC parts - relatively easy to use.
Nothing at all about internal architecture. Perhaps you're reading
something that isn't in the datasheet at all. Given how cheap the TL026
is, perhaps you might try one instead of an SL612 and see if your
assumption is true.

Cost is a nonissue as is production. Another 30 mA just for the IF amplifier of
a noise blanker is an issue though.

But, seriously, you're quite passionate about the SL612 and
that's a wonderful thing.

Cheers,
Dana K6JQ

No, for the noise blanker it's the best solution. The IF minus impulse noise
will be processed by another no longer available IC, the TCA440. Its mixer and
IF combined have an AGC range of ~100 dB with max input to the mixer, 500 mV
rms, current consumption ~11mA. With the 30 dB AGC range of the 2nd mixer, 120
dB AGC range. That mixer will convert to 25 KHz, a nice value for razor-sharp
notch filters and ideally working (synchronous) demodulators. Why be satisfied
with less when it's so easy to design a radio that functions well with input
signals between 0.1 uV and 100 mV and yet has a low power consumption? ;-)

Jan