6788	2011-11-07 18:37:00	Ray	Part similar to MC1350
Message	Date	From	Subject
Is there a newer part with performance similar to the MC1350 (surface mount is OK)? I know the MC1350 is still available from different sources but I don't really want to design something around it. I know the AD603 can easily exceed the MC1350 specifications but it is rather expensive. I don't actually need a full-blown IF amplifier with AGC. I'm just wanting to get 35-40 dB gain at one frequency below 30 MHz. I have thought about trying a couple of MAR-6 parts in cascade. Noise figure is not a big concern in my application. Would two copies of EMRFD Fig 2.57 accomplish the same thing? Ray AB7HE
6790	2011-11-07 23:11:59	Lasse	Re: Part similar to MC1350
One problem might be oscillation at UHF.. the MAR-6 is good up to several GHz, and having 40 dB gain means you must have good layout and decoupling! You may be better of, building a class A feed back amp with say 16 dB and use three of these. Should be much easier to tame. BTW MAR-6 got pretty good NF... /Lasse SM5GLC Ray skrev 2011-11-08 03:36: > Is there a newer part with performance similar to the MC1350 (surface mount is OK)? I know the MC1350 is still available from different sources but I don't really want to design something around it. I know the AD603 can easily exceed the MC1350 specifications but it is rather expensive. > > I don't actually need a full-blown IF amplifier with AGC. I'm just wanting to get 35-40 dB gain at one frequency below 30 MHz. I have thought about trying a couple of MAR-6 parts in cascade. Noise figure is not a big concern in my application. > > Would two copies of EMRFD Fig 2.57 accomplish the same thing? > > Ray > AB7HE >
6791	2011-11-08 05:42:27	Ashhar Farhan	Re: Part similar to MC1350
just assemble your own differential amp with three discrete bipolars. the circuit is in emrfd. - farhan
6792	2011-11-08 07:05:03	Alex P	Re: Part similar to MC1350
Look at the MC1496 as a substitute for the 1350. I've used 2 MAR devices AND on another project, 2 1350's in cascade in the same (small) metallic enclosure and most always get oscillations. Solution is to reduce the chain gain. Concur with another member's comments about having separate amplifier stages, preferably in separate enclosures. Alternate is to build them 'open face'
6793	2011-11-08 08:01:28	Ray	Re: Part similar to MC1350

6794	2011-11-08 08:07:38	William Carver	Re: Part similar to MC1350
Interesting to consider alternatives but if you want an AGC-able amplifier, why? The MC1350 is still a great part for an AGC amplifier. Not as linear an AGC characteristic, but plenty good for 99% of our applications. Lower NF than the AD600/AD603 and order of magnitude lower cost. But look at Wes' JFET gain-controlled amplifier for a discrete alternative. If all you want is gain then there are any number of alternatives. W7AAZ
6795	2011-11-08 08:44:17	Alberto I2PHD	Re: Part similar to MC1350

6796	2011-11-08 09:06:04	Alex P	Re: Part similar to MC1350
Ray, You are correct. That will teach me to rely on memory before having morning coffee. The part I intended was MC1490P..."Wideband Amplifier with AGC" as a sub to the 1350. Fig 2.57 with the 2N3904 looks like a good candidate. That part was pretty robust as an interstage power amp after a J309 vfo that was built a while back. I'd be interested in the results of the reverse connecti
6797	2011-11-08 09:12:49	bobtbobbo	Re: Part similar to MC1350
When using a 1349 1nstead of a 1350 do not ground pin 3. Bypass it with a .1uf cap. The 1349 is supposed to have slightly more gain than the 1350. Bob, K1AO
6798	2011-11-08 09:26:25	William Carver	Re: Part similar to MC1350
Actually the MC1349 is a better part than the MC1350P. It "delays" application of AGC to the input stage at very low gain control current so the NF doesn't deteriorate for small signals. But it seems the MC1350 has become "standard", while the MC1439 seems to have disappeared from hobbiest channels..... W7AAZ On Tue, 2011-11-08 at 17:44 +0100, Alberto I2PHD wrote: > >
6799	2011-11-08 09:33:19	Lasse	Re: Part similar to MC1350
Ray skrev 2011-11-08 03:36: > I'm just wanting to get 35-40 dB gain at one frequency below 30 MHz. I have thought about trying a couple of MAR-6 parts in cascade. Noise figure is not a big concern in my application. > Let's just read once more what Ray wants... a single frequency (<30MHz), ~40-ish dB of gain and no AGC. Things not mentioned are: linearity, and power consumtion. Guess a few BF199 with tuned circuits would do nicely... still using feedback amps with discrete transistors will give a flat gain over frequency but not way over 100 MHz. Not sure but I bet that the MC1490/1590 are even "more obsolete" than the 1350! And the 1349 is turning into hens teeth too! Not to mention the Plessey stuff :D /Lasse SM5GLC
6800	2011-11-08 09:58:22	Ray	Re: Part similar to MC1350
Lasse, You are correct. The requirements are simple. Just roughly 40dB of gain at a single frequency, AGC not required. Linearity is not really a requirement as this is a simple receive application. Power consumpti
6801	2011-11-08 11:00:33	Steve Ratzlaff	Re: Part similar to MC1350
This guy has advertised both MC1349 and 1350 for quite awhile. http://kitsandparts.com/parts.php Steve ----- Original Message -----
6802	2011-11-08 11:48:27	William Carver	Re: Part similar to MC1350
I'll be darned. Thanks for the link, Steve. My IF amplifier drawer was near bottom on the 1349P. I see he has DIP NE602, too. Not that I need any more of those puny things, but thought NE and DIP were no longer produced. W7AAZ On Tue, 2011-11-08 at 11:00 -0800, Steve Ratzlaff wrote: > > This guy has advertised both MC1349 and 1350 for quite awhile. > http://kitsandparts.com/parts.php > > Steve > > ----- Original Message ----- >
6803	2011-11-08 15:01:42	William Carver	MC1349P v.s. MC1350P gain control inearity
I realize that AGC was not needed in the MC1350P "replacement" topic. Nonetheless, having passed on Motorola's claim that the MC1349P was an improved MC1350P I felt I should mention what I see in the data sheets. The MC1349P data sheet shows both Vagc and Iagc versus gain. BOTH curves are highly nonlinear so either one will have a large variation in AGC gain (dB/volt, or dB/amp) over the 70-80 dB range. This is one component of the "loop gain" in an AGC feedback system. I took a ruler and estimated the highest slope of the line at two points: after about 20 dB of gain reduction, it is very steep, almost vetical, and 20 dB/uA. The low-slope point occurs after 30 to 40 dB of gain reduction, and that slope is 0.13 dB/uA. That is a 160:1 difference in loop gain, which would make it very, very difficult to get a stable AGC system with consistent dynamics. They don't show gain v.s. AGC current for the MC1350P, only gain v.s. AGC voltage. But doing the same slope estimation on the voltage data gave numbers that varied 4:1 over the 70 dB gain control range. So the MC1349 might be improved in NF and have a wider gain control range, but in an AGC loop I will take the MC1350 ANY DAY. I've used the MC1350P and gotten nice sounding AGC without any noticeable overshoot or undershoot. The AD600/603 have absolutely linear gain v.s. control voltage which makes it easy to design a traditional feedback system and get AGC that doesn't have "thumps" and "pops" from overshoot and undershoot. The price is very high noise figure and relatively astronomical cost. W7AAZ
6804	2011-11-08 15:12:13	kb1gmx	Re: Part similar to MC1350

6805	2011-11-08 15:54:21	Ray	Re: Part similar to MC1350

6807	2011-11-08 18:29:25	ehydra	Re: Part similar to MC1350
William Carver schrieb: > Interesting to consider alternatives but if you want an AGC-able > amplifier, why? > > The MC1350 is still a great part for an AGC amplifier. Not as linear an > AGC characteristic, but plenty good for 99% of our applications. Lower > NF than the AD600/AD603 and order of magnitude lower cost. > Where is the low price for MC1350 ? > But look at Wes' JFET gain-controlled amplifier for a discrete > alternative. > > If all you want is gain then there are any number of alternatives. Consider to learn from here: http://www.mydarc.de/dc4ku/ZF.pdf and all the other docs there. - Henry -- ehydra.dyndns.info
6808	2011-11-08 18:52:19	Ray	Re: Part similar to MC1350
Unfortunately I don't speak German so that website doesn't help.
6809	2011-11-08 19:22:56	William Carver	Re: Part similar to MC1350
Henry asked: > Where is the low price for MC1350 ? http://kitsandparts.com/parts.php has three MC1350P for $5. > > But look at Wes' JFET gain-controlled amplifier for a discrete > > alternative. > > > > If all you want is gain then there are any number of alternatives. > > Consider to learn from here: > http://www.mydarc.de/dc4ku/ZF.pdf > > and all the other docs there. > > - Henry very nice design. Wish I could read German. The voltage v.s. attenuation of the PIN diode attenuator is monotonic with a gradual and moderate change of slope (slope = AGC gain) over the whole range of signals. So it should be relatively easy to make a very nice sounding AGC. W7AAZ > -- > ehydra.dyndns.info > > > >
6810	2011-11-08 20:34:40	ehydra	Re: Part similar to MC1350
I don't see big problems if one is really interested. Just let it auto-translate by Google or another. Try this: http://translate.google.de/translate?hl=de&sl=de&tl=en&u=http%3A%2F%2Fwebcache.googleusercontent.com%2Fsearch%3Fhl%3Dde%26gbv%3D2%26q%3Dcache%3AEl9KKPVgkAsJ%3Ahttp%3A%2F%2Fwww.mydarc.de%2Fdc4ku%2FZF.pdf%2Bhttp%253A%2F%2Fwww.mydarc.de%2Fdc4ku%2FZF.pdf%26ct%3Dclnk The output looks reasonable. - Henry Ray schrieb: > Unfortunately I don't speak German so that website doesn't help. > >
6811	2011-11-09 13:38:48	kb1gmx	Re: Part similar to MC1350

6818	2011-11-11 13:56:25	ehydra	Re: Part similar to MC1350
Yes, this works. Another benefit of the 602 is that it don't want to oscillate on the false pins :-) - Henry kb1gmx schrieb: > Consider that the 602 is a gilbert cell (or more correctly analog > four quadrante multiplier) and the input attenuator is the same circuit for the 1350 it would appear to me that getting the 602 > to give gain (good for about 17db) and act as attenuation > would be possible. The oscillator input pin (6) would be the gain > control pin. -- ehydra.dyndns.info