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Author Topic: ICs for RF amp and mixer?  (Read 2527 times)
NU9J
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Posts: 109




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« on: March 18, 2013, 05:04:35 PM »

I was wondering if any of you would tell me some good ICs for a VHF RF amp, IF amp, and mixer that I could get on mouser or digikey.

Thanks a lot!
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~Philip
W2AEW
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« Reply #1 on: March 18, 2013, 06:04:43 PM »

I was wondering if any of you would tell me some good ICs for a VHF RF amp, IF amp, and mixer that I could get on mouser or digikey.

Thanks a lot!

Does it have to be Mouser or Digikey?  For a VHF RF amp, it's more common to design one using a suitable BJT or FET.  For an IF amp, traditional common ones are the MC1349 or MC1350 (but you didn't state what IF frequency). For a mixer, a common device would be NE602A or NE612A (also same devices with SA prefix instead of NE). These can be found at places like http://kitsandparts.com/
« Last Edit: March 18, 2013, 06:07:29 PM by W2AEW » Logged

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NU9J
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Posts: 109




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« Reply #2 on: March 18, 2013, 07:47:23 PM »

Thanks for the reply! I really like your youtube videos BTW. I will design the IF for 10.7 MHz.

The biggest concern for me is the RF amp; I've never built one. The NXP BF1202 seems like a good choice, apparently able to give 34 dB gain at 200 MHz in a common-source configuration. Is this enough before feeding to a mixer? The S1 level corresponds to -141 dBm, so with a single stage I'd be feeding -107 dBm to the mixer. What's typical to feed a mixer?
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~Philip
G3RZP
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« Reply #3 on: March 19, 2013, 01:10:06 AM »

It all depends on what you are wanting in terms of noise figure, gain compression point, intermodulation performance and how good the phase noise of the local oscillator is, since with high phase noise, the other parameters are effectively compromised.
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NU9J
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« Reply #4 on: March 19, 2013, 08:24:52 AM »

It all depends on what you are wanting in terms of noise figure, gain compression point, intermodulation performance and how good the phase noise of the local oscillator is, since with high phase noise, the other parameters are effectively compromised.

To be honest, I don't really know. I am just starting the design. Is there a canonical document for superhet design considerations?

I am tentatively planning to use the Si570CBC programmable CMOS XO. This one has about 31.5ppm of total stability and about 0.5ps of phase jitter.
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~Philip
N3QE
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« Reply #5 on: March 19, 2013, 12:10:08 PM »

You might want to look at the KK7B's RCX2 2-Meter converter for a very home-brewable RF amp + mixer + LO chain + IF amp. Other than the toroids, every part will be easily available from Mouser or Digikey. A very available microprocessor crystal could be used in LO chain with a very slight tweak in IF frequency. Toroids are easy from kitsandparts, amidon, or others.

No IC's, but lots of J310's!!! Very happy. http://www.kangaus.com/Documentation%20files/RCX2%20Documentation.pdf

« Last Edit: March 19, 2013, 12:20:45 PM by N3QE » Logged
G8HQP
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Posts: 123




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« Reply #6 on: March 20, 2013, 03:57:39 PM »

Quote
To be honest, I don't really know. I am just starting the design. Is there a canonical document for superhet design considerations?
How many HF radios have you designed? I would not start with VHF. Disappointment is the most likely outcome.

Amateur receivers are well-described by Doug DeMaw W1FB's books.

For a professional look there is Ulrich Rohde, although his books are expensive.

Other options are ARRL or RSGB handbooks, and some articles in their magazines.
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WB6BYU
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Posts: 13231




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« Reply #7 on: March 20, 2013, 05:52:30 PM »

The old Solid State Design for the Radio Amateur, and the newer
Experimental Methods in RF Design, are both excellent books for
ham construction projects.  The former is out of print, the latter is not
cheap (and I don't know if it is still in print.)  W7ZOI had a hand in both
of them:  you'll find some notes on his site here:  
http://w7zoi.net/index.html

A number of his ideas show up on the QRP Home Builder page here:
http://www.qrp.pops.net/

The choice of devices will depend somewhat on the desired application.
The SA602-type mixers are good for low powered equipment, but don't
have the strong signal handling capability that one might want for a
major contest receiver in a strong signal area.  The BF998 dual-gate
MOSFET is readily available for a front end device, as shown here:
http://lea.hamradio.si/~s53ww/4xbf998/4xbf998.  

In many cases more common parts such as the J310 FET are adequate.  
It all depends on what noise figure you need for your application, how
strong of a signal you need to be able to tolerate, any limitations on
power dissipation or current draw, etc.  For a high-performance
receiver you may need a diode mixer, which will require a high level of LO
drive.

Some further links of interest:
http://techdoc.kvindesland.no/radio/vhfuhftrx/
http://www.i1wqrlinkradio.com/antype/preamplifiers.html
http://www.pg1n.nl/articles.php?lng=nl&pg=153
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