SXA-389B replacement - MAAMSS0049?

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MightyGuru
 
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SXA-389B replacement - MAAMSS0049?

Post by MightyGuru »

**UPDATED READ BELOW**
I have been researching replacements for the SXA-389B that are cheaper and easier to acquire. So far the BGA-6589 looks fairly close. It's only drawback is it requires a series bias resistor (389 is internally biased). It is however internally matched for 50 ohms. :) This part can be obtained through Mouser for $2.38 or DigiKey for $2.25.

Has anyone found a better raplacement? Thoughts?

My estimated bias resistor value with Vcc=5V would be ~1.8 ohms.

**UPDATED READ BELOW**
Last edited by MightyGuru on Wed Mar 19, 2008 9:02 am, edited 1 time in total.

inh
 
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replacement

Post by inh »

I just checked the specsheet - it looks much weaker than even the 389...

MightyGuru
 
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Re: replacement

Post by MightyGuru »

inh wrote:I just checked the specsheet - it looks much weaker than even the 389...
Any suggestions?

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Post by MightyGuru »

:arrow: ****What spec do you rely most on when selecting/comparing amplifier chips? P1db, OIP3, or just the Gain?*****

Nevermind, P1db seems to be the best spec for power out, coupled with the gain figure.

My quandry all along was why my measured output was much lower than the specified output of the MMIC device. This is largly due in part to the output of the VCO (and output matching). The ROS-2500+ only outputs 6.5dbm to drive the SXB-4089B. With a gain of 15db @ 1960MhZ total output is 21.5dbm = 141mW (damn close to what I am measuring).

MightyGuru
 
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Re: replacement

Post by MightyGuru »

inh wrote:I just checked the specsheet - it looks much weaker than even the 389...
OK, I think I've found a NICE replacement! Take a look at MACOMM's MAAMSS0049 and MAAMSS0050 :shock:

The biggest drawback is the drive current required.

MAAMSS0049 (@1900MhZ) $3.88ea
Gain - 15.5dB
P1db - 28.5dbm (708mW)
V - 5V
Id - 325mA


MAAMSS0050 (@1900MhZ) $6.65ea
Gain - 14dB
P1db - 30dbm (1W)
V - 5V
Id - 550mA :!:

I'm also looking at Z-Comm's V585ME52 VCO. 1350-2350MhZ, same footprint, 12V, with an output of 12.5dbm 8)

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405nm
 
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Post by 405nm »

Played with any of these yet? I'd be interested to know how they worked out....

MightyGuru
 
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Post by MightyGuru »

powerpants wrote:Played with any of these yet? I'd be interested to know how they worked out....
Don't waste your time. Stick with the SXB-4089Z. Burned up 8 of these MA MMIC's testing.

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Post by WBVenom »

Don't waste your time. Stick with the SXB-4089Z. Burned up 8 of these MA MMIC's testing.
SXB-4089Z? I thought the amp gainstage part number was SXA-389BZ. Where did SXB-4089Z pop up from:?:

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405nm
 
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Post by 405nm »

it's a more powerful amp that People Who Know What They're Doing can swap out for the original amp chip.

it requires some creative passive placement and draws a lot more current from the battery, though.

i'm going to try it once I finish testing my WB built to the original spec and determine if i am a Person Who Knows What He's Doing.

MightyGuru
 
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Post by MightyGuru »

Well worth the effort. And now available through DigiKey. :wink:
I would recommend upgrading your +5V regulator to accomodate the added current.

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405nm
 
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Post by 405nm »

Thanks for the tip......are you using the LM2731Y for the upgrade?

I've got some coilcraft samples on the way, so the hacking will begin as soon as they get here....

Would it be possible for you to post some pictures of how you rigged the passives on the SXB?

MightyGuru
 
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Post by MightyGuru »

powerpants wrote:Thanks for the tip......are you using the LM2731Y for the upgrade?

Would it be possible for you to post some pictures of how you rigged the passives on the SXB?
Yes, I used the LM2731Y.

whitey
 
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Re: SXA-389B replacement - MAAMSS0049?

Post by whitey »

powerpants wrote: Would it be possible for you to post some pictures of how you rigged the passives on the SXB?
I attempted to get 2 of the SXA-389B from Sirenza and I had no luck. I was told they only sold them in mass. Have any of you had luck with these replacement parts (SXB-4089Z)? If so some reports would be appreciated at your convenience. School just ended for the semester and I'm looking forward to this project.

nova
 
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Re: SXA-389B replacement - MAAMSS0049?

Post by nova »

the P1 is 21 dBm @ 850 and 20 dBm @1950 MHz

current drain is only 70mA compared to 110mA for sxa-389b and 225mA for sxa-4089


say you want 21 dBm as output power and the output from vco is 7dBm you need a -4dB pad

and for 22dBm -7db pad

may be this the amplifier you need

digi key parts# 568 - 2075 - 1 - nd

hope this helps

steve

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sheepke
 
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Re: SXA-389B replacement - MAAMSS0049?

Post by sheepke »

What do you guys think of this one: RF3809 2W 450-2500Mhz HBT GaAs PRE-DVR
The only thing i don't know is what PRE-DVR stands for.
What's the difference between the SXB-4089Z and the RF3809 ?

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