[NLRS] MGA-86576 - eBay?

Sun Dec 8 20:50:34 EST 2013

I'm pretty sure that all microwave DEMI transverters used mostly ERA 1, 
2, and 3 MMICs until about 3 years ago. So if you work a DEMI you are 
probably hearing those devices at work. The 86576 has been the first RF 
stage in the "normal" NF option with an ERA for the second stage before 
the mixer. Some years there was a low noise option that sometimes came 
with a 2 watt internal PA but the MMIC that did the low noise hasn't 
been available for some time now. Now all DEMI microwave transverters I 
think are 2 or 3 dB NF on receive and 10 to 20 mw transmit and depend on 
external preamps and power amps. It appears these designs have outlived 
the supply of parts though the NLB-310 is pretty good for replacing ERA 
over a wider frequency range. First RF stages look like mostly a 
mechanical problem for applying the VMMK-3803 since its so tiny. Its 
gain is good, its P1 is not as good, but its NF is nearly as good as a 
good FET. Places like Triquint have offered MMIC LNA, PA, mixers, and LO 
multipliers that could put a 10 GHz transverter in 3 or 4 MMIC in 5x5 mm 
QFN packages. Not something that would be very successful if offered as 
a kit. The filtering would take up way more space than the active 
devices and those same sources offer parts for 24 and higher.

73, Jerry, K0CQ

On 12/8/2013 1:36 PM, Zack Widup wrote:
>
>
> Also, the ERA-2 is spec'd to 6 GHz but its s-parameters are listed through
> 16 GHz. It has useful gain at 10 GHz. I've used them there. However, the
> noise figure isn't so great.
>
> 73, Zack W9SZ
>
>
> On Sun, Dec 8, 2013 at 11:53 AM, Dr. Gerald N. Johnson
> <geraldj at netins.net>wrote:
>
>>
>>
>> There is that risk. Its not a part most of us can test without installing
>> it in a circuit, and its stretched beyond ratings in the 10 GHz DEMI preamp
>> and transverter. It works quite well there. That would be the toughest test
>> for fakes.
>>
>> The MGA-86563 is the same chip in a different package that they are still
>> making. Trouble is the package parasitics limit its rated range to 6 GHz,
>> and its falling off rapidly there. I think the package can be twisted to
>> fit the footprint of the MGA-86576 for lower frequency applications than 10
>> GHz.
>>
>> The MGA-30989 is in a larger package but that limits its rated performance
>> to 6 GHz and the S parameters show 0.67 dB gain at 10 GHz. A suitable
>> substitute at 5760 and down, a dud at 10 GHz. And it its rated range the P1
>> is about +23 dBm, a power device with decent NF.
>>
>> The VMMK-3803 is a better part for 10 GHz operation for NF and gain over
>> the MGA-86976, but it is inconveniently tiny. Its in an 0402 package with
>> the ground pad in the middle and requires input bias to turn it on. That
>> package I'm sure won't stretch to the traces made for the 76 package (in
>> that HP/Agilent numbering scheme the last two digits of the part number are
>> package) and it doesn't appear to expose the pads for easy hand soldering.
>> It might work with tiny strips of copper foil added in dead bug position.
>>
>> Mouser has 490 of the MGA-86563 in stock at $2.60 each in small quantity
>> bulk and 3000 on order to be sold as cut tape for the same price.
>>
>> Mouser has 200 of the VMMK-3803 on order asking $7.60 each. They expect
>> delivery next March 19 and factory lead time is 26 weeks.
>>
>> Mouser has 794 of the MGA-30989 in stock at $2.68 each.
>>
>> Digi-Key has 448 MGA-86563 in bulk and 7296 in cut tape for $2.91 and
>> $2.99 each in single lots.
>>
>> DK has 925 VMMK-3803 in blk for $8.03 each and 9125 in cut tape for $8.28.
>>
>> DK has 233 MGA-30989 in bulk for $3 each.
>>
>> Pictures of the adaptations of these parts to existing DEMI boards would
>> be worth showing at Aurora and the rest of the season's VHF and microwave
>> conferences.
>>
>> The RFMD NBB-400T1 that DK has 13,516 in stock at $8.60 is in the same
>> package as the MGA-86576. It has a 4 dB NF vs the original 2.5 dB NF
>> rating. Rated to the same 8 GHz.
>>
>> The RFMD NBB-300T1 is rated to 12 GHz, but the NF is 5 dB. DK has a pile
>> in stock.
>>
>> I believe DEMI has been using the NBB 310 or NLB 310 (plastic package vs
>> ceramic) in transverters where NF isn't critical for a few years now in
>> place of the original collection of ERA parts. Rated past 10 GHz with 5 dB
>> NF and a bit more power out than the ERA used formerly.
>>
>> The RFMD SBW 5089Z is in a larger case rated to 8 GHz but with some
>> performance data to 10 GHz, not a super NF of 4 dB at 6 GHz. DK has in
>> stock.
>>
>> DK has some Hittite and Micro Tech parts to cover the 1 to 18 GHz range
>> all in QFN packages not interchangeable with the original part in question
>> and all just under $100 each. Except for the packaged Hittite part with
>> connectors for a mere $1601.28. They have only one of those in stock.
>>
>> There may be other suitable parts available from our most friendly
>> distributors Mouser and DK, I've searched enough for this morning.
>>
>> Some substitutions may need attention to input and output impedance
>> matching for optimum performance as well as changes in bias.
>>
>> 73, Jerry, K0CQ
>>
>>
>>
>>
>> On 12/8/2013 8:11 AM, John (JK) Kalenowsky, K9JK wrote:
>>
>>>
>>>
>>> I see a Chinese seller with 5 for<$18 (not sure if there's a risk of
>>> the parts being fakes) and a US seller with 2 for $17.
>>>
>>> Your mileage/eBay experience may vary. Some assembly required.
>>> Batteries not included. I have no relations with any of these eBay
>>> sellers. (Other disclaimers ad infinitum.) --JK
>>>
>>>
>>>
>>>
>>>
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