[Premium-Rx] Mini-Circuits SRA-3MH+

[Carcia, Francis A HS]

Hi All
I use the RAY 6 and SRA 1H both good mixers. SRA 3 should also do a good
job. I tack solder the case to ground in all cases.   The RAY 6 works fine
between plus 14 to plus 24 DBM LO. Racal used the RAY6 in their DF
receivers. fc

  _____  

From: premium-rx-bounces at ml.skirrow.org
[mailto:premium-rx-bounces at ml.skirrow.org] On Behalf Of Ahmet Gundes
Sent: Wednesday, February 01, 2006 2:55 PM
To: Craig Anderson Ext 1365; premium-rx at ml.skirrow.org
Subject: Re: [Premium-Rx] Mini-Circuits SRA-3MH+



 

I used a couple different types of mixers. One had a lower LO drive of +7
dBm ( made by Synergy ) and I had to put a pad between the mixer and the LO
drive.  Another one was an RF Prime ( no longer in business ) +17dBm mixer.
Results are the same without getting into usual IMD performance, etc... of
mixers under normal usage conditions. But I still think that using a Pad
between mixer and LO Drive helps clean up the signal and get a bit lower
Noise ( in my opnion ! ). But then again lower LO power mixers have lower
IPs.

Original mixer used by WJ, M9D, has a more limited range on the lower
frequency side according to catalog info. It is rated at RF 2 - 400MHz.
Also the LO Drive power is rated at +20dBm and an Intercept point of +30dBm.
I checked a few 8718's and their LO drive power levels vary from unit to
unit.

I am wondering if the 8718's that have a front plate with a 15kHz - 30MHz
range indication are using the M9D also or a different mixer for better
lower frequency coverage.

I believe Mini Circuits also might have a mixer which will exactly match the
M9D's PinOut configuration so this way you do not have to cut any trace on
the PCB. 

A funny design "flaw" in my opinion is that this First mixer is not
"properly" grounded and the input side uses the connector's contact with the
case for grounding as opposed to also using the PCB trace like the other
pins that are grounded via the pcb traces.  When installing the new Mixer, I
would ground the Case as well and connect all grounded pins to one spot on
the PCB. 

Not to mention an ineffective Surge/Lightning protection used in the Low
Pass Filter module.  I wonder why they even installed it.

Regards,

Ahmet


 

Has anyone had experience using the SRA-3MH+ mixer in place of the standard
WJ M9D mixer?  It appears that Mini-Circuits has improved both the mid-band
conversion loss and lower cutoff frequency from the older SRA-3H commonly
used to replace the WJ M9D in the 87xx series radios. I have one with a
blown M9D and need to replace it soon. 

 

"Old"   Mini-Circuits SRA-3H, RF 0.05-200 MHz, IF DC-200 MHz, P_LO=17dBm,
Loss=5.18dB, Model features SP, IMT
BM_1147417
BM_1147419"New" Mini-Circuits SRA-3MH, RF 0.025-200 MHz, IF DC-200 MHz,
P_LO=13dBm, Loss=4.77dB, Model features SP, IMT

 

How much trace cutting is needed?

 

W9CLA

 

Craig L. Anderson, Ed.S.

Vice President - Administration

Saint Paul College

Minnesota State Colleges & Universities System

Voice:  651.846.1365

Fax:     651.846.1675

 

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