[Premium-Rx] Replacement mixers - WJ M9D - WJ 8716/8718/8888

Mon Feb 6 18:33:48 EST 2006

OK, I received responses from several interested parties on the list, probably enough interest for 15 units or so.

Now the bad news:  in lots of 10-25, the per unit price would be $60 each, 4-6 week lead time, plus shipping.  Again, these are custom-manufactured.  The company can and will do any WJ replacement, but the min is $150.   

Their old WJ catalog sez that the M9D is a 6 pin mixer - looking at the schematic for the WJ8888 that has one of these, it's a 8-pin.  And could anyone verify the exact size?  They will make it in any size/pin config we want, they just need to know.

Another question - what is the difference between this mixer and the WJ M6E?

Now, all that said, is there still interest? 

73 John
  ----- Original Message ----- 
  From: w3jn 
  To: premium-rx at ml.skirrow.org 
  Sent: Friday, February 03, 2006 9:17 PM
  Subject: Re: [Premium-Rx] Mini-Circuits SRA-3MH+

  I found a company that makes a drop-in replacement for the M9D - a dB and a half or two better loss, but same pinout, +20dBm LO, +30 dBm IP3.
  Problem is they're custom order with a fairly hefty minimum.  They haven't given me a per piece quote yet, but I'd like to see if there's any interest on the list.  Otherwise I might just order the minimum and hawk 'em on eBay if nobody here needs any.

  73 John
    ----- Original Message ----- 
    From: Carcia, Francis A HS 
    To: premium-rx at ml.skirrow.org 
    Sent: Wednesday, February 01, 2006 3:49 PM
    Subject: RE: [Premium-Rx] Mini-Circuits SRA-3MH+

    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

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    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

      "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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