[amsat-bb] Re: 2 meter to 10 meter downconverter?

Edward Cole kl7uw at acsalaska.net
Fri Apr 6 08:23:57 PDT 2007

At 03:58 AM 4/6/2007, Tyler Harpster wrote:
>What's a good source of 2 meter to 10 meter down converters?  I just need to
>receive 2 meters, but my 706 is doing uplink duty on 435.  I have an old
>shortwave receiver that can do the listening to the AO-7 mode B downlink
>with a receive converter.

I can recommend the DEMI 144/28.  I just completed building the 
144/28K, which is the low-power xvtr kit.  It outputs 10mw in 
transmit for use with other xvtrs an designed to drive microwave 
units.  But I am using it in Rx-only to drive my SDR-IQ on 28-30 
MHz.  The receive-only version is identical without the transmit 
components and sold assembled for $170 (the kit I bought is also $170).

I had a couple boo-boos in the construction:  my first LO coil was 
too many turns and the oscillator would not run.  I apparently blew 
both the preamp and second receive mmic.  Replacing them I got -124 
dBm (0.14 uv) sensitivity in FM-mode.  My FT-817 is only -119 dBm 
(0.25 uv), so you can see this is pretty hot!  DEMI rates the 
converter at 1 dB NF and 17 dB conversion gain.  The LO uses a PTC 
heater and I have freq. stability as good as I can measure with an 
IFR-120 service monitor (1-Hz).

If wanting cheaper, you might check out TenTec.  They made a line of 
convertors and xvtrs at around $100 at one time.

Ed - KL7UW
  BP40IQ   50-MHz - 10-GHz   www.kl7uw.com
144-EME: FT-847, mgf-1801, 4x-xpol-20, 185w
DUBUS Magazine USA Rep dubususa at hotmail.com

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