[NLRS] 2m IF rigs for uW's

[Dr. Gerald N. Johnson]

As WA5VJB how that rig has worked out. He suggested it when it first 
came out as a replacement for his favorite IC202 that was getting pricey 
from demand and difficult to use because of its limited frequency coverage.

I thought of using a Hohentweil 2m rig. Like the IC202 it uses VCXO for 
stability, but even narrower frequency range without the capability of 
shifting 1 or 2 MHz from 144.1 MHz like we used last weekend. I started 
building a kit, but haven't finished it. I stalled at winding the IF 
transformers with #38 wire. I bought one since then and have it working, 
but it developed an intermittent helical resonator filter and I wasn't 
able to take it apart but have repeatedly heated the intermittent pin 
with a soldering iron and it quit dropping out. I like the design, it 
uses single conversion with SSB filters right after the mixer and right 
before the product detector to narrow the IF stage noise. That is unlike 
the triple conversion 817 and 857 that passes wide band noise from the 
mixers and IF stages to the audio on receive, but the DSP low pass on 
SSB can filter that and I have an adjustable passive filter for speaker 
or headphone circuits that I have often used at home to remove ALL HF 
noise from the receiver output, whether its broad IF noise or DSP 
artifacts. www.geraldj.networkiowa.com/papers/speakerfilter.pdf

73, Jerry, K0CQ


On 9/23/2014 2:16 PM, Jon Platt via NLRS wrote:
>
>
>
> Finding low cost solutions for IF rigs to drive uW transverters is getting to be more of a problem.   The old 2m only multimode rigs are becoming harder to find as they slowly die off.  One possible solution is the MFJ (yes, MFJ) 9402.   Its a low cost ($310) 7 watt 2m SSB rig.  See http://www.mfjenterprises.com/Product.php?productid=MFJ-9402 .   Of course you get what you pay for but with a new FT817 going for about $670 it may be one solution, especially if you already have a good signal source for frequency calibration.
>
> 73, Jon
> W0ZQ
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