Topband: Slightly OT - amplifier noise

[John Kaufmann]

Steve,

An alternative is to do the cancellation with all passive circuitry.  You
can find some designs on the Web but you'll have to build them yourself. An
example (one that I built) is this one from WA1ION:
https://www.pa4tim.nl/wp-content/uploads/2011/02/passive_bb_phasing.pdf.
The drawback to the passive designs is the insertion loss.  The WA1ION
design works quite well but I've measured its insertion loss as about 12 dB.
That may not be acceptable in many situations, particularly on the higher HF
bands.

73, John W1FV  

-----Original Message-----
From: Topband
[mailto:topband-bounces+john.kaufmann=verizon.net at contesting.com] On Behalf
Of n2icarrl at gmail.com
Sent: Saturday, March 14, 2020 12:41 PM
To: Topband
Subject: Topband: Slightly OT - amplifier noise

This discussion of Hi Z amplifiers has been quite interesting. Excellent 
information from W1FV and K7TJR.

I have an RX amp question, related but slightly off-topic.

I have an MFJ-1025/1026 noise canceler. I like to use it on the higher HF
bands 
to cancel power line QRN. The noise is typically S3-S4, but I want it down
to S0 
to hear the bottom layer of stations. My sense antenna works fine, and the
QRN 
is canceled. However, the MFJ-1025 amplifier noise is quite significant,
often 
negating the QRN cancellation. The MFJ amplifiers are J310's. Any 
recommendations for something quieter ?

73,
Steve, N2IC

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