From: "Mike Dennison" <mike.dennison@rsgb.org.uk>
To: rsgb_lf_group@blacksheep.org
Date: Thu, 25 Jan 2001 16:55:41 -0000
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Subject: Re: LF: Stability
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> At 10:42 25/01/01 -0000, G3XDV wrote:
> >I am now using my IC-706 directly on 136kHz, with a pre-amp/filter
> >and this works fine.

> what antenna are you using for receiving ? 
> I'm using my transmitting antenna and found that I can add up to 40dB
> attenuation between antenna and RX (Kenwood TS440) before the
> bandnoise hits the RX noisefloor. I have 20dB attenuation all the time
> to prevent DCF39 from overloading the RX input (and causing IM
> products). I tried some preamps in my 'early days' on 136 but found
> them only a source of aditional IM products.

I use my normal Tx inverted-L for receiving most of the time. I think 
you are suggesting that I will have an overload problem with the IC-
706. In fact, this receiver is =very= insensitive at LF and must have 
a pre-amp to be of any use at all. I am using a pre-amp I bought at 
the RSGB HF Convention (I think designed by Dave, G3YXM?) and 
this has some very good front end tuned circuits. There is no sign of 
spurius responses.

When using the very sensitive Datong converter, I certainly needed 
to attenuate the input to avoid overload, and my loop antenna worked 
into it without any additional amplification.


Mike, G3XDV (IO91VT)
http://www.lf.thersgb.net