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
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