Message-ID: <5717D5A8.5050301@lineone.net>
Date: Wed, 20 Apr 2016 20:16:56 +0100
From: LineOne <dhchurch@lineone.net>
User-Agent: Mozilla/5.0 (Windows NT 5.1; rv:31.0) Gecko/20100101 Thunderbird/31.1.2
MIME-Version: 1.0
To: rsgb_lf_group@blacksheep.org
References: <5713E677.6040003@lineone.net>, <1071555453.20160418034309@chriswilson.tv>, <5716079B.30004@lineone.net> <57175921.22075.57BECD@mike.dennison.ntlworld.com> <885507565.20160420115147@chriswilson.tv>
In-Reply-To: <885507565.20160420115147@chriswilson.tv>
Subject: Re: LF: LF Receiving (was Alex (R7NT) reports)
Content-Type: text/plain; charset=windows-1252; format=flowed
Content-Transfer-Encoding: 7bit
Sender: owner-rsgb_lf_group@blacksheep.org
Precedence: bulk
Reply-To: rsgb_lf_group@blacksheep.org
Status: O

Of course, Mike reminded me, I assumed a receiver of choice will have 
things like agc fast, slow, on/off and so on plus a noise blanker. One 
reason for suggesting various tuned circuits depends on the receiver's 
front end selectivity and IM distortion.

Yes, Chris, I have an active whip with a gain of 100, it will provide 8V 
peak to peak output before clipping but that's still not enough and it 
suffers from IM! I'm drawing the circuit and adding a tuned circuit in 
order to model the response.
Could I suggest trying one of these "split field" antennas. I'm working 
on one now, it seemed to give good results just sitting on the workshop 
floor and will take care of the "front end " tuning. The only problem is 
mechanical, how to get a "barrel" of ferrite rods into a weatherproof 
container and mount it in a high place and, of course, it's directional.

Hugh, M0DSZ

On 20/04/2016 11:51, Chris Wilson wrote:
> Hello Mike,
>
> Wednesday, April 20, 2016
>
>
> I have been using a home built active antenna a friend bought me off
> Ebay, probably a close copy of the "proper" one I feel guilty about
> having a clone of. It's in a home built capped waste water pipe
> housing near the top of my lattice mast, on its fibreglass topmost
> section. I have found it does not work as well feeding my dedicated LF
> receiver, one of these:
>
> http://icas.to/lineup/idc-136ii-kit-eng.htm
>
>
>
> as does my transmitting, resonant aerial. That's a vertical with a
> horizontal quad loop as its top hat.
>
>
> This active antenna is just using the dedicated PCB section as the
> antenna, maybe I should add an external piece of stiff wire to it? I
> am certainly not plagued by any strong transmissions near here, it's
> normally our own electric fences that cause me issues.But sharing a TX
> aerial with a receiver is a pain. As is sharing my HF loop with an LF
> TX.... :( I need more aerials, but I do not need a divorce. Difficult!
>
> I would and could invest in a dedicated receiver for LF though,
> something hopefully better than the one in the link above. Space isn't
> an issue. Any suggestions for something commercially available? I am
> not incompetent at building stuff, I simply do not have the time at
> the moment, due to work. I have used my Kenwood TS-590 as an LF
> receiver, but again, as it's also the exciter form y LF amp, it's a
> pain swapping stuff about. I really want something I can leave on RX
> all the time like the IDC-136ii above, but better... Thanks.
>
>
>
> Best regards,
>   Chris  2E0ILY                          mailto:chris@chriswilson.tv
>
>   My part time LF grabber is at http://www.chriswilson.tv/grabber.html
>
>
>> Hugh's advice is excellent - adequate sensitvity, a resonant antenna
>> and good front-end filtering. I would add good dynamic range, an
>> effective noise blanker and ideally a way to reduce or switch off the
>> AGC. After fittng the filters, there should still be a large
>> difference in background noise when the antenna is connected.
>> Local noise is a major factor, and it may be necessary to have a
>> separate receive antenna, situated and oriented away from the noise
>> source.
>> Lastly, it can help to have a directional (preferably steerable)
>> antenna to reduce lightning noise away from the wanted direction.
>> Mike, G3XDV
>> ============
>
>
>
>
>