RE: LF: PA0RDT antenna near a TX? Front end OK?

[Laurence KL7 L <hellozerohellozero@hotmail.com>]

Yep Mike, Andy et al - its a good point - I have a small pad on output of the power injector but haven't managed to blow up "a" front end yet and apparently Ive tried many times...didn't someone mod a PA0RDT into a small transmitter using the 5109 as the output ?  My SDR follows suit by flashing "SOS" in morse code...
 
 
Laurence KL7 L  enroute to G land
 

---

Date: Wed, 14 Oct 2015 21:36:20 +0100
From: andy.g4jnt@gmail.com
To: rsgb_lf_group@blacksheep.org
Subject: Re: LF: PA0RDT antenna near a TX? Front end OK?

My Procomm AAC-1 , when sitting under the 137kHz  antenna with 700 Watts feeding it (ie. about 7metres away at the shortest distance) , delivers a clipped waveform of 6V pk=pk into a 50 ohm load.   About +20dBm.   

The SDR I/Q objects and complains forcibly by flashing its red overload led, but it can survive that sort of level.  Any receiver that can't survive  100mW on its input is best put out of its misery, anyway.

'jnt

On 14 October 2015 at 21:24, Michael Sapp <wa3tts@verizon.net> wrote:

Laurence, Chris & All:  I did a test with my eprobe which is about 30 feet away from my HF elevated ground plane that has 65 ft radials a few years back. With 100W output on 40 meters. I was getting 1mw of RF power from the eprobe into a Boonton RF voltmeter. I was using a 1 inch wide by 12 inch long brass strip as the eprobe antenna at the time.  I would assume the eprobe may be able to generate more power than that at higher nearby transmitter power levels. Suitable overload protection for a receiver front end would appear to be prudent.....

 

73, Mike wa3tts

 

 

----- Original Message -----

From: Laurence KL7 L

To: rsgb_lf_group@blacksheep.org

Sent: Wednesday, October 14, 2015 2:56 PM

Subject: RE: LF: PA0RDT antenna near a TX? Front end OK?

Chris
 
I run up to 1Kw on 136kHz and up to 400W on 475kHz and "alive" Eprobes (L400 and PA0RDT variants) about 100-150ft away up at 30ft plus and not blown them up. They don't like it much of course and produce unwanted products during Tx but that not surprising.
 
Only FET failure to date has been down in Oklahoma from a nearby lightning strike.
 
 
Laurence
KL7L et al
 

>
>
> If I mount my PA0RDT clone on my mast stub, about 50 feet from my LF
> TX'ing aerial, is it likely to be damaged if powered on when TX'ing?
>
> Thanks.

> Best regards,
> Chris mailto:chris@chriswilson.tv
>
>