[Milsurplus] [ARC5] DAG HFDF Sense Antenna.

[W2HX]

> The 180 degree ambiguity is impossible to resolve without that sense antenna, BTW

There is an old fox hunting technique that does not require a sense antenna. You position your body between the antenna and the suspected direction of the emitter. If your body attenuates the signal then the fox is in the direction of your body from the antenna. If not, its 180*. Of course this technique might only be useful in a nearfield situation.

73 Eugene W2HX


-----Original Message-----
From: milsurplus-bounces at mailman.qth.net <milsurplus-bounces at mailman.qth.net> On Behalf Of Kenneth G. Gordon
Sent: Friday, April 2, 2021 11:00 AM
To: milsurplus at mailman.qth.net; ARC-5 <arc5 at mailman.qth.net>; David Stinson <arc5 at ix.netcom.com>
Subject: Re: [Milsurplus] [ARC5] DAG HFDF Sense Antenna.

On 1 Apr 2021 at 21:24, David Stinson wrote:

> Does anyone have or know of this sense antenna?
> It is the only piece missing from my DAG.
> I would pay or trade well for it.
> 
> TNX ES 73 DE Dave AB5S

Dave: Many years ago, I received a brand new DAG-1, with all accessories, from the MARS program. That receiver was excellent. I thoroughly enjoyed using it. It was very quiet and sensitive. It was beautifully made.

I gave it away along with a lot of other stuff, when I left Missoula, Montana. As is usually the case, I wish I still had it.

As I remember it, the sense antenna was simply one of those extendable whip-type antennas with a large male "pin" soldered into the end of it. The pin was a larger version of those "compressible" types which fit into a socket.

It wasn't all that hard to make one, if you didn't have the original one.

The 180 degree ambiguity is impossible to resolve without that sense antenna, BTW. I found that the DAG-1 worked very, very well for DFing.

Frequency coverage, as I remember it, was somewhat below the BC band to 18 MHz.

It had a BFO which exhibited good injection, but the receiver was somewhat susceptible to instability by mechanical shock.

I have watched for one to show up on that auction place, but so far, have never yet seen one.

I suspect that not too many were built.

Ken W7EKB
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