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Reviews Categories | Direction Finding equipment | Ron Graham 2m DF Receiver/Antenna Help


Reviews Summary for Ron Graham 2m DF Receiver/Antenna
Ron Graham 2m DF Receiver/Antenna Reviews: 2 Average rating: 4.5/5 MSRP: $(missing—add MSRP)
Description: An excellent one-piece 2-meter ARDF receiver set with high sensitivity, good selectivity, smooth varactor tuning, AM detection, an RF gain control and audio-pitch s-meter, designed to mount on the RGE model VHF-144 two-element HB9CV-style beam, which has steel-tape element ends covered with flexible tubing.
Product is in production.
More info: http://mackay.net.au/~ron/home.html
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WB6BYU Rating: 4/5 Jan 13, 2004 13:39 Send this review to a friend
A good DF receiver for 2m  Time owned: more than 12 months
Receiver comments first, antenna comments later...

I built a kit and used my first one in competition in 1997, then built a second for my wife. The two receivers have brought home 9 medals between them.

The kit is not difficult to build. Make sure you read the kit feedback notes on his web site, which clarify some rough spots in the manual. Allignment is made easier by the built-in audio S-meter. You can adjust the tuning range to your
preference.

Mechanically the box is solid. The 9V battery is held in an external clip to make it easy to change, but this exposes the battery wires to damage, and the battery can fall out if the clip gets loose. I recommend a wrap of duct tape over
the wires and battery. The power switch is easily knocked on during transport, so I always pull the connector off the battery as well - put in the best quality battery snap you can find, as this has required frequent replacement.

Receiver performance is relatively good, though the tuning can be a bit fast if you are trying to cover the whole 144 - 148 MHz range. (A 10-turn Knob-Pot is an excellent, though expensive, replacement for finer tuning. Simply using a larger knob will help a lot.) Bandwidth is on the wide side for crowded conditions: replacing the ceramic filter with a monolithic crystal filter from Mouser or Digi-Key will help, but of course that makes the tuning rate more critical. A voltage controlled oscillator (VCO) provides a tone whose pitch varies with the signal strength.

The receiver draws around 20mA. When the battery voltage drops below 7.5 it looses regulation and the VFO starts to drift badly. Fortunatly the no-signal VCO frequency is a good indicator of battery condition. Replacing the 78L05 regulator with an LM2931-5.0 or similar will keep the VFO stable to lower voltages: overall receiver performance still drops off, but it may be adequate to finish the hunt.

The audio S-meter (varible tone) is quite useful, and less than a 1dB variation in signal strength is quite detectable. The VCO signal goes ultra-sonic on strong signals, so you have to learn to reduce the gain if you can't hear the tone. The receiver is designed for AM reception: FM signals are readable using slope detection, though best audio is achieved by tuning slightly off the frequency of peak signal strength, and with the gain control set higher than when using the VCO. There is no provision for listening to the signal in one ear and the VCO tone in the other, which would be useful. As it is, if you are hunting in VCO mode you can not always tell if one signal goes away and another one comes on. (Been there, done that!)

Overall, not as fancy as the VK3YNG 2m sniffer, and not as ergonomic as the Altai-145 or the serious European competition receivers, but a nice self-contained package, and a giant step up in convenience from DFing on foot with a HT and attenuator.

ANTENNA

The HB9CV-style antenna is lightweight and compact, making it convenient for hand-held use. Unfortunatly we've measured the front/back ratio at only 6dB or so, which makes it easy to take a bearing in the wrong direction if you are not careful. The ends of the elements unscrew, but the inner element sections still stick out the sides of the boom, making it more difficult to fit the antenna in hand luggage when travelling. I now use a 3-element tape measure yagi with my receiver. My wife still likes her RGE antenna, though, as it is conveniently small, and the rigid inner element sections make it convenient to mount a map board to the antenna.

By the way, I mount the receiver BEHIND the back element, rather than between the elements as shown in the photos. This puts the center of gravity betweeen the receiver and the rear element, where it is fairly convenient to hold the receiver. This is much easier on your wrist. (The supplied handle is even worse!) It also shortens the needed headphone cable length (for those of us with long arms) and makes it easier to reach the controls for adjustment.
 
N5ZGT Rating: 5/5 Oct 5, 2001 18:55 Send this review to a friend
Sweet piece of gear.  Time owned: 0 to 3 months
I usually use an HT with a tape-measure beam and active attenuator for T-Hunting on 2-meters and have had great success. However, in becoming interested in ARDF-style hunts (all on foot, running against the clock), I decided that I'd rather have one piece of gear - total - rather than 3+ seperate pieces to hold on to while trying to take bearings. The Ron Graham is a solution. Everything is in one package - the antenna, the receiver, the attenuator, and the audio s-meter. With AM slope tuning and the VCO mode that allows for the audio s-meter, signals can be DFed very easily. Members of the Albuquerque Transmitter Hunters (including myself) bought up five of these sets and we are all having a ball with them!

As mentioned elsewhere in the T-Hunting product reviews, no single piece of DFing gear is the silver bullet for all DFing situations. That is the nature of DFing, and it doesn't mean the gear is bad. There will be times when a 3-element beam and HT will have more sensitivity than the Ron Graham, as an example, but there are times the Ron Graham will out-do a three element beam and HT. :-)

If you are looking for a new toy to add to your radio direction finding arsenal, this is one to consider! An 80-meter version is also available for ARDFers, though I have yet to step into the world of 80-meter direction finding. Happy hunting!
 


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