SNIFFER MK4 by VK3YNG
Click for PDF instruction manual
Link to
VK3YNG Sniffer MK4
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3-WATT FOX BOX 4' off the ground with a 3' (5/8-Gain) ANTENNA |
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| MILES | SNIFFER MK4 | MOBILE C5900DA | LOOP ANTENNA on MK4 |
| 9.5 | #0 Noise floor is high. | Broke squelch once. | N/A |
| 7.5 | #0 Noise floor is high. | Broke squelch again. | N/A |
| 6.0 | #0 Starts to receive. | S-1 | N/A |
| 5.5 | #0 Good receive. | S-2 | N/A |
| 5.0 | #0 Real good receive. | S-3 | N/A |
| 4.0 | #1 | S-5 | N/A |
| 3.0 | #1 | S-6 | N/A |
| 2.5 | #1 | S-7 | N/A |
| 2.0 | #1 | S-8 | Just starts to DF. |
| 1.5 - 1.8 (1.65) | #1 | S-9 | Good DF qualities. |
| 1.0 - 1.5 (1.25) | #2 | S-9+ | Great DF qualities. |
| 0.5 | #3 | S-9+ Solid | Great DF qualities. |
| 0.1 | #4 | S-9+ Solid | Great DF qualities. |
| 350 feet | #5 | S-9+ Solid | Great DF qualities. |
| 110 feet | #6 | S-9+ Solid | Great DF qualities. |
| 30 feet | #7 | S9-+ Solid | Great DF qualities. |
| Rule of
thumb: 3dB is double the power and 6dB doubles the distance. (However, I
can't find a document-able source for this rule). So if Henry-KF6PCE was the FOX, running 30-watts into a +10db yagi, he would be effectively running 300-watts. That is a signal 100 times stronger than my 3-watt test transmitter. That means your should multiply all my mileages by 3.4 |
| Sniffer MK4 @ 3-Watts. | Sniffer MK4 @ 300-Watts. | |||
| #0 | 6.0 miles. | #0 | 20 miles. | |
| #1 | 4.0 miles. | #1 | 14 miles. | |
| #2 | 1.3 miles. | #2 | 4.5 miles. | |
| #3 | 0.5 miles. | #3 | 2 miles. | |
| #4 | 0.1 miles. | #4 | 0.4 miles. | |
| #5 | 350 feet. | #5 | 0.1 miles. | |
| #6 | 110 feet. | #6 | 374 feet. | |
| #7 | 30 feet. | #7 | 102 feet. | |
| The SNIFFER MK4 is as sensitive as most of
my HT's and more sensitive than my ICOM R3. I think the SNIFFER will be used
as my initial bearing receiver, as well as my U-R-Here radio and close-in
sniffer. Rich-KN6FW checked the sensitivity of the SNIFFER MK4 and came up with .1uv ... my Icom R3 is .25uv. The only draw back to the SNIFFER's receiver is it's selectivity of 16khz verse the Icom R3 at 12khz. This can be a problem in high RF environments, such as the Fremont Start Point and Repeater Hill Tops. I found that manually selecting attenuation level-1 on the SNIFFER (if you can still hear the fox), eliminates selectivity issue. As you can see from my above SNIFFER calibration, you can hear the fox 4-miles away in attenuation level-1. If you use a +10dB gain yagi, you can gain another 6-miles. If you are elevated, you can gain even more distance. As a U-R-Here radio, the SNIFFER steps are a little wide in the beginning. You tend to travel a large distance before it begins to step through attenuation but, when you get close to the fox, it exceeds the Icom R3. The SNIFFER has 5 more attenuation steps beyond the R3 and can get you within feet of the fox. The best I could do with the R3 is park and walk 528 feet (1/8 mile) or in the case of a high powered transmitter, park and walk 1/2 mile. The SNIFFER can keep on detecting the fox and let you know within feet, if you have passed it. Sniffing close-in is now a joy. No more messing around with external attenuators and saturated radio's when you are on top of the transmitter but, still can't find it. The new ARROW LOOP ANTENNA in combination with the SNIFFER will be great when hunting in tight quarters (like Shopping Malls). To be continued... |
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To help get a feel of my MK4 U-R-Here
distance predictions, I made some maps of my findings. |
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