5ft Comet active antenna

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KC8ESL

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Looks awesome for those runs that require really long lengths of coax between antenna and radio.

On the other hand, if you use this 6ft from the radio, a mouse fart would overload the receiver.
 

SCPD

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Looks awesome for those runs that require really long lengths of coax between antenna and radio. On the other hand, if you use this 6ft from the radio, a mouse fart would overload the receiver.

What on Earth are you talking about? This is not meant for some $50 shortwave portable. :roll:
 

ka3jjz

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It doesn't look like there's any way to vary the gain if conditions warrant it. Even on a good desktop, I would question using 30db of gain (and we all know that db without a reference point is not very meaningful, however...) on 6 Mhz on an East Coast evening. Overloading is a very real possibility.

It does say gain is 3-7dbi, which is way more meaningful - but then how the heck are they coming up with 30db of gain on HF?

Something fishy here....

Mike
 

KC8ESL

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Mike, I think the 30 dB figure is the make up gain from the preamp sitting at the antenna, where it should be.... This is a very cool piece IF the user can use it correctly.

6 ft of coax from the antenna to radio WILL overload a receiver. 100ft or more of RG8x would be nicely balanced for this antenna up around 900MHz.
 

Token

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It doesn't look like there's any way to vary the gain if conditions warrant it. Even on a good desktop, I would question using 30db of gain (and we all know that db without a reference point is not very meaningful, however...) on 6 Mhz on an East Coast evening. Overloading is a very real possibility.

It does say gain is 3-7dbi, which is way more meaningful - but then how the heck are they coming up with 30db of gain on HF?

Something fishy here....

Mike

The operating range is 500 kHz to 1.3 GHz and the stated antenna gain is 3 to 7 dBi. Separately the pre-amp is quoted as 30 dB gain on HF and 12 dB gain above 900 MHz.

I have no issue with the pre-amp having 30 dB at HF and 12+ dB above 900 MHz, those are easy numbers to chew on. But the 54 inch tall antenna itself, sans amp, does NOT have 3 to 7 dBi across the range of 500 kHz to 1.3 GHz.

This sounds like marketing math to me, maybe all true in some way, but definitely not true when taken as a whole.

For example, the little antenna when combined with the 30 dB pre-amp (at HF) might produce about 3 dBi of systemic gain in the HF range (assumed antenna gain of -27 dBi combined with amplifier gain of +30 dB). But this assumption that the 3-7 dBi is system gain falls apart as you move up in freq. If the amplifier is 12 dB or more above 900 MHz does that mean the antenna without amp is -5 dBi around 900 MHz? So in no frequency range does the antenna exhibit near unity gain?

I think it is a simple case of not enough documentation and someone wants to get advertisement out now.

T!
 

WM7C

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08/18/15.
NCG-Comet USA has informed us this product development is on indefinite 'hold'.
We will post any new announcements.
 

jackj

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For what it is worth, there are several discone antennas available from different manufacturers that will cover that frequency range. You could pair one up with a antenna preamp and get the same performance. Google discone antenna.
 

ka3jjz

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To bring this back to topic - kandrey, what is your situation? Can you put something outdoors? What are you using on HF?

There are many widebanded (HF) designs - even the venerable PAR end fed- that work quite well and don't need a whole lot of space...Mike
 
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