6600/M Bandpass Filters

Mark Griffin

GE Flexradio,

I asked the question to Michael yesterday regarding which would be a better contesting radio. Would it be the 6400 or 6600. He answered my question by saying the 6600 would be due to the bandpass filters. Perhaps I don't understand bandpass filters enough, but I thought they applied to if one was operating SO2R or you were operating close to another operator. Am I wrong in my assumption? Thanks!

Mark Griffin, KB3Z

bahillen

For contesting I would agree with the 6600. The filters will reduce other signals that can cause interference you may not expect. The better your antennas the more important the filtering is.

The phase noise is better with the 6600.

The most important to me is the second SCU giving you two separate antennas. One could be a directional antenna with a vertical or receive antenna on the second SCU. Also it allows monitoring activity on a separate band.

You may not see a need today for the way you operate but as you have new ideas or different contest you are going to want the capability.

I felt that the cost difference is less because the 6400 antenna tuner is a $300 option that is standard with the 6600.

73

Bill W9JJB

KD0RC

Hi Mark, Yes, your assumption is correct. The 7th order filters of the 6600 give you 50 dB of isolation from signals on bands other than the one on which you are operating (including AM broadcast). If you contest with multiple stations in close proximity on different bands, this could be a critical factor in choosing the 6600 over a 6400. Another key point in favor of the 6600 is as Bill describes, above - the second SCU. If you want to operate SO2R, you can run two bands at the same time using two different antennas.

What kinds of contesting are you interested in? The answer will help determine whether the 6400 is adequate, or if you would be better off with the 6600.

Mark Griffin

Thanks BIll and Len for your advice.

My contest station is as follows, I have a DXE 8 port antenna switch out on my tower and have one coax coming into the station. I have an EC-8 switch in the shack so I can change antennas. For receive antennas I have a 250' beverage as well as a Hi-Z 3 vertical system. To control them I have the RAM-34 XL Preamp System. Both receive systems are connected to the RAM-34 allowing me to switch up to 4 receive antennas and choose filters for 40 through 160 as well as Attenuation for 5 to 20. If you look out on my QRZ page you can see what antennas I have.

Hopefully, this give you an idea of what I have.

Mark KB3Z

KD0RC

Wow, nice setup Mark! With a sophisticated antenna system like that, you could certainly use the 6600 to great advantage. The two SCUs let you have total control of the two receivers. With my 6400, if I am on 20 and want to monitor 6 at the same time, I can only have one RF Gain setting for both slices on the one SCU in the rig. Also, my 3rd order bandpass filters need to be switched out to hear both bands simultaneously (happens automatically and SmartSDR lets you know abut it).

With the 6600, you can have completely independent RF Gain settings on each SCU, and keep your 7th order bandpass filters in play on the contest bands. That 50 dB or better isolation means that SO2R becomes quite practical. Flex has a worksheet to help you understand the limits of power and antenna proximity so that you can safely transmit and receive simultaneously.

From personal field day experience with a couple of 6400s, these radios are very tolerant of big signals with close antennas. The 6600 blows the 6400 away in this regard.

Best of luck with your decision!