Lack of 135 to 165 MHz RX on 6500

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  • Updated 6 years ago
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I am guessing that the 6700 uses passband filtering and harmonic subsampling to receive 135 to 165 MHz. Why doesn't the 6500 use the same technique? Lack of room for filters? No room in FPGA? Product feature differentiation?

Also is the 135 to 165 MHz RX available on both SCUs of the 6700? Which ant ports can you use?
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Tim K8XS

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Posted 6 years ago

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Greg - K5GJ, Elmer

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Official Response

Your post actually has most of the answers in it:

1. The FLEX-6700 and FLEX-6700R are the only radios in the FLEX-6000 family that support the 135MHz to 165MHz band for receive/low level transmit.

2. On the FLEX-6700, we accomplish the VHF band by using a combination of:
a. Sampling above the critical Nyquist frequency.
b. A much larger and faster Field Programmable Gate Array for processing
c. A faster System Processor for processing
d. Dual Stage Pre-amps to make up for the loss associated with this sampling technique.
e. A complex anti-aliasing/bandpass filter to block FM Broadcast signals from overload but allow the VHF signals to pass. Note that on the FLEX-6500, a 70MHz anti-aliasing filter is inline always so no VHF signals will ever make it to the SCU A/D converters..

3. Yes both SCUs on the FLEX-6700 have the capability to receive VHF. Also, the Direct UpConverting (DUC) exciter is configured and filtered to allow for low level VHF transmission of up to +5dBm output power in the 144-148MHz range.

4. Lastly, YES, there is distinct product differentiation between the FLEX-6700 and FLEX-6500 products. The FLEX-6700 was designed as a "NO HOLES BARRED" Best in Class transceiver where we spared no expense to get the top performance. The FLEX-6500 provides much of the same world class performance with a slimmed down feature set to address a specific market point. Because of the additional costs involved, VHF was not included in the FLEX-6500.

I hope this information clears up any confusion.

Greg - K5GJ