[Elecraft] KSYN3A FAQ

[Wayne Burdick]

The KBPF3's lowest-frequency filter has a nominal passband of 0.5-2 MHz. The rolloff is not particularly steep, but this is the reason that the MDS at 250 kHz is -90 dBm, while it's -125 dBm at 450 kHz.

Intermod should rarely be a factor because of the K3's very robust front end.

Those living practically on top of an AM broadcast station typically have been through this drill already and have notch filters. If not, we can design one for you (you get to build it, though :)

Wayne
N6KR


On Feb 13, 2015, at 10:53 AM, Eric NO3M <no3m at no3m.net> wrote:

> What is the passband of the filtering engaged in the KBPF3 when operating at 630M?  The concern at this band in many locations is BCB intermod, and generally an LPF is used in the RX chain.  Is it not of concern based on on-air tests, perhaps KBPF3 is on the table for an upgrade, or an outbound LPF recommended?
> 
> 73 Eric NO3M (experimental 630M license: WG2XJM)
> 
> On 02/13/2015 01:27 PM, Wayne Burdick wrote:
>> 
>> Q:  What is the K3's 100-490 kHz receive sensitivity? What signals would I find in this range?
>> 
>> A:  With preamp OFF, we measured about -125 dBm at 475 kHz and -90 dBm at 250 kHz. We have not measured MDS below 250 kHz, but the receiver will gradually become less sensitive as you go lower in frequency due to band-pass filter rolloff (in the KBPF3, which is required for operation below 160 meters). These tests were made with the signal routed through the RX ANT IN or XVTR IN jacks on the KXV3 option module. The preamp is not effective in this range and must be turned off. A sub receiver (KRX3) fitted with a KBPF3 should have similar performance, whether the signal is obtained from the main path (KXV3) or from the sub's AUX RF input.
>> 
>> 
> 
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