[Elecraft] OT: QST's review of the Yaesu FTDX5000MP

[Joe Subich, W4TV]

> Hmm, item 4 about the synth not going above 33MHz does not make any
> sense. With a 1st IF of 73MHz for the up-conversion path, the LO
> would have to be 103MHz just to reach 30MHz and 127MHz to get to
> 54MHz.

The "up conversion" receiver uses a completely different synthesizer
(and different synthesizer design).  In fact, the "up conversion"
receiver is essentially an entirely separate receiver from the
antenna (T/R switch) to the DSP unit.

73,

    ... Joe, W4TV


On 11/15/2010 5:48 PM, ab2tc wrote:
>
> Hmm, item 4 about the synth not going above 33MHz does not make any sense.
> With a 1st IF of 73MHz for the up-conversion path, the LO would have to be
> 103MHz just to reach 30MHz and 127MHz to get to 54MHz.
>
> AB2TC - Knut
>
>
> Joe Subich, W4TV-4 wrote:
>>
>>
>>>> That makes absolutely no sense to me. Can you or anyone else here
>>>> well versed in radio design please explain to me why the Kenwood
>>>> engineers would do this?
>>
>> The best guess is that Kenwood did not want to invest in 1) the high
>> performance front end (bandpass) filters for the non-amateur bands,
>> 2) quality 6 KHz and 15 KHz (low frequency) IF filters, 3) give up
>> coverage +/- 500 KHz of the "first" IF, and 4) their unlocked DDS
>> synthesizer would not work above 33 MHZ (limiting down conversion
>> to a maximum frequency of 22 MHz).
>>
>> Very bad design with slick marketing.
>>
>> 73,
>>
>>      ... Joe, W4TV
>>
>> <snip>
>>
>