Yes Ok Gary, I guessed it was so. I just wondered whther you had a "tight"
filter. The signal out of the chip (do be carefull here) should be a logic
level ..i.e. 5v p-p I would have thought (??)
Cheers de Alan G3NYK
----- Original Message -----
From: "G4WGT - Gary" <[email protected]>
To: <[email protected]>
Sent: 03 February 2004 20:01
Subject: LF: RE: Re: Re: G0MRF 300w Tx & DDS VFO
Hi Alan & LF,
Thanks for the advise, but I did realise that the input is x2 ie. 274 Khz,
it's just that when testing the DDS VFO with the scope on the bench I did
the checks at those freq's mentioned. It is still no different at 274 Khz,
in fact at its best (15Mhz) it is only producing 300mV P-P & not the
expected 1V P-P.
The sig comes out of the DDS IC thro' a 2 pole LPF to a buffer amp IC, the
sig is even lower at the unbuffered output(before the IC). I will have to
remove it from its case to trace back thro' the components.
I will keep you posted
73
Gary - G4WGT
-----Original Message-----
From: [email protected]
[mailto:[email protected]]On Behalf Of Alan Melia
Sent: 02 February 2004 22:12
To: [email protected]
Subject: LF: Re: Re: G0MRF 300w Tx & DDS VFO
Hi Gary Ah you need 274kHz for the feed to the EXT pin it goes to the
input
of a divide by two to give square wave drive to the PA stage. Still you
should be getting more than that out of it. It sounds as though something
is
not right...50mV is far too low. Is there a LPF on the output?? It may be
that there is a component problem there.
Cheers de Alan G3NYK
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