Stuart Longland VK4MSL wrote:
On Apr 25, 2:30Â*am, GW1CJJ wrote:
My FT=290 is slightly off frequency on TX, it is about 4Khz lower than
the display frequency but the RX is spot on display frequency so I have
to operate with the clarifier switched on to be able to resolve the
other station. Antone know how I can adjust this??
Cheers

I've got a MkII here with a similar problem, although it's not as
severe... about 600~800Hz off from the actual frequency. I'm guessing
it could be the age of the reference crystals having an impact (these
are frequency synthesised rigs), but without ripping the thing apart,
I'm not sure.

1kHz isn't enough to bother me... just use the frequency display as a
guide then tune around until you get the target station spot on. 4kHz
on the other hand, would be quite irritating.

I have the original FT-290 (I presume that is what he refers to when
writing Mk1, but I am not sure).

In this rig, the synthesizer is running at a constant frequency offset
from the tx/rx frequency by the first IF. The transmitter operates by
generating FM/SSB/CW at the first IF and mixing it with the synthesizer
frequency.

As SSB is generated by modulating a crystal frequency using a balanced
modulator and then feeding it through the IF filter, I think that if this
crystal is off frequency there will be a severe effect on the modulation
(as the filter passes the wrong part of the spectrum).

That is why I asked if modulation is affected. If it isn't, it is a bit
unclear where the frequency difference between rx and tx can originate.

(of course, it is easy to explain a difference between actual rx AND tx
frequency and the dial display)

It could well be that the MkII has a different method of operation.