*My Omni D will do QRP also. No Mods that we know of.*
* 73 from Wade/KJ4WS*
On Fri, Nov 14, 2014 at 1:49 PM, Neil Martinsen-Burrell <
neilmartinsenburrell@gmail.com> wrote:
> As a follow-up on my message from earlier this week, I hooked my Omni B up
> to a dummy load and measured the power out using a DVM and a diode
> detector. Besides verifying that the max power was around 104 watts on
> both 40m and 80m, I was able to turn the power down essentially as low as I
> wanted just by turning down the DRIVE knob. I was able to get down
> reliably to around 3V peak (approx. 1 watt). It did not take much turning
> of the knob to get down to sqrt(5)*10 = 22.4 volts (approx. 5 watts).
>
> I mistakenly trusted the manual which specified that the DRIVE knob will
> only turn the power down to 25 watts. That does not appear to be the case
> on my Omni B. It is possible that my radio is mis-adjusted or already
> modified in some way, but I think that is unlikely as the radio has been
> serviced at the factory a few times in its life already.
>
> I didn't hear any of the 80 meter foxes on my low dipole, but I was ready
> with just 5 watts to call them back!
>
> -Neil KD0UKC
>
> On Tue, Nov 11, 2014 at 4:05 PM, Neil Martinsen-Burrell <
> neilmartinsenburrell@gmail.com> wrote:
>
> > With the upcoming QRP Fox Hunt season (one of my favorite weekly
> operating
> > opportunities) I am interested in the possibility of using my main
> station
> > rig at QRP power levels. My QRP radio is an HB-1A with RIT that does NOT
> > remember the offset settings when RIT is switched off and then on. This
> > means that it take a lot of fiddling to listen to a split pile-up to find
> > the station currently being worked. I would prefer to use the Omni with
> > its separate offset knob and a RIT on/off switch so that I could easily
> > switch between the offset and non-offset frequencies.
> >
> > There are google mutterings from the late 1990s in this list's archives
> > about a mod that might change the range of the ALC knob from 0-20 instead
> > of 25-100 watts. Does anyone know if such a mod exists as more than a
> > rumor? On my previous Kenwood TS-520SE, there was an external ALC pin
> that
> > could be driven with a negative voltage to reduce output power. Is there
> > something similarly simple for the Omni 546B?
> >
> > I can see from the schematic that R21 on the 80743 low level driver
> > controls the effect of the ALC control pot, but it seems like that isn't
> an
> > easy solution to getting down to QRP power levels, at least without some
> > fiddling to figure out what value would give the appropriate minimum and
> > maximum power levels.
> >
> > Thanks in advance for any help you can offer.
> >
> > -Neil KD0UKC
> >
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