[NLRS] Setup of DEM TIB/222-28 + IC-706MkIIg

[Brent Casavant]

On Wed, 4 Jun 2003, John P. Toscano wrote:

> Brent Casavant wrote:
>
> > The 222-28 manual
> > said that at full output power I should expect to see about 6W of draw
>
> I'm guessing you mean 6 AMPS, not 6 WATTS. . .

Oops. You're right.  Too much typing and not enough proofreading.

> I'm worried about the RF power meter showing 15 watts on SSB with no
> audio into the microphone.  I wonder if you have an oscillation that is
> driving the transmitter fully even when you aren't talking into the mic.

This morning I tried again for a few moments before going to work.
The only difference between last night and today was that last night
I had the antenna outdoors, and today it was indoors a few feet away
(RF safety being blatantly ignored).

Anyway, I only tried FM (on 223.5) and this time I got 0 watts of output
from the transverter.  It wasn't until I was driving in to work that I
remembered I may have turned the ALC down to -4.0 volts right before
bed last night, so I'll have to try it again when I get home.

>   And if you have an excess of ALC voltage, even in FM mode, the RF
> output should be much less than 15 watts.  Maybe your VHF wattmeter is
> not working properly at all?????

Oh, the 15 watts was another goof.  I was reading the 300W scale on
the meter instead of the 30W scale.  I believe it was actually 1.5W
I was seeing last night.  Sorry.

> Anyway, once I had the radio throttled down to something that looked
> like it was at least in the neighborhood of 200 mW, I hooked up the
> transverter, moved the dummy load to its output, and tested.  I could
> feed more (negative) voltage into the ALC line and drop the 222 MHz
> output from full drive (close to 25 watts) down to 1 watt (or less!).
> In other words, once I got the ALC in the proper ballpark, I adjusted it
> with the 222 MHz output level instead of the 28 MHz output level.  Since
> you probably want maximum power out, you could provide enough negative
> ALC voltage to see a clear drop in 222 MHz RF power below 25 watts, and
> then very gently reduce the ALC drive (bring it closer to zero volts)
> until the 222 MHz RF output stops climbing, which should be at about 25
> watts.

This is essentially what I was trying to do, but starting a little more
blind on the ALC/IF drive than you did as I don't have a sensitive
enough HF wattmeter.

One thing that did concern me is that the TXIF pot in the transverter
would cause a 0W RF output unless turned fully clockwise, where the
RF output would jump to the maximum I could manage to get it to go.

> And all these tests were done with the 706 in FM mode so I would get a
> full-power 100% carrier whenever the PTT was activated.  After getting
> it set up on FM, I switched to the other modes and verified that
> everything was still being driven to the proper levels in CW or SSB.

It's good to know that the 706 will obey the ALC on FM.  Something
in the transverter manual made me think that some rigs only obey
the ALC on CW.

Thanks for your help.  I'll continue looking into the problem tonight.

Brent

-- 
Brent Casavant            http://www.angeltread.org/
44.9067N 93.0558N 907F    -.- -.. ..... . -- -...