On Wed, Jul 28, 2004 at 10:23:15AM -0400, Rick Stoneking wrote:
> Has anyone done the modifications listed on the FT-736 2m Power amplifier
> schematic that changes the output to 10W? We are converting a 736 to be a
> UHF station (222, 432, 902, 1296) and are using a transverter for 902 to
> 2m. The transverter has a 10W input max, so we would like to permanently
> set the 2m output to 10W so that we do not have to worry about adjusting
> output power when changing bands. Hoping to get confirmation that the
> changes listed on the schematic work okay.
The power output can be set for each band in
the FT-736 - I have done it to one for the 222 Mhz band.
>From the informaion I have:
---------------------------------------------------------
"From a previous post"
I think the adjustment on the 736R you were thinking of is the AFP or
Automatic Final Protection circuit. I've always thought this was a little to
sensitive. Here's the alignment procedure to check how the circuit is set.
Remove the top cover taking care not to break the speaker lead.
There are two circuit boards that we want to check. The board in the middle
is the 2M board, and the one on the right is the 70cm board. If you look near
the rear end of both boards, you will see a small vertical circuit board.
Right near these are three potentiometers. Let's start with the 2M board.
The pots are located behind the small vertical circuit board. The pots are
labels VR02, VR03 and VR04 left to right. First we must connect a dummy load
and wattmeter and verify that we have 25w RF with the front panel drive
control set to MAX. Set the radio to FM and set the freq. to the center of 2M
band. Press MOX and adjust VR02 (the left pot) for 25w. Next check the front
panel meter for an indication of 8 on the PO scale. If not, adjust VR04 (the
right pot) for the correct meter indication. Now for the AFP.
Connect a DC voltmeter to the anode of D32. This diode is in front of the
little vertical circuit board towards the left side. With the radio
transmitting, adjust VR03 (the middle pot) for 1.0 volts. That's it for the
2M side.
On 70 cm, the pots are labeled VR04, VR05 and VR06. They are located in front
of the small vertical circuit board. The same drill here for Power out. Set
freq to the middle of the 70 cm band and adjust VR04 (the left pot) for 25
watts and VR06 (the right pot) for 8 on the PO meter. The AFP meter point is
alittle different. Connect your DC meter to Jumper A which is located just to
the left and slightly behind VR04. The jumper orientation is front to rear,
as opposed to a left to right jumper that is located behind the pots. As
before, with the radio transmitting, set VR05 (the middle pot) to 1.0 volt.
That's it for the 70 cm board.
-------------------------------------------------------------
I also have the 222 instructions here somewhere.
--
George Fremin III - K5TR
geoiii@kkn.net
http://www.kkn.net/~k5tr
_______________________________________________
VHFcontesting mailing list
VHFcontesting@contesting.com
http://lists.contesting.com/mailman/listinfo/vhfcontesting
|