Here's my first moment's impression of the DEMI 432-28HP Transverter with a mod for the FM Repeater end of the 70 cm band:

The Amplifier is listed as 50 watts nominal. The instructions suggested driving it at a level when all but the last power LED was lit. My Power meter is a Comet CMX2300 (someday when Larry Phipps finally gets finished tweaking his LP-500 design, I will be using that for such measurements).

At first I set my transverter to 450.000MHz and tweaked the XVTR's Max Power to -5.3 dBm, where all but one power LED was lit). Here is the frequency vs. power approximately:

440MHz <1 Watts

441MHZ 3Watts

442MHz 4 Watts

443MHz 6 Watts

444MHz 9 Watts

445MHz 11 Watts

446MHz 15 Watts

447MHz 21 Watts

448MHz 25 Watts

449MHz 28 Watts

450MHz 32 Watts

If you change the Max Power setting to its highest one (15.0dBm) you can squeeze out 10 watts at 440MHz - the higher frequencies are also driven to higher output power, but eventually you will overdrive the amplifier into distortion and see >40 watts output.

The pre-amplifier gain is much better in this model than DEMI's first attempt and I did not feel the need to slap on any further pre-amp gain thru the Flex6700.

The best game plan, as I now see it, is to place the Max gain much higher than -5.3dBm and "ride the gain with the RF Power control of the 6700 (this should be easier when/if I get a LP-500.

It seems like the folks at DEMI designed the filters to peak just at the 450MHz point - I would have chosen something more like 445MHz since Repeater transmit frequencies are equally scattered over the 440-450MHz range....

Well, it just came in a little bit longer than an hour ago, but I'm a "happy camper". Is it "perfect? What is? But you'll do, little 432-28HP, you'll do...

Any questions? (Keep in mind that my test equipment is presently close to non-existent.)

Ain't technology fun!!!

73,

Roy, AC2GS

The Amplifier is listed as 50 watts nominal. The instructions suggested driving it at a level when all but the last power LED was lit. My Power meter is a Comet CMX2300 (someday when Larry Phipps finally gets finished tweaking his LP-500 design, I will be using that for such measurements).

At first I set my transverter to 450.000MHz and tweaked the XVTR's Max Power to -5.3 dBm, where all but one power LED was lit). Here is the frequency vs. power approximately:

440MHz <1 Watts

441MHZ 3Watts

442MHz 4 Watts

443MHz 6 Watts

444MHz 9 Watts

445MHz 11 Watts

446MHz 15 Watts

447MHz 21 Watts

448MHz 25 Watts

449MHz 28 Watts

450MHz 32 Watts

If you change the Max Power setting to its highest one (15.0dBm) you can squeeze out 10 watts at 440MHz - the higher frequencies are also driven to higher output power, but eventually you will overdrive the amplifier into distortion and see >40 watts output.

The pre-amplifier gain is much better in this model than DEMI's first attempt and I did not feel the need to slap on any further pre-amp gain thru the Flex6700.

The best game plan, as I now see it, is to place the Max gain much higher than -5.3dBm and "ride the gain with the RF Power control of the 6700 (this should be easier when/if I get a LP-500.

It seems like the folks at DEMI designed the filters to peak just at the 450MHz point - I would have chosen something more like 445MHz since Repeater transmit frequencies are equally scattered over the 440-450MHz range....

Well, it just came in a little bit longer than an hour ago, but I'm a "happy camper". Is it "perfect? What is? But you'll do, little 432-28HP, you'll do...

Any questions? (Keep in mind that my test equipment is presently close to non-existent.)

Ain't technology fun!!!

73,

Roy, AC2GS

Mike

Roy Laufer

I plan to "play" with the transverter before deciding if an amp is necessary - I may get by with just riding the gain a bit...

Roy Laufer