You haven't mentioned if the VX7R receives the repeaters when manually tuned to your local repeaters, you  only mention that when scanning it doesn't pick them up.

 Also have you confirmed that Commander programmed the frequencies correctly?

 I know that with some radios if the frequency step is not set correctly to begin with then the final channel programming will be off, I have this issue with an icom T7H and an Alinco radio.

After all you are relying on a Microsoft Windows PC to set the frequencies of your 300 dollar radio and we all know that Microcrap never screws up nor does the software written for it ever screw up.

I don't see anything on MaComs web page about them going away either

Or find a girl who's father and 3 uncles are hams and they always took her to various field day outings for more than 15 years when she was growing up.

After those kind of memories a 40 foot tower, a couple of masts for the wire antennas and a HF/6 meter radio running all the time in the background is nothing to her.

That's good to know about the pickit3 problems.

 I guess if the 2 isn't broke, especially in this crappy economy, then there's no sense in replacing it.

I 2nd the microchip pickit 2, the best and easiest programmer I have ever used.

If you use an ICSP header on your project then you can simply connect the pickit 2 to your header and program away.

http://www.microchipdirect.com/ProductSearch.aspx?Keywords=DV164121

It really is a fair price but I still want to try the new pickit 3 to see what more it offers.

 Ouch 330 dollars,

 The MFJ's are pricey, the AEA's are pricey, the Autex is overpriced, even the little You kits analyzer is pricey they are all overpriced.

 I can't believe I'm saying this but I sure wish a Chinese Co. would come out with a good antenna analyzer with smith chart display and all the other features that the others on the market have.

 I'd figure it would cost them around 20 dollars in parts and it would sell for around 50 to 75 dollars, if they can make a 50 dollar dual band Ht then an antenna analyzer shouldn't be to hard to manufacturer for a similar price.

 Again I can't believe I am even suggesting this, but this crappy economy is really turning me into a cheap skate.

That's the only reason that I made such a comment because in two QTHs that I have lived at the locals wouldn't embrace anything new and it was impossible to get em off their butts to try anything out.

 I was loaning out 900 radios and they never received any use, I had the repeater with a high location and a fair amount of power into a commercial 10 dB gain omni plus a 6 meter remote base which was frequency agile.

  There were lots of 6 meter sparodic E openings on the Remote base side and I would even announce the openings on another band but still nobody ever got on the 900 MHz side so I tore it all down never planning to put it back on the air.



Mike

About the only thing he can do now is to disconnect the bad transistor side from the wilkinsons and run at reduced drive to just see if the other transistor is good.

 This is better than replacing both transistors without knowing if both are damaged.

 Also the SRF3883 is the correct transistors for that model amp but I don't think that RF parts has them anymore as I remember the SRF parts were tighter beat matched parts and they were made exclusively for a particular manufacturer.

  As is mentioned above the difference between the SRF3883 and the MRF247 was different beta and also tighter beta matching of the SRF3883 parts but even with the wilkinson splitter/ combiners being used the tight beta matching shouldn't be a major problem if he uses RF parts Co. MRF247 or similar replacement.

About the only thing he would need to do is set Idq for any replacement transistors, I can mesasure my amps Idq if he needs to know how to set bias which he probably will.

 

I have that exact same amplifier sitting in front of me and the overheated/problem component is not apparent because the schematic posted is not the same as your amplifier.

 My amplifier went thru a feed back modification to fix some spurious issues and it now looks exactly like yours does, originally it had a single molded choke as L9 and L10.

 These amps went thru an ECO, (Engineering change) at some time in their design cycle with changes made to the collector to base feedback circuitry, what is shown as L9 and L10 in the schematic was changed from a single molded .15 uh choke to a small wirewound choke in series with a VK200/Fb  multi hole bead choke.

The small wirewound choke is encapsulated in an almost clear shrink wrap and in the right transistor it sure looks like it is blackened near the transistors inner flange mounting screw at the junction with the multi turn bead.

It looks like the junction of the wirewound choke and the VK200 ferrite bead choke actually arced to the flange mounting screw.

Someone probably modified this amplifier with the spurious feedback fix and didn't properly dress/insulate the leads at the junction of the changes and or over drove the amp causing the feedback network to unsolder and possibly drop down and arc to the flange mounting screw.

The amplifier uses a wilkinson combiner on the input and output so its easy to disconnect the right side amplifier by removing the lower transistor but I would also open up the feed back choke where it is burnt by unsoldering at the junction of the multi hole bead and the burnt inductor under the clear shrink tubing.

I would also remove the UNELCO metal mica capacitor on the base side of the bad transistor because it looks black and possibly shorted along with removing L7 which feeds bias to the base of the suspected bad transistor, this should totally isolate the suspected bad transistor side.

next try driving it with half power or less, around 20 to 25 watts, only because the input wilkinson resistor will start to dissipate the power on the open transistor side and it will get hot during these tests.

 Unfortunately I don't have a good updated schematic of what the amp looks like with these feedback mods but this should get you started.

 Also the fact that one side is damaged there is the possibilty that someone drove it over the max drive level and damaged both transistors but still by disconnecting the lower device this will be obvious if you don't get any power out with the top amp chain connected up

Mike

If your into guns and radios then I can see a use for 900 MHz radios.

 If only there was a skeet launcher that could throw a 900 Mhz maxtrac or a vertex repeater 300 feet in the air, I would open up a shooting range.

Mike

Or you could make a real 6 meter antenna, anything is better than this antenna on 6 meters.

I had a friend who had that antenna and it never tuned up on 6 meters, it was extremely narrow banded and even when tuned it didn't radiate well nor did it stay tuned on 6 meters.

 It was a constant struggle trying to make that antenna work.

It's probably better than my new Dell desktop or my new Dell laptop but even a good old Tmex Sinclair would beat any Dell anyday.

 I agree about the package being inconvenient to prototype with.

 Working on commercial Avionics RF Power amp design for the past 22 years I have come to the realization that you either pay the higher price for a real ceramic flange mount device or go the lower cost route designing with a plastic pack surface mount device that requires 50 or more backside ground vias and a more careful thermal layout.

 I'm now designing avionics pulse amps and stuck with using 250 watt mode S surface mount devices when my gut feeling and past experience has been to stick with the ceramic flange mounts.

From a replacement/servicing standpoint the flange mount part that I want to use is much more easy to remove wheras replacing the surface mount part, which has 50 vias soldered to the devices backside pad,  usually results in a damaged PCB after even one part replacement.


 I have found that these days most if not all manufacturers want to sell the cheaper plastic SM devices as opposed to supplying the more expensive, easily replaced, leaded ceramic devices.


 Good luck with whatever part you choose.


Mike

Since you didn't specify a newer model radio I would have to say a Yaesu FT-90 would fit the specs but only if you could find one on the used market because it isn't in production anymore.

 But watch out for extended high power, 50 watt operation.

MRF6V2010 from freescale is single ended but it may work.
http://www.freescale.com/files/rf_if/doc/data_sheet/MRF6V2010N.pdf

around 27 dollars at digikey
http://www.digikey.com/product-detail/en/MRF6V2010NBR1/MRF6V2010NBR1CT-ND/3524239