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

The fact that the obnoxious grumpy neighbor across the street from me still has over the air TV with a 25 year old corroded TV antenna, a crappy TV amplifier all hooked up with deteriorating 300 ohm open wire line and I love to operate 6 meters at 300 watts output.

Ditto that anything can be made to radiate, the question is if your stressing your HT's output device.

As an example; Time frame 1975: A 100 watt light bulb on the output of a Tempo One transceiver, Band: 15 meters. Results: A successful qso with a ham 5 miles away in the neighboring town.

 The question is what's the forward and reflected power on your antenna.

 Not knowing these new radios I don't know how rugged the output device's are on any of them.

 Another good check to go along with a FWD/REF RF power meter would be an external power supply on the Chinese HT with a DC current meter to see what the Power amp efficiency is with your makeshift antenna.

Your lucky you only have one at 50.125 MHz How about a list of products that cause birdies on all of my 6 meter radios from 50.000 to over 53 Mhz.

1.Black and Decker coffee maker.  Fixed by wrapping cord with ferrite chokes.
2.Netgear Router.  Fix: Replaced wall wart power supply with a home brew linear regulator.
3.CFL lamps.  Fix: tossed all CFL's out and purchased a good supply of incandescent bulbs.
4.Cable TV leakage.  Fix: Removed all of the unconnected cutoff cables handging off of the entry panel and terminated all of the connected but unused ones.
5.Electric lawn mower pulse charger.  Fix: a nice old gas mower as a replacement works wonders.
6.Electric Leaf blower charger, (The green people can toss their electric gas replacements in the garbage as far as I'm concerned)  Fix: used the internal battery for another project and I smashed and tossed the electric leaf blower in the garbage. I can honestly say that it was an exhilerating feeling smashing this junk device with a sledge hammer.
7.Neighbors plasma TV. Fix: 6 meter band modified MFJ 1026 nulling box. This device worked so well that I can now hear and work Europe on a small 5 element yagi during those rare band openings.
8.Street light a half block away with faulty photocell that local Power company hasn't fixed yet.  Fix: keep bugging portland electric to fix this wonderfully designed piece of art ( sarcasim).




good luck with your noise

Mike

If you can stand MFJ now owning Hy-gain then these may work for you>

http://www.hy-gain.com/Product.php?productid=DB-1217


http://www.hy-gain.com/Product.php?productid=LJ-204BA


The first is a 3 element dual band antenna built as either a 10/15 meter or 17/12 meter antenna at the time of build but it may be the closest antenna to your specs at an ok price.

The second one is only a single band antenna but it's a 4 element design built as either 17 or 20 M so it may also meet your budget.


 

The Marconi 2019 has a one touch frequency increment feature that is standard.

  If you hold the up or down frequency key in then the frequency will automatically step up or down in a preset increment then wait one second on frequency and repeat incrementing or decrementing until it reaches a preset maximum or minimum frequency after which it will then roll back to a pre programmed lower or higher frequency.

There is also a method to eliminate the 1 second hold time on a stepped frequency but since I don't have that model gen anymore I don't remember the exact method to set it up.

These features should be in the 2019 manual on how to set the min and max frequencies and the increment step and how to make the generator perform a pseudo sweep.


Mike

They may be legal accorrding to Industry canada regs:

Interesting as I didn't know this rule existed direct from Industry Canada web page.

From industry Canada's Amateur radio regulations section 42:

http://laws-lois.justice.gc.ca/eng/regulations/SOR-96-484/page-10.html#h-41

Operation in the Amateur Radio Service
Operating Qualifications

42. An individual may operate radio apparatus in the amateur radio service if the individual is the holder of one or more of the following certificates or licences:

(a) an Amateur Radio Operator Certificate with Basic Qualification;

(b) a Radiocommunication Operator General Certificate (Maritime);

(c) a Radio Operator’s First Class Certificate;

(d) a Radio Operator’s Second Class Certificate;

(e) a Radiotelephone Operator’s General Certificate (Aeronautical);

(f) a Radiotelephone Operator’s General Certificate (Maritime);

(g) a Radiotelephone Operator’s General Certificate (Land);

(h) a First-Class Radioelectronic Certificate;

(i) a radio licence in the amateur radio service and an amateur radio operator authorization, issued by the responsible administration of a country other than Canada, if

(i) the individual is a citizen of that country, and

(ii) a reciprocal arrangement that allows similar privileges to Canadians exists between that other country and Canada; and

(j) a radio licence for a radio station in the amateur radio service issued to a citizen of the United States by the Government of the United States.

Section (e) may grant them the authoization to operate but only if they have a valid General Aeronautical certificate.


Mike