Bruce,
I've never seen any stud mounted RF transistors with a high output rating,
something like 50-60W at the most. The reason why is the heat dissapation of
the substrate inside. The stud mount gives less cooling area. Anything over
that were flange mounted and had a greater cooling surface. Motorola was the
primary mfg. at one time for a huge number of private labeled RF transistors
like the MRF series, which I wouldn't doubt that those are. That's who private
labeled those for RF Parts.
Best,
Will
*********** REPLY SEPARATOR ***********
On 1/30/06 at 7:08 PM Bruce Brackin wrote:
>Has anyone ever run into one of these big old solid state 6M amps? No
>tubes but would qualify as boatanchor at well over 50 pounds. A former
>owner tried getting 1 kw out. The amp is rated at 1 kw input so you can
>guess what happened. I'm in need of a set of final NPN transistors
>(4). The company is no more and the original finals were stamped with
>their proprietary part number, so finding a cross reference hasn't
>worked. The owner/designer never gave out actual transistor specs, even
>to employees.
>
>The V360 dates from the late 70's and has a big 24v internal supply. It
>runs two identical PA boards with two finals each so the 4 finals take
>20w (max) coming from driver - split 4 ways - then back together with
>stated 1Kw input for PEP or 750w for FM,RTTY,CW,FSK,AM and specs say
>output of 500-600w PEP and 350-450w for FM,RTTY,CW,FSK,AM. It
>apparently took very little drive (<5w). An email from a former
>employee of RF Power Labs said 1-2w of drive would max most and blown
>finals were a very common problem.
>
>The original finals are 0.5" stud mount (10-32 stud) and given amp
>specs, it sounds like a 28v NPN rated at about 5w in and up to ~ 100w
>out cw/fsk or 150w PEP rating at 50 MHz or about 12db gain figure for
>each. Most of the stud mounts I've found are only in the 30-50w range
>and that may also explain some of the blown finals. There may have been
>a poor heat transfer problem right from the start due to the small sink
>area.
>
>I've struck out so far. If push comes to shove, there is the
>possibility of some careful Demerel tool work and adapting to a flange
>mount type. It is otherwise a really well designed and laid out amp and
>a shame so many sit with same problem. The Philips BLW77 (SOT121B
>flange) has been recommended by one person. In addition the Advanced
>Semiconductor HF220-28 or HF100-28 might work at 50 MHz.
>
>Open to suggestions and TNX in advance - Bruce, N5SIX
>_______________________________________________
>Amps mailing list
>Amps@contesting.com
>http://lists.contesting.com/mailman/listinfo/amps
_______________________________________________
Amps mailing list
Amps@contesting.com
http://lists.contesting.com/mailman/listinfo/amps
|