Help with another crusty old unknown amp, VJ Boomer RX-50

[napjerk]

Hi, here's another amp I recently bought in a big box of CB stuff. Can't find much information on it, seems to be from the 70's or 80's.

It's a V-J Boomer RX-50, according to the faceplate, 2 pill amp. Puts out right at 100W on my cheap power meter. Has a label on the side that says do not input more than 8W AM or 18W SSB (so I assume it will do SSB even with no SSB switch).

Any info on this would be greatly appreciated. Sorry for the newbie basic questions.

I have 2 of these model amp, the other one has different transistors in it, but I don't have access to it right now to see which ones it has.

Thanks

 

[Justme]

BLW60C transistors, good fo 45 watts each, minus coupling losses and output transformer losses good for 100 watt clean output.
BLW60C VHF power transistor 5.0 dB, 45 W, 175 MHz, 9.0A, 36 V
Relative clean that is, needs filtering after it to be real clean.
Used them in a long time back for 2 meter and FM commercial band amps.
Good high gain used on 27 MHz, don't overdrive.

Could have bias, looking at the pictures for SSB constant class A/B bias, no problem fo AM/FM, but then not needed just for SSB.
Most of these designs are all copy's of the Motorola handbook which i still have with description of thir line of RF transistors and some designs for RF amplifiers using them.
Made my 160 watt 2 meter Class A/B amp from that design as well, using MRF 247 Class A/B transistors 35 years back.

 

[Justme]

Just adding, looked it up in the Motorola bible, that design was for the 2 x MRF454 80 watt transistors, good for 140 watt output class A/B.
These BLW60 will do a bit less, stick to 100 watts out max preferable 80 to 90 to stay safe.
Here is the Engineers Bulletin i have in my book.
http://www.communication-concepts.com/content/EB63A/Original_EB63_Engineering_Bulletin.pdf

 

[napjerk]

Thanks for the info and the link to the bulletin!

 

[napjerk]

Thanks again Justme, I opened up the other Boomer RX-50. Internals all look the same but the transistors are different. They appear to be of different makes (Sylvania?). What can you tell me about this one vs the one pictured above?

Here's the pic:

 

[Justme]

NTE325
Silicon NPN RF Power Transistor 50W @ 30MHz.
Features:
- Specified 12.5V, 30MHz Characteristics:
Output Power = 50W
Minimum Gain = 11dB
Efficiency = 50%

Other transistors, same design, all run 2 transistors to make about 100 watt, choice of transistors was what was available and cheap....
Code on transistor says it was made in 1991 red dot is for the bias and selecting two with same dot for biassing right.
I build such amp with MRF 454, did nice, add low pass filter behind it.
The MRF 454 had enough headspace, these transistors are on the edge for 100 watt.

Using VHF transistors was a much seen choice, more gain so lower input power needed as with the MRF 454.
But the MRF 454 was specially made for SSB and HF, more rugged and more headspace.
( and more costly as well...)