I picked up 2 amps today. What can you tell me about them?

[Turbo T]

I picked up two amps today, both mobile 12 VDC amps.

The first is a Maco Mite II. Inside it has two transistors, both read 185 MACO TR8 636 on them. I searched the web for both this model amp and the transistors and have found virtually nothing.

The second is a Palomar 225. Inside it has two Motorla MRF 455 transistors in it. From what I found, they're good for 60 watts of power each, according to here:

http://www.datasheetcatalog.org/datasheet/motorola/MRF455.pdf

Anyone know if that's PEP 60 watts each or RMS?

And does anyone have any info on the Maco Mite II?

Thanks in advance.

 

[TonyV225]

you should see 160 - 180 watts out of the Palomar 225

 

[Turbo T]

Thanks. How many watts can I expect to see from the Maco Mite II?

 

[eagle1911]

The datasheet power ratings for the MRF455 are peak ratings, so PEP. The MRF455 isn't specified for SSB usage (they're specified as class C transistors, but work fine in class AB applications) but datasheet maximum power ratings are always peak ratings unless labeled otherwise.

 

[AudioShockwav]

Looks like they used a few different Part numbers, but here is some info on the same amp to give you a general Idea.....
Can you post a picture of the inside of the Amp in question?

http://www.worldwidedx.com/tech-repair/24343-need-info-transistor.html

73
Jeff

 

[Turbo T]

The datasheet power ratings for the MRF455 are peak ratings, so PEP. The MRF455 isn't specified for SSB usage (they're specified as class C transistors, but work fine in class AB applications) but datasheet maximum power ratings are always peak ratings unless labeled otherwise.

Thanks...and PEP is usually like what, double of RMS?

Also for what it's worth, the Maco Mite II has an SSB toggle switch on it. The Palomar 225 (the one with the 455's in it) doesn't but from what I've read it supposedly has an automatic SSB in it.

Looks like they used a few different Part numbers, but here is some info on the same amp to give you a general Idea.....
Can you post a picture of the inside of the Amp in question?

Here's a few pics of the inside of the Maco Mite II...

 

[Turbo T]

I don't know how accurate my Radio Shack SWR/power meter is, but after setting the Midland 77-155 down to a 2 watt dead key/8 watt swing, it was showing I was dead keying at around 50 watts and swinging over 200.

Although I find that hard to believe. I still can't find much info on the Maco Mite II. But at least my wife says it makes the door bell buzz when I key up.

 

[eagle1911]

That Maco Mite is an interesting design.. The transistors are the larger sized ceramic package, so they may be able to make close to 200W when driven hard. They could also have very high gain, and require less drive than other types of transistors.

 

[TonyV225]

If your talking about the 2000 watt meter then those meters are pretty accurate I have a few of those and use them allover the bands and their pretty damn close to being spot on if they are off at all. Ive ran these against other meters and compared with excellent results. As I said this was tested on several amateur bands aswell. These are a (Average) meter with (Peak) being for meter movement for SSB readings.

 

[AudioShockwav]

I dug around everywhere I could think of to find info on that transistor...nothing.
I know that Maco had enough business going at one time they even had General Electric make a custom run of tube`s built just for them.
Makes one wonder if they also had some transistors hand picked and stamped with there own Part number on them.
Examples are The SRF 3800, RF Parts hand selected MRF 492`s, or
The SRF 3749, also RF parts brand , hand selected MRF 454`s
Thank you for posting the pictures, as said, very interesting.
Old solid state Maco pictures are rare.
Nice little piece of history there

73
Jeff

 

[AudioShockwav]

To show some of the rare stuff that Brewer labs built back when, I up-dated, and brought back another post about a solid state Amp they built.
The Varmint SSL 600.
It can be seen below.

73
Jeff

 

[Turbo T]

If your talking about the 2000 watt meter then those meters are pretty accurate.

It was one of these:

Part # 21-534. I used the highest scale reading when i did the check. (the middle scale only reads to 200 and it was exceeding that)

I dug around everywhere I could think of to find info on that transistor...nothing. Thank you for posting the pictures, as said, very interesting. Old solid state Maco pictures are rare. Nice little piece of history there.

Thanks. Yes something is telling me I oughta hold onto this little Maco.