MRF497 CROSS REFERENCE

[W2PFY]

I'm looking for a transistor for my HR 2600 rig. This is a replacement for the final. The specs for the above are attached but I'm hoping there may be a more common replacement for it. RF parts wants $40.00 for it. I can't seem to find any other source for it.


Thanks in advance!

Terry

[WA1GFZ]

RF parts is your best source

[W2PFY]

RF parts is your best source

Isn't there anything else that would work for less money?

[KB2WIG]

40W 50MHz V(ceo): 18V V(cbo): 36V V(ebo): 4V 6A RF power NPN Silicon Transistor

http://www.datasheets.org.uk/MRF497-datasheet.html

The above may help.... check to see whatt may be close fer yer app.My Motorolla data book doesn't have the '497 listed. You may try googeling moto or national semi for application notes......

klc

[KD6VXI]

Ahh yes...  The 100 watt conversion article that netted an honest 50-55 watts.

You can go BACK to the MRF477.  It's MORE expensive.

I've also substituted MRF455s, 455As, 2SC2290s, etc.

If you're a FET guy, their is the EKL2030 MOSFET (a rebadged IRF520) and the EKL 7530 (which is probably more suitable, it's 'rated' for 75 PEP at 10 meters...  I've not figured out which switching fet this is rebadged).

There is also the RFX75 board.  I am NOT a fan of for SSB amplification.  The guys who built it don't own an oscope, I believe.  It's a baseline monster on AM, and SSB looks like a squarewave.  BUT, they are cheaper than the 497.....

FYI, the 477 is a HF xister.  The replacement 497 that the article used is a VHF transistor.  Under the wrong conditions, it CAN break out into oscillation in the 6 meter area...  Judicious use of RC feedback cured that when I was performing the mods in that article.  It takes another 2 caps to get any real increase, but when tuned correctly, a 497'ed 2510 or 2600 will do 80+ pep, it's low level mod, so it does it AM as well.

If you go the EKL device route, keep in mind you'll have to twist two pins:  They are NOT the same pinout.  The EKL / IRF devices are 'drop in bolt in' replacements for the 2SC2166/1969 and 2SC1306/2SC1307 combos.

If you have a decent tetrode or high gain amp chain, the 2510/2600 CAN be made to be a 1.5 watt exciter...  I've actually had people request that.  Yank the final xister and redo a cap and inductor, and you have a qrp rig.

Currently President Electronics is still making the radios, but called the Lincoln.  They have a 2SC2290 as the final output xister.  Keep leads SHORT, and it's ALMOST drop in.

--Shane
KD6VXI

[steve_qix]

They show up on ebay (new) from time to time.  I did a Google search, and found an ebay listing with 5 devices for something like $30.

But, there isn't anything currently listed like that.

[WA1GFZ]

Why spend $100 worth of time trying to save a couple bucks.
You want to fix the reason the transistor failed , then use the right part for the design.

[W2PFY]

Why spend $100 worth of time trying to save a couple bucks.
You want to fix the reason the transistor failed , then use the right part for the design.

No one is trying to save 100 bucks, just trying to find a inexpensive replacement. That does happen from time to time but not in this case. What's wrong with trying to find a less expensive alternative?  Looks like there is no such thing. The problem is the final. I'll have to wait till one comes up on eBay.

Thanks for all the help guys!

[N4LTA]

Lots may be wrong with that approach.  The MRF 492 and 497 are tweener bipolar devices  that work at 50 Mhz. Most of the 2-30 MHZ MRF devices have less gain and the ones for high bands have too much.  I used the MRF492 in my 6 meter amp (QST Oct 1990) and have also used the 497 in transverters. There are almost no substitute devices that will drop in and substitute for the 492 and 497. Toshibaba made a MRF492 replacement that almost matched the MRF492. I have never found one for the 497.

If you try to sub with something with less gain you will spend lots of money for nothing and then have to pay for the right replacement.

[WA1GFZ]

correct a mundo
Bipolar amps are designed around a device. They are critical for input Z  and feedback.
Transplants are usually a pita.
FETs are much easier to transplant.

[W2PFY]

If you try to sub with something with less gain you will spend lots of money for nothing and then have to pay for the right replacement.

Well I was shocked about the price for a new one! I was thinking there was something out there for 2 bucks but I'm living in the past!

[N4LTA]

I used to pay about $9 for the 497 and $17 for the 492. They are near obsolete (if not already) and hard to find.

The FETs are the way to go now.  I'll look and see if I still have a 497

Pat

[WA1GFZ]

I tried to modify a MRF429 class B MRI amp to AB broadband. I found that the base trace was about 1/2 inch short so the Base was just a tad short on input l to get a BB match. I wasted a lot of time and never got it right.
OTOH when I switched to MRF150  FETs I was able to do the conversion in a couple hours.
So I am trying to save you a lot of time an head banging.
Trust me $40 will feel cheap.

[N4LTA]

I found two 492s and no 497s in my stash. Sorry - they will be hard to find and not worth the price.

Pat

[WA1GFZ]

I've had very good luck dealing with RF Parts

[W2PFY]

I found a guy in China selling these for $2.50 each. I ordered five.  He has zero feedback so I hope I don't get burned!

http://www.ebay.com/itm/MRF497-TO-220-MOT-/110771923358?pt=LH_DefaultDomain_0&hash=item19ca85699e

He says he has more than ten so if anyone out there needs some, this may be the time to buy.

One of his references on his web site:  Dear Davis!
My plumber checked the transistors and said that all is well.
I can now give full feedback. I am completely satisfied with ..........Or how can I go wrong?

[WA1GFZ]

good luck

[W2PFY]

Thanks, I probably won't see them till December. I have ordered small stuff from China and was surprised at the fast delivery. What was more surprising is the fact that they can send something to me with really cheap postage and if I were to send that same item back, it would cost three times as much.

[Jim KF2SY]

Probably counterfeit parts.

[The Slab Bacon]

One of his references on his web site:  Dear Davis!
My plumber checked the transistors and said that all is well.

Geeze, you got to pick the right guy for the job. (or is something lost in translation)
That would be like going to a Proctologist to get a tooth filled   

He might be able to do it, but I'm sure it would leave a crappy taste in your mouth   

[N4LTA]

May not be counterfeit.

I have a small company in China that will look for parts that I need and the prices are good even with shipping. I have been pleasantly surprised. I got class E FETs and opto osolators that are both fine.

[W2PFY]

May not be counterfeit.

Well this guy is just new to eBay but has a business outside of eBay.

The transmitter was build in the Philippines and the transistors were probably built in one of those countries over there so, I am not surprised that a Chinese surplus seller could find these and post them for sale.

Yesterday I went through all my old positive posts that people have left for me. I was astonished by the number of people who are no longer registered as buyers or sellers. I think eBay will die one day when a better auction house comes along. Just on my list there were 20 percent that are now gone.