Home
JAQForum Ver 24.01
Log In or Join  
Active Topics
Local Time 04:12 10 Nov 2025 Privacy Policy
Jump to

Notice. New forum software under development. It's going to miss a few functions and look a bit ugly for a while, but I'm working on it full time now as the old forum was too unstable. Couple days, all good. If you notice any issues, please contact me.

Forum Index : Microcontroller and PC projects : MRF557 RF Transistor...

Author Message
Grogster

Admin Group

Joined: 31/12/2012
Location: New Zealand
Posts: 9748
Posted: 02:07am 10 Jul 2017
Copy link to clipboard 
Print this post

Hello folks.


I'm looking for one of these transistors to repair a blown final in a Ramsey FM35 transmitter unit. Element-14 and DigiKey don't have any, Mouser have them but not till the end of August which is too long to wait.

Can anyone point me to a likely source for these?
Perhaps a member here may even have some they could sell me one or two of?
Smoke makes things work. When the smoke gets out, it stops!
 
CircuitGizmos

Guru

Joined: 08/09/2011
Location: United States
Posts: 1427
Posted: 06:59am 10 Jul 2017
Copy link to clipboard 
Print this post

If I had one or more, I'd send them your way.

Ebay?

http://www.ebay.com/itm/2PCS-MRF557-RF-Low-Power-NPN-Microwave-Transistor-Motorola-/121624098633?epid=1918228186&hash=it em1c515c7749:g:ZDoAAOSwymxVLx9g

Micromites and Maximites! - Beginning Maximite
 
robert.rozee
Guru

Joined: 31/12/2012
Location: New Zealand
Posts: 2461
Posted: 07:20am 10 Jul 2017
Copy link to clipboard 
Print this post

from the manual here:
http://shopramseyelectronics.com/1-watt-digital-fm-stereo-transmitter/
it looks like the output transistor is an MRF557. is this correct? (edit: i should have read the thread title!)

a possible subsitute / similar device listed in the MRF557 datasheet itself is the 2N3866, though the package is different. these are available from sicom here in christchurch and could be used as a stop-gap solution until you can get your hands on the right part.


cheers,
rob :-)Edited by robert.rozee 2017-07-11
 
Emady
Newbie

Joined: 02/02/2016
Location: United Kingdom
Posts: 23
Posted: 09:22am 10 Jul 2017
Copy link to clipboard 
Print this post

Try Rfparts.com I have used them many times.

Elia
 
crez

Senior Member

Joined: 24/10/2012
Location: Australia
Posts: 152
Posted: 01:15pm 10 Jul 2017
Copy link to clipboard 
Print this post

yep, rf parts has them, and I have not had a problem with them after many orders. An MRF237 would probably work well (maybe better - higher gain) but again a different package. The MRF237 does have emitter to case which makes it easier to heatsink.

David
 
Grogster

Admin Group

Joined: 31/12/2012
Location: New Zealand
Posts: 9748
Posted: 07:54pm 10 Jul 2017
Copy link to clipboard 
Print this post

Awesome, thanks guys. I will most likely order a few from them then.
Postage from America is usually a killer, but I will just add it to the job cost.
Smoke makes things work. When the smoke gets out, it stops!
 
mikeb

Senior Member

Joined: 10/04/2016
Location: Australia
Posts: 177
Posted: 08:07pm 10 Jul 2017
Copy link to clipboard 
Print this post

@Grogs

If postage is too much then give me a holla.
My son has a mate living in the US. He could buy them and post them to you.
I've saved a fortune doing it like that.

Regards, Mike B.
There are 10 kinds of people in the world.
Those that understand binary and those that don't.
 
Paul_L
Guru

Joined: 03/03/2016
Location: United States
Posts: 769
Posted: 08:42pm 10 Jul 2017
Copy link to clipboard 
Print this post

@Grogs

Let me know if I can help by shipping small things.

For 2 pounds

US Post 7-9 days $37
consolidator 4-5 days $65
UPS 3-5 days $100

Paul in NY
 
Print this page


To reply to this topic, you need to log in.

The Back Shed's forum code is written, and hosted, in Australia.
© JAQ Software 2025