Call Search
     

New to Ham Radio?
My Profile

Community
Articles
Forums
News
Reviews
Friends Remembered
Strays
Survey Question

Operating
Contesting
DX Cluster Spots
Propagation

Resources
Calendar
Classifieds
Ham Exams
Ham Links
List Archives
News Articles
Product Reviews
QSL Managers

Site Info
eHam Help (FAQ)
Support the site
The eHam Team
Advertising Info
Vision Statement
About eHam.net

   Home   Help Search  
Pages: [1]   Go Down
  Print  
Author Topic: HF amp 300 watt mrf247x2  (Read 2070 times)
KK4KGE
Member

Posts: 3




Ignore
« on: April 02, 2013, 07:15:18 PM »

HF amplifier 300 watt mrf247x2
This HF amp is advertised on EBAY and I am considering buying it.
Does anyone have a review for this? How is it?

Thanks..
Alby KK4KGE
Logged
W9GB
Member

Posts: 2577




Ignore
« Reply #1 on: April 02, 2013, 09:18:45 PM »

Alby --

eHam.net has an amateur radio HF Amplifier Review Section !!
http://www.eham.net/reviews/products/10

VERY SIMPLE RULES to identify illegal CB amps.

1. There are only a very small number of amateur radio HF amplifier mfg.
2. KK5DR made a buying guide for NOOBIES.  READ IT.

Rates-an-amp by Matt Erickson, KK5DR
http://www.kk5dr.com/amplist.htm

3.  Does the amp look like an import, or someone built in basement ?
(Palomar, Dave Made, Magnum, X-Force, Texas, etc.) --
pass another illegal CB amplifier for ignorant buyers.
4. Does the amplifier have a name that is appealing to the trucker sub-culture ?
PASS
===
IF the amplifier is NOT in Matt, KK5DR amplifier list OR listed in eHam.net Reviews ===
PASS, and Save $$ for GOOD purchase.  IF you buy Junk -- it has No Resale value!
« Last Edit: April 02, 2013, 09:26:29 PM by W9GB » Logged
QRP4U2
Member

Posts: 106




Ignore
« Reply #2 on: April 02, 2013, 10:09:36 PM »

HF amplifier 300 watt mrf247x2
This HF amp is advertised on EBAY and I am considering buying it.
Does anyone have a review for this? How is it?

Thanks..
Alby KK4KGE

A piece of bandsplattering piece of junk. I would stay away from it.

Save up your money and buy a decent amp.
« Last Edit: April 02, 2013, 10:26:04 PM by QRP4U2 » Logged
K6AER
Member

Posts: 3468




Ignore
« Reply #3 on: April 03, 2013, 08:00:57 AM »

The MRF-247 is a 70 watt class C transistor with about 6 dB of gain. It is used for FM mobile amplifiers and even when biased for linear operation makes for a very poor class AB transistor. A pair of these devices run in Class AB would only be able to provide about 100 watts out and the IMD would be no better than 20 dB second to third.

The device design on the MRF-247 is from about 1993.
Logged
KD0REQ
Member

Posts: 836




Ignore
« Reply #4 on: April 03, 2013, 09:49:36 AM »

one question only... ask "What is the FCC type acceptance number?"

one action only... then go to the fcc site and look that up.  if they hijacked the type acceptance (doesn't look the same, specs not the same, etc) then report to both FCC and eBay.

if it matches, and there is an online manual that says it's right for the service you seek, then consider it.
Logged
W4OP
Member

Posts: 388


WWW

Ignore
« Reply #5 on: April 03, 2013, 10:47:57 AM »

I'll just add that none of these amps have band by band low pass filtering (thus the lack of a bandswitch). So unless you add the appropriate LPF's you can count on hearing from an OO or the FCC.
Unfortunately, these amps are flooding the amateur market and few buyers have the knowledge to discern what they are buying.

Dale W4OP
Logged
Pages: [1]   Go Up
  Print  
 
Jump to:  

Powered by MySQL Powered by PHP Powered by SMF 1.1.11 | SMF © 2006-2009, Simple Machines LLC Valid XHTML 1.0! Valid CSS!