Did anybody use MAR as a HF(1.8-28MHz) (not VHF) preamplifire?

What about results?
Any usable links or advices?

Thanks in advance.
MAc
sp9mrn

"MAc" wrote in message
...
Did anybody use MAR as a HF(1.8-28MHz) (not VHF) preamplifire?

What about results?
Any usable links or advices?

Thanks in advance.
MAc
sp9mrn

GM Mac, all the time! In a shop environment, not as an RF preamp on the air
since I don't have any need for that. I use an INA 02186 (roughly equal to
the MAR 8), to depress the noise figure of an old HP 312 selective Voltmeter
when I need it, Also MAR 4 to boost a DDS output that runs 7-35 MHz.

Unless you're running a very inefficient antenna, you shouldn't need a
preamp for anything 2-30 MHz with any reasonable receiver. I HAVE used the
above INA 02186 for a beverage antenna amplifier. Not for myself but for a
friend with a 500 foot beverage. Worked fine.

W4ZCB

Harold E. Johnson napisa³(a):
....
Unless you're running a very inefficient antenna, you shouldn't need a
preamp for anything 2-30 MHz with any reasonable receiver.

Thank You Harold.

I've read an article by IK4AUY from QEX Mar/Apr 2003 about Front-End
(standalone). He used very nice push-pull preamplifire in it (to
compensate insertion loss) - but i wanted to be smarter ;-)
And the question should be:

"If **I have decided to use RF preamplifire** CAN I use MMIC or should I
use more "conventional" solution. ;-)

73
MAc
sp9mrn

On Wed, 21 Feb 2007 13:57:39 +0100, MAc
wrote:

Did anybody use MAR as a HF(1.8-28MHz) (not VHF) preamplifire?

What about results?
Any usable links or advices?

The problem seems to be that they have a lot gain (especially MAR-8
with a huge gain below 100 MHz), not so spectacular output intercept
point, thus the input intercept point is quite low, which can cause
problems, if a broadband antenna signal is fed into it.

Even if you have sufficiently selectivity in front of the MAR, you
have to watch out for leakage capacitances around the filter, since
the amplifier has gain well into the VHF and UHF bands.

I once tried to use a MAR as a preamplifier for the 29 MHz satellite
band with a filter in front of it that I hastily, but since I have a
few FM-BC stations (100-200 W each) and VHF and UHF TV transmitters (a
few kW each) at 1-2 km distance, I got quite a lot of intermodulation
products from these on the 29 MHz.

So even if you are making a filter for HF, you still would have to be
careful about stray capacitances in the coils and stray inductances in
the capacitors, in order to keep the strong VHF/UHF signals out of the
MAR input :-).

Paul OH3LWR

I've read an article by IK4AUY from QEX Mar/Apr 2003 about Front-End
(standalone). He used very nice push-pull preamplifire in it (to
compensate insertion loss) - but i wanted to be smarter ;-)
And the question should be:

"If **I have decided to use RF preamplifire** CAN I use MMIC or should I
use more "conventional" solution. ;-)

73
MAc
sp9mrn

OK, in that case, the answer is NO. They haven't made an MMIC with the
characteristics of IK4AUY's preamp. Not even in the same zip code as the
characteristics of his pre-amp.

W4ZCB

I've read an article by IK4AUY from QEX Mar/Apr 2003 about Front-End
(standalone). He used very nice push-pull preamplifire in it (to
compensate insertion loss) - but i wanted to be smarter ;-)
And the question should be:

"If **I have decided to use RF preamplifire** CAN I use MMIC or should I
use more "conventional" solution. ;-)

73
MAc
sp9mrn

OK, in that case, the answer is NO. They haven't made an MMIC with the
characteristics of IK4AUY's preamp. Not even in the same zip code as the
characteristics of his pre-amp.

W4ZCB

Let me re-phrase that Mac, there's not an MAR that will match the
performance of the IK4 amplifier. RF Microdevices however, makes an RF2317
linear CATV Amplifier that if you operated two in push pull would probably
make it. You'd wind up with under a 5 dB noise figure, 15 dB of gain and an
IIP3 of +35 dBm. (Output Ip3 +50 dBm!)

The power requirements are not insignificant, a single one requires 9 Volts
at 175 mA. a pair, 350 mA.

W4ZCB

Harold E. Johnson napisał(a):

OK, in that case, the answer is NO.

The answer is Thank You

They haven't made an MMIC with the
characteristics of IK4AUY's preamp. Not even in the same zip code as the
characteristics of his pre-amp.

Ok I understood. Thanks for stopping me from making stupid things :-)

MAc
sp9mrn

Paul Keinanen napisał(a):

I once tried to use a MAR as a preamplifier for the 29 MHz satellite
band with a filter in front of it that I hastily, but since I have a
few FM-BC stations (100-200 W each) and VHF and UHF TV transmitters (a
few kW each) at 1-2 km distance, I got quite a lot of intermodulation
products from these on the 29 MHz.

Thanks

73
MAc
sp9mrn