[amsat-bb] Best Mast mount PA/LNA?

[Zach Leffke]

Bob,

For LNAs:
I'll throw in a vote for ARR as well.  I personally own both their 
receive only pre-amps and the model referenced in the link below for 
2m/70cm.  The VT amateur radio club has used them in the past as well 
(and will be again in the near future).  Additionally, the big ground 
station we are building at VT (separate from the amateur radio club, 
calling it the VTGS) will also be using them on 2m, 70cm, and for the 
NOAA 137MHz birds.  I have had great success with them.

I did a massive survey to try to answer this question for the VTGS 
design and finally settled on the ARR devices.  Down East Microwave and 
Kuhne Electronics were high on the list, but they only sell RX only 
pre-amps, requiring you to come up with your own solution for the 
bypassing/sequencing for TX.  I think M2 Antennas has an option or two, 
but they are super high quality and super expensive (I think geared more 
towards kW operations and EME work).  The models referenced KB1PVH below 
have a built in RF Sense circuit for automatically switching for TX 
operations, but if you are like me and nervous about the RF sense stuff 
failing and cooking your pre-amp, they have a PTT signal built in for 
use with an external sequencer.  They can handle up to 160W when in TX 
state.  For the quality of the product (RX performance, and weather 
proof mast mountable), ease of use on TX (rf sense or ptt), and the 
price point, ARR was the way to go for us.  One final bump for them is 
their customer service.  I discussed this with them during my survey for 
the VTGS design and they basically said that if you accidentally cook 
one of their pre-amps, the cost to repair it is minimal (not much more 
than the cost of shipping).

For PAs:
I also did a big survey to try to answer this question as well.  The 
options I looked at included some designs from W6PQL based on the 
mitsubishi RF MOSFET modules (with the right filtering!!!, 
www.w6pql.com), the designs from Down East Microwave based on the MOSFET 
modules (no filtering though), some commercial broad-band amps that 
cover 2m/70cm, the very common Mirage brick amps, and finally Kuhne 
Electronics (out of Germany).  For the VTGS we have a bit different 
setup that uses SDRs on the backend instead of traditional HW radios.  
The devices we are using (Ettus USRPs with WBX/SBX daughterboards) only 
put out about 100mW max output on the Amateur Satellite bands.  So I 
needed to get from about 100mW to about 100W and ensuring that I meet 
FCC limits for out of band performance.  I finally settled on some 
products from Kuhne Electronics that can achieve full drive of 60W with 
about 10mW on the input and have built in filtering to meet FCC limits.

If your looking for a mast mounted PA, you might want to consider the 
Mitsubishi RF Modules (be careful about harmonics, and out of band 
emissions!) and the designs from W6PQL.  He also offers some good 
filters that provide (1) the required suppression for out of band 
emssions and (2) RF detection ports for monitoring fwd/rev power 
levels.  This could be a fairly compact design that could be integrated 
into a weatherproof enclosure and mounted on the mast. Its not a canned 
solution that you can just buy though.  Someone would have to do the 
detailed design work, and then actually build everything, I'm just 
throwing it out there as an idea.

It sounds like the simplest "swap option" to replace your existing 
hardware might be the Mirage amps (http://www.mirageamp.com/).  They 
have built in pre-amps, can get you up to around 160W or so on 2m 
(model: B-1018-G) and 100W on 70cm (model: D-1010-N) with about 10W 
drive, have the TX/RX circuitry built right in, and have the right 
filtering.  I have only ever used them with the manual ssb/fm switch, so 
for mast mounting I think they have a remote control head that can be 
used to pick which mode your in from the schack (instead of going up on 
the roof and flipping the ssb/fm switch).  It sounds like you might be 
able to directly replace your existing gear with these devices, and it 
might be the easiest route.  Maybe some of these with better weather 
proofing (they're not designed for outdoor use), and maybe better 
cooling (though at low duty cycle use like packet, that might not be 
much of a concern).

Even though the Mirage amps have built in pre-amps, I'd still think 
about putting the ARR gear inline closer to the antennas and using 
sequencers, they are really good performers on RX.


-Zach, KJ4QLP

On 6/4/2015 12:01 PM, David L Warnberg wrote:
> I can second that, I have them on my egg beaters and they work very well..
>
> David  KK4QOE
>
> -----Original Message-----
> From: AMSAT-BB [mailto:amsat-bb-bounces at amsat.org] On Behalf Of Dave Webb
> KB1PVH
> Sent: Thursday, June 04, 2015 10:04 AM
> To: Bob Bruninga
> Cc: AMSAT -BB
> Subject: Re: [amsat-bb] Best Mast mount PA/LNA?
>
> Bob,
>
> I've had good luck with ARR preamps.
>
> http://www.advancedreceiver.com/page10.html
>
> Dave-KB1PVH
>
> Sent from my Samsung S4
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> _______________________________________________
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