Re: [amsat-bb] BEST satellite radio

[Ronald Long <rlong3@xxxxxxxxxxxxxxx>]

Franklin Antonio wrote:

  >Opinions please: What is the best satellite radio?

Currently I have an ft-736 and ic-275/475 pair.

There seem to be limitations on all of the radios but here are a few comments.

I have so-far stayed away from the main-band/sub-band radios such as 
ic-970, ic-820, ic-821, ts-790 etc. The reason has to do with the fact that 
you must transmit on the main band and receive on the sub band. It seems to 
me that the sub-band receiver is less capable than the main band receiver. 
The ts-790 is quite old now but let me use it as an example of the 
deficiencies of the sub-band concept. RIT works on main band only; Noise 
blanker (not sure); no IF Shift; no CW filter option.

Then there are just annoying things. I want a display of frequency and a 
tuning knob for receiving that are not compromised. Some of the sub band 
designs force you to use a little tuning knob, a poor S-meter, and small 
digits for display of receive frequency.

Some of the sat radios have not had VOX. A serious problem IMHO.

Another thing I found when using click-tuning with a telemetry modem. The 
radios vary a lot, depending on mode etc. Some just tune in too coarse 
steps to be usable. I have kept a file on this but I won't bore you with 
the details.

Some people would say that this is all a big deal over nothing. You don't 
need a very good receiver for satellite work. Well maybe they are right.

What am I going to do? So far I plan to keep the radios I have. Even though 
my ft-736 has a 1.2GHz module I will consider buying a mast-mounted 'power 
mixer'.

For example there are two 'power mixers' (which is a transverter without 
the receive part). The UTM-1200 DLX is a mast mounted unit. 144 input and 
15 watts out on 1268-1270. temp stabilized oscillator, rf sense operation, 
adjustable drive. www.ssbusa.com/

Kuhne has one also. MKU 13 OTX. power output 0.5 watts. Companion 15 - 20 W 
linear available. There is a picture of this one at www.db6nt.com/

For 1.2GHz I am assuming that a helix antenna and 10-15 Watts at the 
antenna will be sufficient. If I use a radio with 10 Watts at the ground I 
will probably only have 5 or less at the antenna even with the most 
expensive feedline (60 - 75 feet in my case). So a mast-mounted power amp 
will be needed. So why not just use one of these new power mixers and feed 
it with 144 MHz and any old coax.

This presents a problem for 2.4 GHz. Most of the receive converters convert 
to 144. There are a few designs around that go to 435 MHz which is what 
will be required.

Since I am so concerned about having the best receiver and since I already 
have several 2.4GHz to 144 MHz converters, I may add a 144 to 28MHz 
converter in series and use my HF radio for receive. I have one of the 
fancier HF radios with lots of IF filter choices, DSP noise reduction, NB, 
Passband tuning, and on and on. So why not use it? It also has a separate 
receive antenna input which would avoid the danger of transmitting into the 
satellite receive converter(s).

Just a few thoughts. ron w8gus.


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