[Date Prev][Date Next][Thread Prev][Thread Next] - [Date Index][Thread Index][Author Index]

re: TH-F6 RX for linear birds



    I am setting up a portable station for use with the linear birds. Has
     anyone used the Kenwood TH-F6 as RX with this satellites (FO-20,
     FO-29, AO-7, RS-12/13...)? I'm planning to use an Arrow antenna and
     an old Kenwood TR-751 as TX. Is it enough sensitive in SSB? Has it
     desense problems working mode J or mode A full-duplex?
    I have a Icom IC-R10 and I think that it is not enough sensitive and
     it has desense problems.

I've heard all of these with an Arrow equivalent, and worked FO-20, FO-29
and AO-10 (near perigree) using the same antenna and with a different 
transceiver.  However, with a wide front-end, the TH-F6A may not always
perform well in an urbanzed and/or high RF area.  So if you're already
having de-sense and/or intermod problems with the IC-R10, you may want 
to try the TH-F6A in your local area before you buy.  UO-14 has a strong
downlink, so don't use that as your test case.

Given a suitable a downconverter and an antenna comparable to an 'APRS' 
dish, it also receives AO-40 fairly well.   It does especially well with
an AIDC downconverter.  Nearly adjacent stations may be hard to separate, 
but that's more of an HF than a satellite issue. The only voice satellite
i haven't heard yet is RS-15 (probably for lack of a suitable antenna).  

However, de-sense from the uplink is an issue i haven't dealt with, as
in the past, there's either been a diplexer in my HT or externally, as i
had separate 2m and 70cm ports on the other rig, and my antenna uses the 
same elements for both bands.  On the other hand, the arrow uses separate
elements for 2m and 70cm, which are cross-polarized, so that should help 
the de-sense problem.  You might still need an external filter to keep 
2m out of your 70cm receive (see the ARRL Satellite Handbook for details) 
with an TH-F6A.  Maybe someone here else has more direct experience with 
this.

Your big issue may be the uplink, especially for AO-40.  With an Arrow
without a built-in diplexer, you should be fine with two rigs if your
transmitter has enough power (sorry, i don't know the specs on TR-751).  
However, you'd better make sure you're not getting too much RF exposure
if your antenna is handheld or tripod mounted nearby, especially if you
are trying to work AO-10 or AO-40.  Be careful of other people if you're
operating in a public place.

Note that it may not work well with an Arrow diplexer (e.g. don't get
one built into the handle), as it's designed for QRP operation and 
limited to 10W (which makes sense given it would be inappropriate to 
run more than that much power in Mode J-FM with an Arrow antenna). 

I do not recommend an TH-F6A for Mode J-FM however, unless you use another
rig for transmit.  It will hear the birds just fine (albeit not quite as 
well as my Alinco DJ-G5T, especially in urbanized areas) but the lack of 
full duplex operation makes it unsuitable for any kind of routine J-FM 
operation.  It is essential to hear your own downlink, at least in North
America and Europe, in order to avoid causing interference to other
stations.  I have not operated recently, but i can tell you that this 
has been a serious problem in the past, especially on transcontinental
passes.

73's and good luck!
			         -- KD6PAG
----
Via the amsat-bb mailing list at AMSAT.ORG courtesy of AMSAT-NA.
To unsubscribe, send "unsubscribe amsat-bb" to Majordomo@amsat.org



AMSAT Top AMSAT Home