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

Re: L on AO40

>From: "Walter Crauwels" <walter.crauwels@skynet.be>
>Wrong you should stay around 10db BELOW the beacon !!!
>Check on the operator pratice documents for AO-40
>Leila and the AGC circuit will love to see signals 10db below the beacon
>----- Original Message ----- 
>From: "L Clare Fowler" <lcfowler@magma.ca> 
>> I have an array of four times 27 turn helix ants with a
>> 70cm four way power divider.(1:1 SWR on third harmonic)
>> Theoretical gain 25db. Probably several db less. 
>> Feed line 30 ft hardline and 10 feet RG8.  
>> Using FT-736R barefoot with 10 watts.
>> Have had many solid QSO's with it.  However signal
>> is about 6db below beacon. Really need another 
>> 10 watts to hit bird at max allowable level. 
>> Clare VE3NPC
>> >  Just wondering what size and how many antennas people are using
>> >  for the L uplink on AO40. How much power?  Just ordered the 1.2Ghz
>> >  module for my 736 and wondered if it will useable barefoot on
>> >  AO40 (with hardline up to the antenna and 2 ring yagis) or if
>> >  I will need an amp.
>> >
>> >  -James
>> >  ki0kn@amsat.org

Hi James, Clare, Walter, John. etal:

Well in a perfect world Walter would be correct.  That assumes everyone is
using a 2.4G recieving system that can hear 20 dB below the beacon, but as
we know not all do.  So for them to hear you, the uplink power must exceed
the recommendation and venture higher toward the beacon level.  I have been
off the satellite for over a month but my experience on mode-LS was that
competition with loud mode-US stations made it difficult to get a decent
downlink signal.

I have about 9.5w at my 45-ele loop yagi [20 dBiv] on 1269.  Using that I
get just 6 dB over the noise floor.  It is workable but not strong.  I
think at least 3 dB more uplink is needed for comfortable but not strong
QSO's.  That seems the limit before costs skyrocket.  I will modify my
mode-L system which outputs 15w to put 14w at the antenna and hope it is

Those that are using a FT-736R [10w] might consider a 20w amp such as
Downeast Microwave makes or dl2am (that Tom Haddon, KV5VH markets in the
USA).  That can be mounted at the antenna terminal for max effect.  If you
can afford 40w that will cover most conditions, I believe...my 2 cents!   

Happy Thanksgiving from Alaska!

mode-L:  FT-847-->DEM 144/1268 Tx-conv (15w) -->45Loop yagi

Via the amsat-bb mailing list at AMSAT.ORG courtesy of AMSAT-NA.
To unsubscribe, send "unsubscribe amsat-bb" to Majordomo@amsat.org