I have had a problem occur when using an loop receiving antenna on the aux
receive antenna input when transmitting on the main dipole (with a Yeasu
990). I had to put crossed diodes on the aux input. I think you will need
something like this. I used 1N916 diodes...approx four of them, two one way
and two the other across the center conductor to shield...right at the input
of the receiver. Actually, I put them inside the shell of the male connector
on the receive coax. Experience with NMR receivers has shown me that a
simple passive ckt of two to four crossed diodes is hard to beat for
simplicity and pretty effective. I measured about 5 vpp of rf at 75M with
this setup at the receive aux input. Down from about 25 vpp without the
diodes. That was enough of an improvement to protect the 990 from having
it's ALC disabled which was happening with the 25vpp.
I am interested to hear other's experiences with this issue...and on the
Orion.
Chuck, KE9UW
> -----Original Message-----
> From: tentec-bounces@contesting.com
> [mailto:tentec-bounces@contesting.com]On Behalf Of Jan Palmquist
> Sent: Wednesday, January 05, 2005 9:45 AM
> To: TenTec@contesting.com
> Subject: [TenTec] Orion RX antenna input
>
>
> I plan to use my Orion more efficient with both
> receivers on different antennas.
>
> One question comes up.
>
> How much RF can the extra RX antenna input handle?
> Can I damage something if I have to much RF on it?
>
> I have antennas that are very close, a few meters.
> When I run kW on one antenna there will be a lot
> of RF into the other antenna, probably several Watts,
> and that power will go straight into the input circuits
> of the receiver connected to "RX ANT", or?
>
> I have looked at the circuit diagram and see no protection,
> there are a lot of relays, but I assume they don't switch
> between TX and RX, or? "ANT 1" and "ANT 2" have diodes
> muting the signal in TX mode, bot not "RX ANT"
>
> I don't like to put a safety circuit on RX ANT input if it
> isn't necessary. There are nothing in the manual of this
> either.
>
> Anyone done this succesfully?
> or more important, Has anybody done this and burnt something?
>
> 73's de Jan - SM5FUG
> _______________________________________________
> TenTec mailing list
> TenTec@contesting.com
> http://lists.contesting.com/mailman/listinfo/tentec
>
--
No virus found in this outgoing message.
Checked by AVG Anti-Virus.
Version: 7.0.300 / Virus Database: 265.6.8 - Release Date: 1/3/2005
_______________________________________________
TenTec mailing list
TenTec@contesting.com
http://lists.contesting.com/mailman/listinfo/tentec
|