Topband: That radar on 1915...

[JC]

Mike

Very interesting signal. I tuned on 3260 and the radar signal was very
strong and let's say unique, two bursts, one narrow band another wide band. 

It turns out that I am testing several preamplifiers and the signal on 3260
was Intermodulation coming from the preamplifier. I removed the preamplifier
and listening on the iC7800 the signal is not there.

This is a very serious problem all of us is facing nowadays and it is hard
to even figure I out what is happening. 

Two week ago  I noticed an intermodulation signal on 1890, I recognized the
AM broadcast program and I was able to identify the two station generating
the intermodulation,  I was expecting two local AM BC below 1.8 MHz. for my
surprise both signal was SW, 11,930 MHz and 13,820 MHz , same station Radio
Martã 1890 KHz apart.

With the solar activity peaking the propagation  is  exceptional good on
6MHz to 9 MHz  or 12 MHz and others SW bands. The two station from Radio
Martã was arriving here in Ft Lauderdale with -20 dBm with peaks -10 dBm,
any preamp with 10 db gain will delivery to the radio 0dBm, this is 1 mW
!!!! most radios with IP3 bellow 40 dB  cannot handle that level of energy
without distortion and intermodulation.

Most RX antennas have low gain on 160m and requires a preamplifier, however
the same antennas can have some good gain on 12 MHz. With the propagation so
good on SW the broadcasting are causing  a lot of problems.

Most of us are not using tunable pre-selector ahead of the preamplifier as
we are used to have on old tubes receivers.

The Radio Martã is not near my house, it is in South Carolina and I'm in
South Florida.  Last Sunday I measured s9+60 dB  from a  BC signal without
preamplifier  on 7 315 . this is - 13dBm, with any preamplifier with more
than 10 dB we can send almos 1 mw to the receiver front end.

I try to check 7315 and there are several BC on that frequency form 5 to 250
KW...  

This situation with the propagation can last another year or two. Check if
your preamp is not overloading from SW boradcat signals. We need
preselectors or a low pass filter. 


See what I found on 7.315 MHz

7315	ADVENTIST WORLD R.	03:00	03:30	1234567	Tigrinya	250
125 KW	FIssoudun	46N57 001E59	OFF_AIRMBR
7315	Radio Tamazuj	04:00	04:29	1234567	Sudanese Arabic	250 KW	146
CVASanta Maria di Galeria	42N02 012E18	OFF_AIRPNW/FPU
7315	Radio Dabanga	04:29	05:57	1234567	Sudanese Arabic	250 KW	146
CVASanta Maria di Galeria	42N02 012E18	SIGNAL_STRENGTH_2PNW/FPU
7315	AIR Shillong	06:56	09:31	1234567	Hindi	50	76
INDShillong	25N33 091E56	OFF_AIR
7315	CHINA RADIO INTERNATIONAL	16:00	16:57	1234567	Vietnamese
100	184	CHNKunming	25N10 102E49	OFF_AIR
7315	CHINA RADIO INTERNATIONAL	17:30	18:27	1234567	Chinese	500
300	CHNKunming	25N10 102E49	OFF_AIR
7315	CHINA RADIO INTERNATIONAL	22:00	22:57	1234567	Esperanto
500	294	Kashi-Saibagh 2022	39N21 075E45	OFF_AIR
7315	CNR 2	09:00	16:04	1234567	Chinese	150	ND	CHNXian 594
34N23 108E40	OFF_AIR2
7315	CNR 2	20:55	01:00	1234567	Chinese	150	ND	CHNXian 594
34N23 108E40	OFF_AIR2=11660
7315	TWR Africa	14:25	14:55	1234567	Portuguese	50	5
SWZManzini	26S19 031E36	OFF_AIR
7315	TWR Africa	14:55	15:10	1234567	Makhuwa	50	5
SWZManzini	26S19 031E36	OFF_AIR
7315	TWR Africa	15:10	15:55	1234567	Lomwe	50	5
SWZManzini	26S19 031E36	OFF_AIR
7315	VOICE OF AMERICA	19:00	20:00	1234567	Kurdish	100	105
DBiblis	49N40 008E30	OFF_AIRIBB/
7315	WHRI CYPRESS	00:00	00:30	12.....	English	250	173
USACypress Creek	32N40 081W08	OFF_AIR1 a14
7315	WHRI CYPRESS	00:30	01:00	.234567	English	250	173
USACypress Creek	32N40 081W08	OFF_AIR1 a14
7315	WHRI Water of Life Ministries	00:30	01:00	1......	English	250
173	USACypress Creek	32N40 081W08	OFF_AIR1 a14
7315	WHRI Water of Life Ministries	01:00	01:30	.2.....	English	250
173	USACypress Creek	32N40 081W08	OFF_AIR2 a14
7315	WHRI CYPRESS	01:00	02:00	12.....	English	250	173
USACypress Creek	32N40 081W08	OFF_AIR2 a14
7315	WHRI CYPRESS	02:00	03:00	1234567	Spanish, English	250
152	USACypress Creek	32N40 081W08	OFF_AIR1 a14
7315	WHRI CYPRESS	05:30	09:00	1234567	Spanish, English	250
152	USACypress Creek	32N40 081W08	OFF_AIR1 a14
7315	WHRI CYPRESS	10:00	12:00	.23456.	Spanish, English	250
173	USACypress Creek	32N40 081W08	OFF_AIR1 a14
7315	WHRI Christian Worship Hour	11:00	12:00	1......	English	250
173	USACypress Creek	32N40 081W08	OFF_AIR1 a14
7315	WHRI Water of Life Ministries	12:00	12:30	1......	English	250
173	USACypress Creek	32N40 081W08	OFF_AIR1 a14
7315	WHRI CYPRESS	12:00	13:00	1234567	Spanish, English	250
173	USACypress Creek	32N40 081W08	OFF_AIR2 a14
7315	WHRI CYPRESS	20:00	21:00	1234567	English	100	25
USACypress Creek	32N40 081W08	OFF_AIR2 a14
7315	WHRI CYPRESS	21:00	22:00	1.34567	English	100	25
USACypress Creek	32N40 081W08	OFF_AIR2 a14
7315	WHRI CYPRESS	22:00	00:00	1234567	English	250	173
USACypress Creek	32N40 081W08	OFF_AIR1 a14
7315	WHRI Eternal Good News	23:45	00:00	1......	English	250	173
USACypress Creek	32N40 081W08	OFF_AIR


-----Original Message-----
From: Topband [mailto:topband-bounces at contesting.com] On Behalf Of
mstangelo at comcast.net
Sent: Thursday, January 15, 2015 9:41 PM
To: Doug Grant
Cc: topband at contesting.com
Subject: Re: Topband: That radar on 1915...

Hearing it on 3260 0240UTC here in New Jersey.

Mike N2MS
----- Original Message -----
From: Doug Grant <dougk1dg at gmail.com>
To: topband at contesting.com
Sent: Thu, 15 Jan 2015 22:24:02 -0000 (UTC)
Subject: Topband: That radar on 1915...

Has anyone heard it recently? I have not been on 160 much since the first of
the year.

I heard it this afternoon on 3250 (it also has been heard on 4400 and 5300
kHz).

Thanks & 73,

Doug
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