Discussion:
Topband: Request from FK8CP
David Raymond
2007-04-04 15:03:19 UTC
Permalink
A couple of days ago, I received a QSL card from Remi, FK8CP. Enclosed with
the card were two separate full page, single spaced letters requesting help.
Letter #1 requests technical assistance. Letter #2 discusses his operating
habits, needed countries, etc. The information Remi was conveying is fairly
extensive but can be boiled down to several key points as follows:

1. The amplifier that Remi recently got has developed a problem (he didn't
specify the problem or the symptoms). He believes the problems are with two
faulty PIN diodes, type MA4P4006D. He is looking to find a pair "at a very
cheap price (even used but in good order)."

2. He lives on a small lot, approximately 30m x 23m. His transmit antenna
is a "sloping dipole (inverted U) hanging between a metal mast and the
tower." He has problems with QRN and hearing in general. He is currently
using "shielded loops with preamp, SEM QRM eliminator, etc but the results
(S+N/N) are not good...on average nearly the same as with the sloping
dipole." He has not yet tried pennants or flags. He is looking for:
A. Suggestions on simple receive antennas that will fit in his space.
B. Methods to minimize noise be re-radiated by the TX antenna and/or mast
and tower (he
uses QSK extensively)...detuning, etc.
C. He is looking for recommendations for a good 160m preamp.
D. He is looking for accessories that can aid in noise reduction..."DSP,
noise canceller,
etc."

3. The letter discussing his operating procedures can be summed up as
follows:
A. His typical 160m QRG is 1831 kHz.
B. His QSX for JA is 1810 - 1813 kHz.
C. His QSX for NA (and the rest of the world other than JA) is 1833 - 1835
kHz.
D. He transmits "slow speed" with "full QSK"
E. He requests stations call at 10 wpm or less
F. Once he has responded to your call "kindly send RRRRRRR, your callsign,
my RST"
G He tries to be on daily at least one hour prior to his sunrise, earlier
on Saturday
and Sunday UTC

4. His needed countries list includes:
EU/AS: C3, CN, CT1, CT3, CU, EA9, GJ, GU, HB0, HV, HZ, JW, JX, JY, LX,
OH0, OX, OY, SV5, SV9, T7, T9, TA, TF, TK, UC, UD, UF, UG, UH, UI, UJ, UM,
YL, Z3, ZA, ZB, ZC, 4K, 4U, 7X, 9H
Africa: need all countries EXCEPT EA8, FR, VQ9, 5T, 6W, 7Q
In the Americas: C6, CO, CP, CY9, CY0, FJ, FP, HC, HI, HK0, HP, J7, J8,
KG4, KP1, KP5,
PJ8, TG, V4, VP2M, YN, 4U, 6Y, 8R
Asia: 3W, 4S, 9N, A5, AP, BV, BY, 3P, HS, JD/M, JT, VU, VU/A, XU, XW, XY,
YA, YI, YK
And...the "very rare ones"

5. He would like to run schedules with anyone on the "needed" list above,
or with anyone that
needs him.

Remi's contact information is as follows:

Remi Touzard, FK8CP
B.P. 945
98845 Noumea Cedex
New Caledonia
FAX: +687 28 10 33

He makes no mention of having email or internet capability. For starters,
it would probably be helpful for Remi to get a copy of ON4UN's "Low-Band
DXing" book if he doesn't already have one.

73 to all...Dave
W0FLS
Dan Zimmerman N3OX
2007-04-04 18:40:34 UTC
Permalink
I have a 13 foot x 6 foot flag and a 60 foot base loaded vertical on
a smaller lot than Remi's, and I have found that the decoupling issue
is exceedingly important, especially since the flag gives such a
modest (but generally worthwhile) improvement in S/N.

On 160m, my flag is about 0.05 wavelengths away from the vertical. I
have a convenient built-in ability to detune it because the antenna
has matching networks for 30m and down selected by a motorized rotary
switch... I set up a footswitched T/R system to move the switch a
half-position to disconnect the vertical from the loading coil, and
when I A/B the flag with the resonant TX antenna connected and
disconnected I can get between a 3 and 7 S-unit difference for signals
off the rear of the flag! (Sorry I don't have that in dB... I didn't
measure it, I just wanted to eliminate it).

The situation is better when the TX vertical is located directly off
the back of the flag, but there's still a major degradation of the
pattern from what I can hear. No surprises here. EZNEC shows that
the flag + vertical pattern is almost completely omnidirectional for
most orientations of the flag. It's got some directivity if the flag
is pointed directly away, but it's significantly degraded.

I bet a DPDT relay (sped up ... plenty of discussion here lately) at
the dipole feedpoint would suffice to get the TX antenna out of the
picture as far as pickup and reradiation goes. QSK is tough but 10WPM
QSK at least relaxes the speed requirements a little. A couple of
floating quarterwaves won't cause trouble.

The tower probably needs a resonant detuning section... sending a copy
of Low Band DXing along really does sound like a great idea... all
this is in there.

For what it's worth, the flag is really starting to shine now that
major thunderstorm activity is cropping up in the states. I've been
using it more on 80m than 160 and listening to EU and it's nice to
have your back to the QRN, so to speak.

73,
Dan
Michael Tope
2007-04-06 02:20:01 UTC
Permalink
----- Original Message -----
From: "David Raymond" <daraymond at iowatelecom.net>
To: "Topband" <topband at contesting.com>
Sent: Wednesday, April 04, 2007 8:03 AM
Subject: Topband: Request from FK8CP
Post by David Raymond
A couple of days ago, I received a QSL card from Remi, FK8CP. Enclosed with
the card were two separate full page, single spaced letters requesting help.
Letter #1 requests technical assistance. Letter #2 discusses his operating
habits, needed countries, etc. The information Remi was conveying is fairly
1. The amplifier that Remi recently got has developed a problem (he didn't
specify the problem or the symptoms). He believes the problems are with two
faulty PIN diodes, type MA4P4006D. He is looking to find a pair "at a very
cheap price (even used but in good order)."
David,

I sent Alpha an email inquiring about the MA4P4006D and they wrote back
and pointed me to the Alpha Radio Products webstore:

http://alpharadioproducts.com/merchant5/merchant.mvc?Screen=CTGY&Store_Code=AS&Category_Code=A87

The email I got from Molly W0MOM wasn't entirely clear on this, but
she implied that the MA4P4006D was the transmit pin diode. These
are listed as P/N DPX-X112 on the website and they go for $125.00
each. The receive pin diodes are listed as P/N DPX-X103 and go for
$12.00 each. Anyone know for sure if the MA4P4006D is the TX
or RX pin diode in the Alpha 87?? Here are some specifications that
I found on the web for the diode:

Part Number = MA4P4006D
Manufacturer Name = Various
Description = General Purpose PIN Diode
Diodes per Package = 1
V(BR) Min.(V)Breakdown Voltage = 600
V(FM) Max.(V) Forward Voltage = 1.0
@I(FM) (A) (Test Condition) = 100m
Ct{Cj} Nom. (F) Junction Cap. = 2.2p
@V(R) (V) (Test Condition) = 100
t(carrier)(S),Carrier Lifetime = 6.0u
@I(F) (A) (Test Condition) = 10m
r(s) Max.(k) Series Resist. = 0.5
@I(F) (A) (Test Condition) = 100m
@f(res) (Hz) (Test Condition) = 100M
Package = Screw
Military = N


Thanks,

Mike W4EF.........................

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