Makes sense, Lee
Charlie
-Original Message-
From: Topband [mailto:topband-boun...@contesting.com] On Behalf Of Lee K7TJR
Sent: Monday, August 31, 2015 12:44 AM
To: topband@contesting.com
Subject: Topband: KD9SV-OK1RR relays ??? (RX Front End Protector)
I believe the point of having
FYI - The S-QSK boards are now spoken for. Thanks for the replies.
Paul, W9AC
_
Topband Reflector Archives - http://www.contesting.com/_topband
Another option for "front end" sequencing control involves the use of a
microcontroller to time R=>T and the the reverse switching events. For the
past two years, I've been using an Arduino Nano-based controller to manage
amplifier switching as well as a PIN diode T/R switch to silently
The Array Solutions device also uses the transformers to increase the
voltage at the diodes then steps it back down which means that the diodes
are not doing their limiting at 50 ohms. Therefore, your set of 2 series
diodes or even one diode each direction is limiting at a higher power
level
, August 30, 2015 8:41 AM
To: Tom W8JI ; Charles Cu nningham ; 'topBand List'
Subject: Re: Topband: KD9SV-OK1RR relays ???
Tom and all members of the list thanks for your ideas and time .
I have a plan B:
I added a BNC female connector in the rear panel of my old Yaesu, FT747
How about back-to-back 1N4148 diodes (2 in series) across the RX path, and
a #47 incandescent lamp between those and the Beverage? That's what I do
here, among other things.
Those are in series with my preamp, which is almost always on. There's also
some variable resistance in series with the
,
or strong BC stations.
73,
Charlie, K4OTV
-Original Message-
From: Topband [mailto:topband-boun...@contesting.com] On Behalf Of Mike
Waters
Sent: Sunday, August 30, 2015 3:52 PM
To: Charles Cunningham
Cc: topband; Tom W8JI
Subject: Re: Topband: KD9SV-OK1RR relays ???
How about back-to-back
The mast of my RX flag is 20-25 ft from my 160/80m shunt fed tower. I run a KW+
on the low bands. I use an Array Solutions AS-RXFEP RF Limiter (aka FES etc.)
in line with the flag at the rig’s RX Ant IN. The RXFEP uses a gas discharge
tube and a pair of matching transformers with back-to-back
Array Solutions offers a 'RX Front End Protector' based on back-to-back
1N4148 diodes.
Schematic:
http://www.ok1rr.com/public/rxfep.png
more details:
http://www.arraysolutions.com/Products/as_rxfep.htm
manual (also pictures of clipping etc.)
I added a BNC female connector in the rear panel of my old Yaesu, FT747 (It
is an FT80C, the commercial version with metallic chassis) few months ago.
I was using that BNC to feed an SDR receiver using the same antenna.
If i add a SPDT switch also on the rear panel and RE-WIRE the BNC
Cu nningham ; 'topBand List'
Subject: Re: Topband: KD9SV-OK1RR relays ???
Tom and all members of the list thanks for your ideas and time .
I have a plan B:
I added a BNC female connector in the rear panel of my old Yaesu, FT747 (It
is an FT80C, the commercial version with metallic chassis
, 2015 12:27 AM
Subject: Re: Topband: KD9SV-OK1RR relays ???
It seems to me that a very fast operating preamp protection circuit could
be
constructed employing a good fast saturating NPN switching transistor
across
the antenna path. In receive mode the collector-base junction would have
Tom -
Maybe we should say backwards T/R relay when we mean the reverse, of
what we did with real T/R relays when I was a kid. All of my rigs used
120VAC outboard relay coils!
FT-747 is indeed notorious for T/R timing issues, its semi-break-in so
severely truncating the leading element on CW
don't have
the URL to Measures' site but it can probably be found by a search.
73, Larry W6NWS
-Original Message-
From: Douglas Ruz (CO8DM)
Sent: Sunday, August 30, 2015 8:41 AM
To: Tom W8JI ; Charles Cu nningham ; 'topBand List'
Subject: Re: Topband: KD9SV-OK1RR relays ???
Tom and all
30, 2015 8:42 AM
To: Tom W8JI w...@w8ji.com; Charles Cu nningham
charlie-cunning...@nc.rr.com; 'topBand List' topband@contesting.com
Subject: Re: Topband: KD9SV-OK1RR relays ???
Tom and all members of the list thanks for your ideas and time .
I have a plan B:
I added a BNC female connector
On Sun,8/30/2015 7:32 AM, Larry wrote:
Measures (K6???) did a relay speed-up scheme for QSK on an SB220, I
don't remember the details but it was something like hitting the relay
with higher than usual coil voltage/current and it shortened up the
relay pull-in time.
My neighbor, Bob Wolbert,
I'm not sure goosing the pull-in voltage is always a good idea. It may
shorten the initial closing time a bit, but (depending on the relay)
it can aggravate contact bounce, doing more harm than good. It also
stresses the relay.
Done properly, it doesn't hurt a thing. The proper way is to use
That's similar to mine, but mine has two 1N4148 diodes in series,
back-to-back, total of four diodes.
However, after I did that, I got to thinking that it would be better with
only two. Or that there was no need for four. (Don't ask me to explain,
it's been a long time since I've thought about
the circumstances
and would it satisfy the suggestions of Tom (W8JI) about the transfer speed.
There may be better schemes around or even relays that are fast enough.
73, Larry W6NWS
From: Garry Shapiro
Sent: Sunday, August 30, 2015 6:27 PM
To: Larry
Subject: Re: Topband: KD9SV-OK1RR relays
That's similar to mine, but mine has two 1N4148 diodes in series,
back-to-back, total of four diodes.
However, after I did that, I got to thinking that it would be better with
only two. Or that there was no need for four. (Don't ask me to explain,
it's been a long time since I've thought about
remember the details but it was something like hitting the relay with higher
than usual coil voltage/current and it shortened up the relay pull-in time.
It might be more complicated in this application than needed. I don't have
the URL to Measures' site but it can probably be found by a search.
Hello to All;
Many years ago Alpha used a very nice QSK sequencing circuit for the Alpha 77,
NOT 77DX,D,SX, just the plain 77 ( 1971). It used a RJ1a and a reed-relay, a
couple of diodes and a resistor. It was powered with 55 volts. Worked very good
and I have the diagram. I have used it for
[mailto:topband-boun...@contesting.com] On Behalf Of Mike
Waters
Sent: Sunday, August 30, 2015 6:23 PM
To: mar...@centrum.cz
Cc: topband
Subject: Re: Topband: KD9SV-OK1RR relays ??? (RX Front End Protector)
That's similar to mine, but mine has two 1N4148 diodes in series,
back-to-back, total of four diodes
Perhaps common-mode isolation of currents induced in the antenna coax shield??
Charlie, K4OTV
Lee K7TJR k7...@msn.com wrote:
Hmmm, I wonder why the Array Solutions circuit board picture shows MCL 1:1
transformers.
Sounds fishy to me. Even the waveform pictures show clipping at a
/75 ohm feedline to a higher impedance of 800-1000 ohms.
73, Charlie, K4OTV
-Original Message-
From: Topband [mailto:topband-boun...@contesting.com] On Behalf Of Lee K7TJR
Sent: Monday, August 31, 2015 12:17 AM
To: topband@contesting.com
Subject: Topband: KD9SV-OK1RR relays ??? (RX Front
Since I am the original reason that Gary KD9SV built the first Front End
Saver device after we determined why I blew the front end many many
years ago of my IC-765 radio. I thought I might add one more very important
thing to what ever version of a Front End saver you guys decide to buy or
Sorry Charlie, I don't think I made my thoughts very clear.
James was quoting from a QST article that there was an impedance
transformation because of the transformers.
This was to make a higher voltage at the diodes. My point was that if the
transformers being used on their circuit board
I believe the point of having the transformers in their circuit is to
limit the maximum output.
A transformer (ferrite in this case) can only output whatever maximum
current determined by the core saturation level. They are relying on this
property of the transformers to limit the current into
Hi Martin, OK1RR,
I tried email direct to you but it was not possible. I am sorry about the
other member of the list.
It is about the FRONT END SAVER relays:
I have two different relays here and i would like to know if i can use one
of them in
your design:
I have HFD2 Subminiature DIP
Your FT-747 only has one antenna input. It does not have a second
receiver. It doesn't even have a receive-only antenna input. You cannot
transmit and receive at same time. Why do you need a front end saver?
It needs a preamp saver or a receiver antenna saver, not a front end saver.
Any old
Hi Douglas,
I am sorry to tell you that none of the relays you have is good for the
front end saver. They are usual small signal relays but a reed relay
should be used. The most important thing is not the capacitance (assumed
that the front end saver is used on 160, 80 and possibly 40 m), but
Doug -
Your FT-747 only has one antenna input. It does not have a second
receiver. It doesn't even have a receive-only antenna input. You cannot
transmit and receive at same time. Why do you need a front end saver?
If you are adding an outboard relay keyed from the amp control line of
the
: Tim Shoppa tsho...@gmail.com
Cc: topBand List topband@contesting.com
Sent: Saturday, August 29, 2015 3:05 PM
Subject: Re: Topband: KD9SV-OK1RR relays ???
Doug -
Your FT-747 only has one antenna input. It does not have a second
receiver. It doesn't even have a receive-only antenna input. You
Is there a reason to favor relays over taking a pin diode to ground to
short the input during tx?
Art NK8X
ᐧ
On Sat, Aug 29, 2015 at 2:31 PM, Martin Kratoska mar...@centrum.cz wrote:
Hi Douglas,
I am sorry to tell you that none of the relays you have is good for the
front end saver. They
It seems to me that a very fast operating preamp protection circuit could
be
constructed employing a good fast saturating NPN switching transistor
across
the antenna path. In receive mode the collector-base junction would have
substantial reverse bias and the transistor can be chosen for low
: KD9SV-OK1RR relays ???
Your FT-747 only has one antenna input. It does not have a second
receiver. It doesn't even have a receive-only antenna input. You cannot
transmit and receive at same time. Why do you need a front end saver?
It needs a preamp saver or a receiver antenna saver, not a front
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