Return-Path: Received: from post.thorcom.com (post.thorcom.com [195.171.43.25]) by klubnl.pl (8.14.4/8.14.4/Debian-8+deb8u2) with ESMTP id w6AK7jKR032234 for ; Tue, 10 Jul 2018 22:07:48 +0200 Received: from majordom by post.thorcom.com with local (Exim 4.14) id 1fcyr7-0003Kb-Ml for rs_out_1@blacksheep.org; Tue, 10 Jul 2018 21:03:25 +0100 Received: from [195.171.43.32] (helo=relay1.thorcom.net) by post.thorcom.com with esmtp (Exim 4.14) id 1fcyr6-0003KS-Pe for rsgb_lf_group@blacksheep.org; Tue, 10 Jul 2018 21:03:24 +0100 Received: from mail-ed1-x529.google.com ([2a00:1450:4864:20::529]) by relay1.thorcom.net with esmtps (TLSv1.2:ECDHE-RSA-AES256-GCM-SHA384:256) (Exim 4.91_59-0488984) (envelope-from ) id 1fcyr4-0001yb-11 for rsgb_lf_group@blacksheep.org; Tue, 10 Jul 2018 21:03:23 +0100 Received: by mail-ed1-x529.google.com with SMTP id t2-v6so2857457edr.5 for ; Tue, 10 Jul 2018 13:03:21 -0700 (PDT) X-DKIM-Result: Domain=gmail.com Result=Good and Known Domain DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=mime-version:in-reply-to:references:from:date:message-id:subject:to; bh=8FvTPimXYfei5K2bsbc7tHlm3itT6jepczDHIq5kGFU=; b=hAin1/7tnxy2FkcuY2psh6fzcwxxkdK5vn4nlQY7SMvED/QZreQBoWJd8/VdRNVZEI bpH9GtK8IsY1wvXFu4G5v6ecukmAO6a1R3JkGoXZ7GeDzqJcfYFBqkLuTxPz6SjbR+Xt R6fVrwEcKBMGw8v+jby6lKAmwCeQRpVsMheU80tXrtdEKnKaqkAlcyRRkpQMvyBQiO86 js4gjgKrokJx//giCvlxEjDGTap8qVe3xqxJ8vDcsrCxqXN07/ZdKo0Es19esMKQmJXN OEnx+nxhdioQpacJJNOOb+bStsusiqIxY3PeFKJCcEYaVpjtnIA766QfhhviQ1TRsLPp Qy/w== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:in-reply-to:references:from:date :message-id:subject:to; bh=8FvTPimXYfei5K2bsbc7tHlm3itT6jepczDHIq5kGFU=; b=Ud0ThEQ7yGoJJEOp2uobSI3KNVbNabJ4omeRGucmAxGcsYSGdEPcCKChBnqYXDeA3G sbaX6qWdLOK3jIYLNrMVhH2KSO/sbUPq+Cn0fDSDyagpKJiuhuFv56w2zR12mXXO9Q2+ MtLMjX6j9Pq4vE1usWzYlrH4bAAQxo4kzObX4KHcU6xMYqROXRIp7LirSsNScCh1gwPA cCDixqNnJemlzb/+CmNKUZ0d27RWDsCn4rBfr5t3tVGQUVrAs2dnZ/zez4wV2bT5NHnG rIcDNegPq2Af+qo4TqffD6IUk4bz5JLh2LS71YNc3wJDoUhIv3l2v8BJ2jLkfne+p80M b9yQ== X-Gm-Message-State: APt69E05OumRM9MDc0VCZoKISv1DA9iTOgx4Wdd4HnD3rXyTpd+/wU/Q 8152c6gQlcV1vcqCP3tTlU3JJhGRY62G9K+r6UI= X-Google-Smtp-Source: AAOMgpeDVkY+a38BNpKF+djgsRZVT0KVaU4OGpHZzSVms9hb8xjHrEXAFdFmz0W+5nzJQG+u3qgKAzmhHdQOJqZVVaY= X-Received: by 2002:aa7:d1cb:: with SMTP id g11-v6mr27879686edp.163.1531253001153; Tue, 10 Jul 2018 13:03:21 -0700 (PDT) MIME-Version: 1.0 Received: by 2002:aa7:d6c4:0:0:0:0:0 with HTTP; Tue, 10 Jul 2018 13:03:20 -0700 (PDT) In-Reply-To: <28bc2416-8c3d-ae0b-f7e2-0579550c748f@n1bug.com> References: <09a39510-37a4-06dc-5fc8-05fe24d4e681@n1bug.com> <5B44A64A.1070307@posteo.de> <3d737f55-9e30-1c39-f34c-ea6f3c1c06af@n1bug.com> <5B44B5A4.6040401@posteo.de> <4eba6794-e366-5244-c9a8-621cc215da05@n1bug.com> <28bc2416-8c3d-ae0b-f7e2-0579550c748f@n1bug.com> From: Andy Talbot Date: Tue, 10 Jul 2018 21:03:20 +0100 Message-ID: To: LineOne X-Spam-Score: 0.0 (/) X-Spam-Report: Spam detection software, running on the system "relay1.thorcom.net", has NOT identified this incoming email as spam. The original message has been attached to this so you can view it or label similar future email. If you have any questions, see @@CONTACT_ADDRESS@@ for details. Content preview: The softrock is a stiff FET gate switch. designed for 3.3V digital busses running at hundreds of MHz. If the input exceeds the 0/3.3V rails, it'll just clamp to them. The opamps are ... well ... opamps, but they have an input series resistor the keep them safe [...] Content analysis details: (0.0 points, 5.0 required) pts rule name description ---- ---------------------- -------------------------------------------------- -0.0 RCVD_IN_DNSWL_NONE RBL: Sender listed at http://www.dnswl.org/, no trust [2a00:1450:4864:20:0:0:0:529 listed in] [list.dnswl.org] 0.0 FREEMAIL_FROM Sender email is commonly abused enduser mail provider (andy.g4jnt[at]gmail.com) -0.0 SPF_PASS SPF: sender matches SPF record 0.0 HTML_MESSAGE BODY: HTML included in message 0.0 T_DKIM_INVALID DKIM-Signature header exists but is not valid X-Scan-Signature: 81e655fcf3a8bdab256d37a53bc8dabb Subject: Re: LF: Receiver protection Content-Type: multipart/alternative; boundary="00000000000031ef8f0570aa9f3e" X-Spam-Checker-Version: SpamAssassin 2.63 (2004-01-11) on post.thorcom.com X-Spam-Level: X-Spam-Status: No, hits=0.0 required=5.0 tests=HTML_MESSAGE autolearn=no version=2.63 X-SA-Exim-Scanned: Yes Sender: owner-rsgb_lf_group@blacksheep.org Precedence: bulk Reply-To: rsgb_lf_group@blacksheep.org X-Listname: rsgb_lf_group X-SA-Exim-Rcpt-To: rs_out_1@blacksheep.org X-SA-Exim-Scanned: No; SAEximRunCond expanded to false --00000000000031ef8f0570aa9f3e Content-Type: text/plain; charset="UTF-8" The softrock is a stiff FET gate switch. designed for 3.3V digital busses running at hundreds of MHz. If the input exceeds the 0/3.3V rails, it'll just clamp to them. The opamps are ... well ... opamps, but they have an input series resistor the keep them safe You'd have to try pretty hard to destroy a Softrock Andy www.g4jnt.com On 10 July 2018 at 20:47, N1BUG wrote: > Hi Andy, > > It is the Softrock I am concerned about. I don't know what the > FST3253 can handle but I don't fancy replacing them if something > were to happen. > > I tried putting the diodes at the output of the preamp but that > didn't work. After a TX cycle, the preamp had to be powered off and > back on to get things working again. So I reluctantly moved the > diodes to the input where I have had no further trouble. > > As you say, +5 dBm input to a 2N5109 is likely to be +25 dBm output > which worries me going into the FST3253. > > 73, > Paul > > > On 07/10/2018 03:19 PM, Andy Talbot wrote: > > That preamp looks as if it would laugh at +5dB input and just > > amplify it linearly - giving your Softrocka run for itsmoney. > > > > A can see that preamp easily surviving well over +20dBm input > > leakage. Its dissipating something like 1 Watt in its own right, so > > you can quite reasoably to expect it to be happy with even that sort > > of input. > > > > So you could even contemplate pairs of series diodes to limit at a > > HIGHER voltage and that way less of a compromise on strong signal > > handling that input diodes always give you. > > > > Mind you , on my 400W 475kHz Class-E amp, I do use a pair of relays, > > terminating Rx in 50 ohms and measure 70dB attenuation. But I do > > run Rx into an SDR-IQ which is a bit more expensive to replace. But > > even that can survive over +20dBm. I know, I've done it! > > > > Andy > > www.g4jnt.com > > > > > > On 10 July 2018 at 20:03, N1BUG > > wrote: > > > > Hi Stefan, > > > > > I suggest to discuss along a concrete schematic that you could > > present > > > along with the question(s). > > > > Here is a simplified description of the setup. RX antenna (at the > > moment, but soon to change or have more than one choice) > > > > http://www.n1bug.com/lnv.jpg > > > > Then there is a two way splitter. One output feeds the LF RX system: > > band pass filter, preamp, band pass filter, receiver. The other > > output has the same line up but for MF. > > > > The preamps, with diodes added at the input > > > > http://www.n1bug.com/w1vd-pre2.png > > > > > > Finally the receivers (one for LF, one for MF) > > > > http://www.n1bug.com/srlite2.png > > > > These receivers may look too simple but with the filters and preamps > > have done quite well for me! > > > > I was hoping for something better than the diodes to put there at > > the preamp input. Something which would limit to a much lower level. > > > > For HF, a company called ICE used to make RX protectors (ICE-196) > > which use some kind of very small transformer on a ferrite core. I > > think the idea was the core saturates to provide limiting. But there > > were other parts, including diodes, resistor, capacitor. I have two > > of these, one is permanently connected to the RX antenna input on my > > FT-2000 transceiver. Unfortunately these do not work below 1 MHz. > > The insertion loss becomes very high at MF and LF. > > > > Probably the best, as many people have said, is to give up this > > silly idea of limiting at the RX front end and use a fast relay to > > disconnect RX antenna and put instead 50 ohm resistor on RX input. > > This we can say is quite safe for the receiver. :-) > > > > It's just some work. I have a FT-2000 which I use with home built > > down converters for CW and digital QSOs on MF and LF. I think there > > is 15 ms between FT-2000 PTT output going low and the beginning of > > RF output, so with a fast relay it should be OK. > > > > I also have a Ultimate 3S beacon transmitter. It provides +5V output > > for external T/R switching, supposedly with a programmable delay. I > > have it set to 50 ms now. I am sorry to say I do not completely > > trust this as there are some things which do not work quite as they > > should with this device. I don't know if the T/R delay is correct > > and reliable. I will try to measure it. > > > > The FT-2000 and all LF/MF receiving stuff is in one room, the ham > > shack. MF and LF down converters, amplifiers, and U3S are in another > > room, the lab or work shop. There was no more space in the ham > > shack. ;-) It's really quite silly to call that little room the lab > > or shop, because there is a ongoing radio construction project in > > every room of my house! The whole place is a work shop! > > > > Some time in the future I may be able to use my HP 3325B synthesizer > > with a linear PA to TX Ebnaut. I don't have any idea how I will > > provide proper timing to switch the RX input relay with that, but I > > will worry about it later. > > > > For now I think I should just make the decision and do the work to > > make both the FT-2000 and the U3S (if its T/R delay is reliable) to > > switch a relay disconnecting the RX antenna during TX. Unless > > somebody has a better idea about serious limiting at the RX... > > > > >> I need to stop being lazy. ;-) > > >> > > > Oh oh, i know what you mean. Good point :-) I can observe the > > same > > > behaviour here. Sitting in front of the monitor, watching > > grabbers, > > > watching the WSPR map, programming some Linux stuff, playing with > > > SpecLab can be quite comfortable and relaxing. When looking > > back, 10 > > > years ago i have been more spontaneous in doing portable > > experiments. > > > But can this tendency be stopped or is it hopeless? It could > > be helpful > > > to analyse the causes instead of 'fighting' against oneselve. > > > > Sounds like fun! I'm a little bit tired from building. I built all > > the LF and MF RX stuff including receivers, preamps, many filters, > > splitters and so on. I built the U3S, TX converters, TX antenna, > > variometers, transformers. I built a few LF and MF PAs before > > finding success... and success came after many weeks of tracking > > down trouble. Now I'm just finishing up the build of a power supply > > for the new LF PA, also doing a lot of work to make new and better > > cables to connect all this stuff together. I enjoy building stuff, > > but I am ready for a little break. All this has been a bit of a rush > > trying to get it all done as quickly as possible. After I finish the > > power supply, RX protection, and new RX antenna maybe I can rest and > > do some operating... ;-) > > > > 73, > > Paul > > --00000000000031ef8f0570aa9f3e Content-Type: text/html; charset="UTF-8" Content-Transfer-Encoding: quoted-printable
The softrock is a stiff FET gate switch. designed for 3.3V= digital busses running at hundreds of MHz.=C2=A0 =C2=A0 If the input excee= ds the 0/3.3V rails, it'll just clamp to them.=C2=A0 The opamps are ...= well ... opamps, but they have an input series resistor the keep them safe=

You'd have to try pretty hard to destroy a Softrock=


On 10 July 2018 at 20:47, N1BUG <paul@n1bug.co= m> wrote:
Hi Andy,

It is the Softrock I am concerned about. I don't know what the
FST3253 can handle but I don't fancy replacing them if something
were to happen.

I tried putting the diodes at the output of the preamp but that
didn't work. After a TX cycle, the preamp had to be powered off and
back on to get things working again. So I reluctantly moved the
diodes to the input where I have had no further trouble.

As you say, +5 dBm input to a 2N5109 is likely to be +25 dBm output
which worries me going into the FST3253.

73,
Paul


On 07/10/2018 03:19 PM, Andy Talbot wrote:
> That preamp looks as if it would laugh at +5dB input and just
> amplify it linearly - giving your Softrocka=C2=A0 run for itsmoney. >
> A=C2=A0 can see that preamp=C2=A0 easily surviving well over +20dBm in= put
> leakage.=C2=A0 Its dissipating something like 1 Watt in its own right,= so
> you can quite reasoably to expect it to be happy with even that sort > of input.
>
> So you could even contemplate pairs of series diodes to limit at a
> HIGHER voltage and that way less of a compromise on strong signal
> handling that input diodes always give you.
>
> Mind you , on my 400W 475kHz Class-E amp, I do use a pair of relays, > terminating Rx in 50 ohms and measure 70dB attenuation.=C2=A0 But I do=
> run Rx into an SDR-IQ which is a bit more expensive to replace.=C2=A0 = But
> even that can survive over +20dBm.=C2=A0 I know, I've done it!
>
> Andy
> www.g4jnt.com <http://www.g4jnt.com>
>
>
> On 10 July 2018 at 20:03, N1BUG <= paul@n1bug.com
> <mailto:p= aul@n1bug.com>> wrote:
>
>=C2=A0 =C2=A0 =C2=A0Hi Stefan,
>
>=C2=A0 =C2=A0 =C2=A0> I suggest to discuss along a concrete schemati= c that you could
>=C2=A0 =C2=A0 =C2=A0present
>=C2=A0 =C2=A0 =C2=A0> along with the question(s).
>
>=C2=A0 =C2=A0 =C2=A0Here is a simplified description of the setup. RX a= ntenna (at the
>=C2=A0 =C2=A0 =C2=A0moment, but soon to change or have more than one ch= oice)
>
>=C2=A0 =C2=A0 =C2=A0http://www.n1bug.com/lnv.jpg
>
>=C2=A0 =C2=A0 =C2=A0Then there is a two way splitter. One output feeds = the LF RX system:
>=C2=A0 =C2=A0 =C2=A0band pass filter, preamp, band pass filter, receive= r. The other
>=C2=A0 =C2=A0 =C2=A0output has the same line up but for MF.
>
>=C2=A0 =C2=A0 =C2=A0The preamps, with diodes added at the input
>
>=C2=A0 =C2=A0 =C2=A0http://www.n1bug.com/w1vd-pre2.png
>=C2=A0 =C2=A0 =C2=A0<http://www.n1bug.com/w1vd-pre2.pn= g>
>
>=C2=A0 =C2=A0 =C2=A0Finally the receivers (one for LF, one for MF)
>
>=C2=A0 =C2=A0 =C2=A0http://www.n1bug.com/srlite2.png= <http://www.n1bug.com/srlite2.png>
>
>=C2=A0 =C2=A0 =C2=A0These receivers may look too simple but with the fi= lters and preamps
>=C2=A0 =C2=A0 =C2=A0have done quite well for me!
>
>=C2=A0 =C2=A0 =C2=A0I was hoping for something better than the diodes t= o put there at
>=C2=A0 =C2=A0 =C2=A0the preamp input. Something which would limit to a = much lower level.
>
>=C2=A0 =C2=A0 =C2=A0For HF, a company called ICE used to make RX protec= tors (ICE-196)
>=C2=A0 =C2=A0 =C2=A0which use some kind of very small transformer on a = ferrite core. I
>=C2=A0 =C2=A0 =C2=A0think the idea was the core saturates to provide li= miting. But there
>=C2=A0 =C2=A0 =C2=A0were other parts, including diodes, resistor, capac= itor. I have two
>=C2=A0 =C2=A0 =C2=A0of these, one is permanently connected to the RX an= tenna input on my
>=C2=A0 =C2=A0 =C2=A0FT-2000 transceiver. Unfortunately these do not wor= k below 1 MHz.
>=C2=A0 =C2=A0 =C2=A0The insertion loss becomes very high at MF and LF.<= br> >
>=C2=A0 =C2=A0 =C2=A0Probably the best, as many people have said, is to = give up this
>=C2=A0 =C2=A0 =C2=A0silly idea of limiting at the RX front end and use = a fast relay to
>=C2=A0 =C2=A0 =C2=A0disconnect RX antenna and put instead 50 ohm resist= or on RX input.
>=C2=A0 =C2=A0 =C2=A0This we can say is quite safe for the receiver. :-)=
>
>=C2=A0 =C2=A0 =C2=A0It's just some work. I have a FT-2000 which I u= se with home built
>=C2=A0 =C2=A0 =C2=A0down converters for CW and digital QSOs on MF and L= F. I think there
>=C2=A0 =C2=A0 =C2=A0is 15 ms between FT-2000 PTT output going low and t= he beginning of
>=C2=A0 =C2=A0 =C2=A0RF output, so with a fast relay it should be OK. >
>=C2=A0 =C2=A0 =C2=A0I also have a Ultimate 3S beacon transmitter. It pr= ovides +5V output
>=C2=A0 =C2=A0 =C2=A0for external T/R switching, supposedly with a progr= ammable delay. I
>=C2=A0 =C2=A0 =C2=A0have it set to 50 ms now. I am sorry to say I do no= t completely
>=C2=A0 =C2=A0 =C2=A0trust this as there are some things which do not wo= rk quite as they
>=C2=A0 =C2=A0 =C2=A0should with this device. I don't know if the T/= R delay is correct
>=C2=A0 =C2=A0 =C2=A0and reliable. I will try to measure it.
>
>=C2=A0 =C2=A0 =C2=A0The FT-2000 and all LF/MF receiving stuff is in one= room, the ham
>=C2=A0 =C2=A0 =C2=A0shack. MF and LF down converters, amplifiers, and U= 3S are in another
>=C2=A0 =C2=A0 =C2=A0room, the lab or work shop. There was no more space= in the ham
>=C2=A0 =C2=A0 =C2=A0shack. ;-) It's really quite silly to call that= little room the lab
>=C2=A0 =C2=A0 =C2=A0or shop, because there is a ongoing radio construct= ion project in
>=C2=A0 =C2=A0 =C2=A0every room of my house! The whole place is a work s= hop!
>
>=C2=A0 =C2=A0 =C2=A0Some time in the future I may be able to use my HP = 3325B synthesizer
>=C2=A0 =C2=A0 =C2=A0with a linear PA to TX Ebnaut. I don't have any= idea how I will
>=C2=A0 =C2=A0 =C2=A0provide proper timing to switch the RX input relay = with that, but=C2=A0 I
>=C2=A0 =C2=A0 =C2=A0will worry about it later.
>
>=C2=A0 =C2=A0 =C2=A0For now I think I should just make the decision and= do the work to
>=C2=A0 =C2=A0 =C2=A0make both the FT-2000 and the U3S (if its T/R delay= is reliable) to
>=C2=A0 =C2=A0 =C2=A0switch a relay disconnecting the RX antenna during = TX. Unless
>=C2=A0 =C2=A0 =C2=A0somebody has a better idea about serious limiting a= t the RX...
>
>=C2=A0 =C2=A0 =C2=A0>> I need to stop being lazy. ;-)
>=C2=A0 =C2=A0 =C2=A0>>=C2=A0 =C2=A0
>=C2=A0 =C2=A0 =C2=A0> Oh oh, i know what you mean. Good point :-) I = can observe the
>=C2=A0 =C2=A0 =C2=A0same
>=C2=A0 =C2=A0 =C2=A0> behaviour here. Sitting in front of the monito= r, watching
>=C2=A0 =C2=A0 =C2=A0grabbers,
>=C2=A0 =C2=A0 =C2=A0> watching the WSPR map, programming some Linux = stuff, playing with
>=C2=A0 =C2=A0 =C2=A0> SpecLab can be quite comfortable and relaxing.= When looking
>=C2=A0 =C2=A0 =C2=A0back, 10
>=C2=A0 =C2=A0 =C2=A0> years ago i have been more spontaneous in doin= g portable
>=C2=A0 =C2=A0 =C2=A0experiments.
>=C2=A0 =C2=A0 =C2=A0> But can this tendency be stopped or is it hope= less? It could
>=C2=A0 =C2=A0 =C2=A0be helpful
>=C2=A0 =C2=A0 =C2=A0> to analyse the causes instead of 'fighting= ' against oneselve.
>
>=C2=A0 =C2=A0 =C2=A0Sounds like fun! I'm a little bit tired from bu= ilding. I built all
>=C2=A0 =C2=A0 =C2=A0the LF and MF RX stuff including receivers, preamps= , many filters,
>=C2=A0 =C2=A0 =C2=A0splitters and so on. I built the U3S, TX converters= , TX antenna,
>=C2=A0 =C2=A0 =C2=A0variometers, transformers. I built a few LF and MF = PAs before
>=C2=A0 =C2=A0 =C2=A0finding success... and success came after many week= s of tracking
>=C2=A0 =C2=A0 =C2=A0down trouble. Now I'm just finishing up the bui= ld of a power supply
>=C2=A0 =C2=A0 =C2=A0for the new LF PA, also doing a lot of work to make= new and better
>=C2=A0 =C2=A0 =C2=A0cables to connect all this stuff together. I enjoy = building stuff,
>=C2=A0 =C2=A0 =C2=A0but I am ready for a little break. All this has bee= n a bit of a rush
>=C2=A0 =C2=A0 =C2=A0trying to get it all done as quickly as possible. A= fter I finish the
>=C2=A0 =C2=A0 =C2=A0power supply, RX protection, and new RX antenna may= be I can rest and
>=C2=A0 =C2=A0 =C2=A0do some operating... ;-)
>
>=C2=A0 =C2=A0 =C2=A073,
>=C2=A0 =C2=A0 =C2=A0Paul


--00000000000031ef8f0570aa9f3e--