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{ "url": "https://mailman.amsat.org/hyperkitty/api/list/[email protected]/email/B4LT3GQC6JWJTUFYDOXHILCAAGICDQX6/", "mailinglist": "https://mailman.amsat.org/hyperkitty/api/list/[email protected]/", "message_id": "CA+jqLCgnmwQDAM5i6ghmCnYUiYHgXoG8Q+G6XcZZ1CHNQVty5A@mail.gmail.com", "message_id_hash": "B4LT3GQC6JWJTUFYDOXHILCAAGICDQX6", "thread": "https://mailman.amsat.org/hyperkitty/api/list/[email protected]/thread/B4LT3GQC6JWJTUFYDOXHILCAAGICDQX6/", "sender": { "address": "vu3sxe (a) gmail.com", "mailman_id": "81c0806b1dcb485aa847e1e03da8a7de", "emails": "https://mailman.amsat.org/hyperkitty/api/sender/81c0806b1dcb485aa847e1e03da8a7de/emails/" }, "sender_name": "Sundeep Shah", "subject": "[AMSAT-BB] Leave", "date": "2022-12-29T06:27:03Z", "parent": null, "children": [], "votes": { "likes": 0, "dislikes": 0, "status": "neutral" }, "content": "Leave\n\nOn Thu, Dec 29, 2022, 2:22 AM Thomas Schuessler via AMSAT-BB <\[email protected]> wrote:\n\n> As I stated in a previous email, I use a diplexer as a filter in front of\n> the preamp to black out if band influence. For the 70 cm preamp I have a\n> duplexer that is only passing the 70 cm band from the 70 cm antenna into\n> the preamp. There is a similar duplexer feeding 2 meters only to the 2 m\n> antenna, and that after the 2 m preamp.\n>\n> I will probably try one of the SSB preamps, which have a higher power\n> rating than the ARR that I have in hopes that the increased margin of error\n> will cause things to hold up better.\n>\n> Sent from my iPhone\n>\n> On Dec 28, 2022, at 12:28, Paul Andrews <[email protected]> wrote:\n>\n> \n> The 70cm band is hamonically related to the 2m band.\n>\n> 2m into 70cm 3rd harmonic interference is more likely than 70cm into 2m.\n>\n> Happy New Year.\n>\n> 73 - Paul - W2HRO\n>\n> On Wed, Dec 28, 2022, 10:00 tjschuessler--- via AMSAT-BB <\n> [email protected]> wrote:\n>\n>> I do not believe it is RF from the 2 Meter transmit that is leaking into\n>> the antenna side, as I run a duplexer in front of the preamp input. 70 CM\n>> portion of arrow through a duplexer with only the 70 cm signal passing\n>> through that duplexer. I do the same on the 2 Meter side. This\n>> arrangement almost totally eliminates any de-sense of the RX on 70 CM from\n>> 2 M transmit.\n>>\n>>\n>>\n>> *From:* Paul Andrews <[email protected]>\n>> *Sent:* Tuesday, December 27, 2022 9:02 AM\n>> *To:* [email protected]\n>> *Cc:* AMSAT-BB <[email protected]>\n>> *Subject:* Re: [AMSAT-BB] UHF preamps\n>>\n>>\n>>\n>> Tom,\n>>\n>>\n>>\n>> Are you relying on the transmit RF sensing feature of this 432 MHz\n>> preamp? RF sensing can be unreliable. You might use the FT-847's RF amp\n>> enable output to trigger the external preamps.\n>>\n>>\n>>\n>> Another thought. It is possible that your 2m transmit signal is leaking\n>> into the input of the 70cm preamp. It's likely that significant coupling\n>> is occurring at the arrow antenna.\n>>\n>>\n>>\n>> You might consider using separate preamps and isolating relays.\n>>\n>>\n>>\n>> 73 - Paul - W2HRO\n>>\n>>\n>>\n>>\n>>\n>>\n>>\n>>\n>>\n>>\n>>\n>>\n>>\n>>\n>>\n>>\n>>\n>>\n>>\n>>\n>>\n>>\n>>\n>> On Mon, Dec 26, 2022 at 11:32 PM tjschuessler--- via AMSAT-BB <\n>> [email protected]> wrote:\n>>\n>> For my portable/temporary satellite antenna rig, I have need of using a\n>> UHF preamp, which I have strapped to the tripod that holds and aims my\n>> Arrow antenna. I find that my FT847 is just not as sensitive on 70 CM as\n>> it is on 2M. I have been using an ARR (Advanced Receiver Research )\n>> SP432VDG which is supposed to have a maximum power pass through imitation\n>> of 25watts. I try to be pretty careful as to how much output I run through\n>> the thing, maybe limiting to 15 watts or so. Unfortunately, I have blown\n>> the preamp out several times, even with being conscious of the RF level. I\n>> sent the pre to them, they repaired and sent back. I recently discovered\n>> that I had blown my unit again. Symptom is that it adds noise to the\n>> output, but does not amplify any signals coming into it from the antenna.\n>> I have sent the unit in to ARR in the past for repair. This time I am\n>> contemplating replacing this one with a more robust device that might be\n>> able to handle more RF running through it (RF sensing means you will still\n>> hit the device with an instantaneous burst of RF before the internal relays\n>> kick in.\n>>\n>>\n>>\n>> A friend has confided that he has the higher power version of the ARR\n>> Preamps, but has had similar problems with killing the things. Thus I am\n>> in the market for maybe another option. While I oft times, will stroll\n>> over to the antenna tripod, and barrel off the cables going to and from the\n>> preamp to bypass completely from the transmit chain, this is kind of a\n>> pain, even in a portable situation.\n>>\n>>\n>>\n>> I looked at M2s web site and can find a 2 Meter amp, but no 70CM (Might\n>> be missing something. I have heard a lot of good things on the SSB\n>> preamps, but the only pace I can see them being sold, is Dolstra in\n>> Europe. Don’t see a US vendor.\n>>\n>>\n>>\n>> Looking for suggestions. I would be interested in buying pre-owned, if\n>> someone had a Preamp that would like a new home.\n>>\n>>\n>>\n>> I do have a question for Yaesu FT847 users. With that radio, you can\n>> power a Preamp via the built in Bia- T power inserter, And assume that when\n>> this mode is turned on, it cuts the inserted DC to the preamp as the\n>> tranciever goes into transmit. Does this work fast enough to protect, even\n>> RF switched preamps? That might be a good safety measure as I have\n>> traditionally used external DC to power my preamps.\n>>\n>>\n>>\n>> Wisdom from the cloud here would be much appreciated.\n>>\n>> .\n>>\n>> Tom Schuessler, N5HYP\n>>\n>>\n>> -----------------------------------------------------------\n>>\n>> Sent via AMSAT-BB(a)amsat.org. AMSAT-NA makes this open forum available\n>> to all interested persons worldwide without requiring membership.\n>> Opinions expressed\n>> are solely those of the author, and do not reflect the official views of\n>> AMSAT-NA.\n>> Acceptable Use and Privacy Policies available at\n>> https://www.amsat.org/about-amsat/\n>>\n>> View archives of this mailing list at\n>> https://mailman.amsat.org/hyperkitty/list/[email protected]\n>> To unsubscribe send an email to amsat-bb-leave(a)amsat.org\n>> Manage all of your AMSAT-NA mailing list preferences at\n>> https://mailman.amsat.org\n>>\n>>\n>> -----------------------------------------------------------\n>>\n>> Sent via AMSAT-BB(a)amsat.org. AMSAT-NA makes this open forum available\n>> to all interested persons worldwide without requiring membership.\n>> Opinions expressed\n>> are solely those of the author, and do not reflect the official views of\n>> AMSAT-NA.\n>> Acceptable Use and Privacy Policies available at\n>> https://www.amsat.org/about-amsat/\n>>\n>> View archives of this mailing list at\n>> https://mailman.amsat.org/hyperkitty/list/[email protected]\n>> To unsubscribe send an email to amsat-bb-leave(a)amsat.org\n>> Manage all of your AMSAT-NA mailing list preferences at\n>> https://mailman.amsat.org\n>\n>\n> -----------------------------------------------------------\n>\n> Sent via AMSAT-BB(a)amsat.org. AMSAT-NA makes this open forum available\n> to all interested persons worldwide without requiring membership. Opinions\n> expressed\n> are solely those of the author, and do not reflect the official views of\n> AMSAT-NA.\n> Acceptable Use and Privacy Policies available at\n> https://www.amsat.org/about-amsat/\n>\n> View archives of this mailing list at\n> https://mailman.amsat.org/hyperkitty/list/[email protected]\n> To unsubscribe send an email to amsat-bb-leave(a)amsat.org\n> Manage all of your AMSAT-NA mailing list preferences at\n> https://mailman.amsat.org\n\n\n", "attachments": [ { "email": "https://mailman.amsat.org/hyperkitty/api/list/[email protected]/email/B4LT3GQC6JWJTUFYDOXHILCAAGICDQX6/", "counter": 2, "name": "attachment.html", "content_type": "text/html", "encoding": "utf-8", "size": 11699, "download": "https://mailman.amsat.org/hyperkitty/list/[email protected]/message/B4LT3GQC6JWJTUFYDOXHILCAAGICDQX6/attachment/2/attachment.html" } ] }