Hi as a newcomer to this part of the hobby I have a couple of questions.
1. When using the M2 egg beaters how important is it to install a masthead preamplifier?
2. Again with egg beater will 30 watts be enough to get back to the bird?
I am using about 80 feet of RG213 to connect the antenna.
Many thanks
Roger G0AWY
73
Hi Roger,
Well RG213 isn't your optimal choice of cable. For example it has a loss that is about twice as high as similar sized LMR400, and that really has an impact on 70 cm. At 80 feet you are losing well over half your TX power -- your 30 watts into the coax will turn into about 12 watts at the antenna. At that distance LMR600 is probably worth it.
I've used a pair of M2 Eggbeaters since 1998, so they have been up 20 years now. I do use a SSB Electronics mast-mounted preamp on each. My lengths are 50 feet for 70 cm, and 75 feet for 2 meters. I run 50 watts. Generally I have no problem making a few contacts each pass. Things work well for about 1/3 of the pass, and fair for another 1/3 of the pass, and not at all for 1/3 of the pass. In other words, you aren't going to be working stations down at the horizon, but you will be working stations when the satellite is closest to you and higher in the sky.
In my case I probably didn't need the mast mounted preamp as my cable loss was fairly low. In your case you are losing around 4 dB in your coax (for a mode VU bird). You can probably do without the preamp.
73, Bob, WB4SON
On Thu, Jul 19, 2018 at 6:41 AM, Roger Titmuss [email protected] wrote:
Hi as a newcomer to this part of the hobby I have a couple of questions.
- When using the M2 egg beaters how important is it to install a masthead
preamplifier?
- Again with egg beater will 30 watts be enough to get back to the bird?
I am using about 80 feet of RG213 to connect the antenna.
Many thanks
Roger G0AWY
73
Sent via [email protected]. AMSAT-NA makes this open forum available to all interested persons worldwide without requiring membership. Opinions expressed are solely those of the author, and do not reflect the official views of AMSAT-NA. Not an AMSAT-NA member? Join now to support the amateur satellite program! Subscription settings: http://www.amsat.org/mailman/listinfo/amsat-bb
You should read yesterday's thread on egg beaters on the qrz.com forums. One response said that today's birds don't have strong enough downlinks to work the birds well using egg beaters.
They will probably work for high elevation passes but they aren't recommended today in general. Seems like good info to me.
Preamps seem like an important component to use with egg beaters. Most folks using yagis use them too so they would be even more important with egg beaters.
https://forums.qrz.com/index.php?threads/egg-beater-antenna-question.620911/
73, John Brier KG4AKV
On Thu, Jul 19, 2018, 07:17 Roger Titmuss [email protected] wrote:
Hi as a newcomer to this part of the hobby I have a couple of questions.
- When using the M2 egg beaters how important is it to install a masthead
preamplifier?
- Again with egg beater will 30 watts be enough to get back to the bird?
I am using about 80 feet of RG213 to connect the antenna.
Many thanks
Roger G0AWY
73
Sent via [email protected]. AMSAT-NA makes this open forum available to all interested persons worldwide without requiring membership. Opinions expressed are solely those of the author, and do not reflect the official views of AMSAT-NA. Not an AMSAT-NA member? Join now to support the amateur satellite program! Subscription settings: http://www.amsat.org/mailman/listinfo/amsat-bb
Damn, those eggbeaters are expensive! On 19 Jul 2018, 14:17 +0100, Roger Titmuss [email protected], wrote:
Hi as a newcomer to this part of the hobby I have a couple of questions.
- When using the M2 egg beaters how important is it to install a masthead
preamplifier?
- Again with egg beater will 30 watts be enough to get back to the bird?
I am using about 80 feet of RG213 to connect the antenna.
Many thanks
Roger G0AWY
73
Sent via [email protected]. AMSAT-NA makes this open forum available to all interested persons worldwide without requiring membership. Opinions expressed are solely those of the author, and do not reflect the official views of AMSAT-NA. Not an AMSAT-NA member? Join now to support the amateur satellite program! Subscription settings: http://www.amsat.org/mailman/listinfo/amsat-bb
Roger asked:
- When using the M2 egg beaters how important is it to install a masthead
preamplifier?
OK, here is my opinion. Eggbeaters - or any other omni type antenna are only slightly above worthless. Uplink is not really a problem as you can always add power to make up for a poor antenna, but downlink IS a problem because once signal is lost, you can't make it back up. So yes, unless you have an extremely short coax run, I highly recommend a pre-amp at the antenna.
As has been commented many times on the BB, the vast majority of amateur satellite operation is weak signal. Too often new operators try to treat the FM satellites just like a repeater. That's fine if your repeater is 2,000 miles away and only transmitting a quarter watt. It's NOT! It is a weak signal. For people operating terrestrial weak signal, NO ONE would consider using a quarter wave ground plane antenna, but for some reason, so many people try to do essentially just that for satellite. It does not work well.
- Again with egg beater will 30 watts be enough to get back to the bird?
For the LEO satellites, that is plenty (or more than plenty in many cases).
I am using about 80 feet of RG213 to connect the antenna.
As someone else already pointed out, that is not overly good coax, so that makes a good low noise pre-amp AT the antenna even more important.
Disclaimer: Essentially all of my satellite operation has been voice - either FM or preferably SSB on the linear birds. I have no experience with some of the newer "weak signal" digital modes that can dig signals out that are at or below the noise floor. I have operated as a telemetry downlink station for the first USNA satellite which was using one of several omni designs, and worked like crap. For the record, I also operated some SSTV and Hellschreiber (Feld Hell) via AO-40 during it's short life :( At home I ran an AO-10 class antenna system: http://members.dslextreme.com/users/k6ccc/Photo/Pics/SatAnt1.html http://members.dslextreme.com/users/k6ccc/Photo/Pics/S-band1.html
Even mobile (special event) I ran yagis and El/Az rotors in my truck: http://members.dslextreme.com/users/k6ccc/Photo/Pics/MobileSat2.html
73 ----- Jim Walls - K6CCC [email protected]
On 07/19/18 11:12, [email protected] wrote:
So yes, unless you have an extremely short coax run, I highly recommend a pre-amp at the antenna.
Agreed! You can even build one of your own, if you're careful not to transmit through it.
Zach Metzinger wrote:
If you're looking for a shoestring-budget LNA for 2m, the U310 JFET preamp has been a good performer for me.
http://www.ham-radio.com/n6ca/50MHz/50appnotes/U310.html
I've constructed one in a spare project box, and the gain (12dB) is right on the predicted value. I have not verified the NF, but it is claimed to be near 1.0dB. I built in in one evening, with some extra evenings diagnosing a capacitor issue. Use a multi-turn piston trimmer for the 1-10pF drain capacitor, as the output tuning is very sharp.
I've changed the layout a bit, but here's an early picture of the unit:
The air-core inductors are not difficult to wind on a 1/4" drill bit.
Not as fancy as a GaAsFET or pHEMT device, but it works just fine to hear AO-85 and AO-7 with a non-ideal satellite antenna (folded horizontal dipole) at 10 degrees above the horizon.
On the subject of rotators, don't discount the SatNOGS rotator. I've built a version 2 with a total expenditure of < $100. It will not stand up to the elements, but I have plans to mount it in the attic.
--- Zach N0ZGO
Roger,
Just to share experience, in spite none with the M2 egg beaters.
1) 3B8FA and myself did many QSO with simple antenna such as egg beaters on many birds or other type of omni circular polarization antenna. We started with these and then moved to directional antennas which surely have many advantages but I suggest that you start with home brew antenna instead of buying expensive omni one as same may be build at home for a few $ with material available in any hardware store, more plenty of designs available on the net. 2) Contacts have been made with even verticals both sides here. 2) On VHF RX preamplifiers are not really needed (even with omni’s) for many birds, such as AO-91, AO-92, XW-2x series, CAS 4B. TX, 30W is more than enough for the birds mentioned in spite of you long coax. I had 30m RG213 with omni's which worked ok for many birds. 3) On UHF RX, you will probably need a preamp as your feeder quite long, but it may work out with FO-29 which is generally quite strong.
In a nutshell, don’t invest much money for omni antenna as after a while, if you get the virus, you will surely want to move to directional ones, keep the $ for these as the setup is not cheap. Learn the basic with cheap home brew antennas first that decide of what you need for the next frontier and save you $ for same.
Hope it helps.
Jean Marc (3B8DU)
On Jul 19, 2018, at 2:41 PM, Roger Titmuss [email protected] wrote:
Hi as a newcomer to this part of the hobby I have a couple of questions.
- When using the M2 egg beaters how important is it to install a masthead
preamplifier?
- Again with egg beater will 30 watts be enough to get back to the bird?
I am using about 80 feet of RG213 to connect the antenna.
Many thanks
Roger G0AWY
73
Sent via [email protected]. AMSAT-NA makes this open forum available to all interested persons worldwide without requiring membership. Opinions expressed are solely those of the author, and do not reflect the official views of AMSAT-NA. Not an AMSAT-NA member? Join now to support the amateur satellite program! Subscription settings: http://www.amsat.org/mailman/listinfo/amsat-bb
While I'm still new to the sats I have been doing VHF/UHF weak signal work since the 80's and I've always preferred to spend the money on feedline rather than pre-amps. Given that pre-amps amplify the rx noise and signal you really don't improve signal to noise unless the noise figure of the pre-amp is better than your receiver. Usually your just amplifying the signal to make up for the loss that's going to happen as the signal makes it's way down the coax.
You also add complexity when you want to TX on the antenna since you will need to add a t/r relay at the antenna. In addition, you are still losing tx power with the higher loss cable so depending on your ERP goal you may need an amplifier, generally not an issue with the LEO's. LMR-600 or hardline is my feedline of choice for 2m and up. I'm not suggesting that pre-amps can't or shouldn't be used but usually aren't needed if good low loss feedline is used to begin with.
Dave N2OA
On Thu, Jul 19, 2018 at 9:17 AM Roger Titmuss [email protected] wrote:
Hi as a newcomer to this part of the hobby I have a couple of questions.
- When using the M2 egg beaters how important is it to install a masthead
preamplifier?
- Again with egg beater will 30 watts be enough to get back to the bird?
I am using about 80 feet of RG213 to connect the antenna.
Many thanks
Roger G0AWY
73
Sent via [email protected]. AMSAT-NA makes this open forum available to all interested persons worldwide without requiring membership. Opinions expressed are solely those of the author, and do not reflect the official views of AMSAT-NA. Not an AMSAT-NA member? Join now to support the amateur satellite program! Subscription settings: http://www.amsat.org/mailman/listinfo/amsat-bb
On 07/19/18 12:17, Dave . wrote:
While I'm still new to the sats I have been doing VHF/UHF weak signal work since the 80's and I've always preferred to spend the money on feedline rather than pre-amps. Given that pre-amps amplify the rx noise and signal you really don't improve signal to noise unless the noise figure of the pre-amp is better than your receiver. Usually your just amplifying the signal to make up for the loss that's going to happen as the signal makes it's way down the coax.
Hello Dave,
With respect, your understanding of the problem is quite incorrect.
You should definitely "set" the noise figure of your receive system as early as possible with a LNA. Any decent LNA will have a noise figure far lower than your receiver, not to mention to the coax attenuation adding _directly_ to the NF of your system.
I used the data here:
http://www.df9ic.de/tech/trxtest/trxtest.html
Let's pick the IC910H, with a 3.7dB NF. Now, add 100' of LMR400 for a loss of 1.5dB at 2m. You end up with a NF of 5.2dB.
Next, let's try a LNA before that coax with a measly 1dB NF and 15dB of gain: NF of 1.325dB at the receiver.
https://www.pasternack.com/t-calculator-noise-figure.aspx
This can easily be seen with the Friis noise equation. Here's a good explanation with the (simple) math:
https://www.microwaves101.com/encyclopedias/noise-figure
I'd invest in a good LNA at the antenna and a PA in the shack before I'd ever think about upgrading my coax.
--- Zach N0ZGO
Hi Dave, You said everything I have learned and observed up until now, but please allow me to add one complication to it -
FM discriminators (aka de-modulators) cannot handle very low signals well, for example, the downlinks of older lower power birds. I observe this when I switch between a vertical and a Yagi, the extra signal strength from even a short 3 element Yagi keeps the FM discriminator very happy.
I find this issue less noticeable in SSB modes and adding a preamp is almost as good as turning up the volume control at the radio.
73! Umesh k6vug
On Thursday, July 19, 2018, 12:07:26 PM PDT, Dave . [email protected] wrote:
While I'm still new to the sats I have been doing VHF/UHF weak signal work since the 80's and I've always preferred to spend the money on feedline rather than pre-amps. Given that pre-amps amplify the rx noise and signal you really don't improve signal to noise unless the noise figure of the pre-amp is better than your receiver. Usually your just amplifying the signal to make up for the loss that's going to happen as the signal makes it's way down the coax.
You also add complexity when you want to TX on the antenna since you will need to add a t/r relay at the antenna. In addition, you are still losing tx power with the higher loss cable so depending on your ERP goal you may need an amplifier, generally not an issue with the LEO's. LMR-600 or hardline is my feedline of choice for 2m and up. I'm not suggesting that pre-amps can't or shouldn't be used but usually aren't needed if good low loss feedline is used to begin with.
Dave N2OA
On Thu, Jul 19, 2018 at 9:17 AM Roger Titmuss [email protected] wrote:
Hi as a newcomer to this part of the hobby I have a couple of questions.
- When using the M2 egg beaters how important is it to install a masthead
preamplifier?
- Again with egg beater will 30 watts be enough to get back to the bird?
I am using about 80 feet of RG213 to connect the antenna.
Many thanks
Roger G0AWY
73
Sent via [email protected]. AMSAT-NA makes this open forum available to all interested persons worldwide without requiring membership. Opinions expressed are solely those of the author, and do not reflect the official views of AMSAT-NA. Not an AMSAT-NA member? Join now to support the amateur satellite program! Subscription settings: http://www.amsat.org/mailman/listinfo/amsat-bb
_______________________________________________ Sent via [email protected]. AMSAT-NA makes this open forum available to all interested persons worldwide without requiring membership. Opinions expressed are solely those of the author, and do not reflect the official views of AMSAT-NA. Not an AMSAT-NA member? Join now to support the amateur satellite program! Subscription settings: http://www.amsat.org/mailman/listinfo/amsat-bb
In the commercial satcom industry an ODU use is common enough that one might ne able to purchase old ODU (outdoor units) with tight seals and a world of RF components and mixer stages for dirt cheap to several hundred watts and very small sensitivity parts in the receive chains. Of course they are in the wrong band but internal microwave shielded enclosures and bulletproof clean power supplies along with a LNA or LNB might interest some. My wish is to setup a station in DC using this method for ham sats. Has anyone alreday done this ? Hint .. old Anacom units. Plus it can and was designed to be integrated into high wind antenna structures. HPA sections can be uncoupled and replaced (I fixed them in remote sites) and replaced with ham sat stuff. Comments welcome.
Samudra N3RDX
Sent from a device with a small screen.
On Thu, Jul 19, 2018 at 4:13 PM -0400, "[email protected]" <[email protected]mailto:[email protected]> wrote:
Hi Dave, You said everything I have learned and observed up until now, but please allow me to add one complication to it -
FM discriminators (aka de-modulators) cannot handle very low signals well, for example, the downlinks of older lower power birds. I observe this when I switch between a vertical and a Yagi, the extra signal strength from even a short 3 element Yagi keeps the FM discriminator very happy.
I find this issue less noticeable in SSB modes and adding a preamp is almost as good as turning up the volume control at the radio.
73! Umesh k6vug
On Thursday, July 19, 2018, 12:07:26 PM PDT, Dave . wrote:
While I'm still new to the sats I have been doing VHF/UHF weak signal work since the 80's and I've always preferred to spend the money on feedline rather than pre-amps. Given that pre-amps amplify the rx noise and signal you really don't improve signal to noise unless the noise figure of the pre-amp is better than your receiver. Usually your just amplifying the signal to make up for the loss that's going to happen as the signal makes it's way down the coax.
You also add complexity when you want to TX on the antenna since you will need to add a t/r relay at the antenna. In addition, you are still losing tx power with the higher loss cable so depending on your ERP goal you may need an amplifier, generally not an issue with the LEO's. LMR-600 or hardline is my feedline of choice for 2m and up. I'm not suggesting that pre-amps can't or shouldn't be used but usually aren't needed if good low loss feedline is used to begin with.
Dave N2OA
On Thu, Jul 19, 2018 at 9:17 AM Roger Titmuss wrote:
Hi as a newcomer to this part of the hobby I have a couple of questions.
- When using the M2 egg beaters how important is it to install a masthead
preamplifier?
- Again with egg beater will 30 watts be enough to get back to the bird?
I am using about 80 feet of RG213 to connect the antenna.
Many thanks
Roger G0AWY
73
Sent via [email protected]. AMSAT-NA makes this open forum available to all interested persons worldwide without requiring membership. Opinions expressed are solely those of the author, and do not reflect the official views of AMSAT-NA. Not an AMSAT-NA member? Join now to support the amateur satellite program! Subscription settings: http://www.amsat.org/mailman/listinfo/amsat-bb
_______________________________________________ Sent via [email protected]. AMSAT-NA makes this open forum available to all interested persons worldwide without requiring membership. Opinions expressed are solely those of the author, and do not reflect the official views of AMSAT-NA. Not an AMSAT-NA member? Join now to support the amateur satellite program! Subscription settings: http://www.amsat.org/mailman/listinfo/amsat-bb
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The information contained in this communication is confidential, may be privileged and is intended for the exclusive use of the above named addressee(s). If you are not the intended recipient(s), you are expressly prohibited from copying, distributing, disseminating, or in any other way using any information contained within this communication. If you have received this communication in error please contact the sender by telephone or by response via mail. We have taken precautions to minimize the risk of transmitting software viruses, but we advise you to carry out your own virus checks on any attachment to this message. We cannot accept liability for any loss or damage caused by software viruses.
Sorry, should have added, the modems used in the commercial sat systems are IF-band (typ. 70 MHz center frequency +/- 18 MHz, or 140 MHz CF +/-) so any amateur radio service setup would have to consider how to get the modem generating low power RF to the ODU which would contain the transmit/receive switching (or separate TX and RX chains) and necessary high power amps and low noise amps respectively.
-----Original Message----- From: AMSAT-BB [mailto:[email protected]] On Behalf Of Samudra Haque [TTLLC] Sent: Friday, July 20, 2018 3:19 PM To: Dave . [email protected]; [email protected] Cc: [email protected] Subject: Re: [amsat-bb] Cables loss
In the commercial satcom industry an ODU use is common enough that one might ne able to purchase old ODU (outdoor units) with tight seals and a world of RF components and mixer stages for dirt cheap to several hundred watts and very small sensitivity parts in the receive chains. Of course they are in the wrong band but internal microwave shielded enclosures and bulletproof clean power supplies along with a LNA or LNB might interest some. My wish is to setup a station in DC using this method for ham sats. Has anyone alreday done this ? Hint .. old Anacom units. Plus it can and was designed to be integrated into high wind antenna structures. HPA sections can be uncoupled and replaced (I fixed them in remote sites) and replaced with ham sat stuff. Comments welcome.
Samudra N3RDX
Sent from a device with a small screen.
On Thu, Jul 19, 2018 at 4:13 PM -0400, "[email protected]" <[email protected]mailto:[email protected]> wrote:
Hi Dave, You said everything I have learned and observed up until now, but please allow me to add one complication to it -
FM discriminators (aka de-modulators) cannot handle very low signals well, for example, the downlinks of older lower power birds. I observe this when I switch between a vertical and a Yagi, the extra signal strength from even a short 3 element Yagi keeps the FM discriminator very happy.
I find this issue less noticeable in SSB modes and adding a preamp is almost as good as turning up the volume control at the radio.
73! Umesh k6vug
On Thursday, July 19, 2018, 12:07:26 PM PDT, Dave . wrote:
While I'm still new to the sats I have been doing VHF/UHF weak signal work since the 80's and I've always preferred to spend the money on feedline rather than pre-amps. Given that pre-amps amplify the rx noise and signal you really don't improve signal to noise unless the noise figure of the pre-amp is better than your receiver. Usually your just amplifying the signal to make up for the loss that's going to happen as the signal makes it's way down the coax.
You also add complexity when you want to TX on the antenna since you will need to add a t/r relay at the antenna. In addition, you are still losing tx power with the higher loss cable so depending on your ERP goal you may need an amplifier, generally not an issue with the LEO's. LMR-600 or hardline is my feedline of choice for 2m and up. I'm not suggesting that pre-amps can't or shouldn't be used but usually aren't needed if good low loss feedline is used to begin with.
Dave N2OA
On Thu, Jul 19, 2018 at 9:17 AM Roger Titmuss wrote:
Hi as a newcomer to this part of the hobby I have a couple of questions.
- When using the M2 egg beaters how important is it to install a
masthead preamplifier?
- Again with egg beater will 30 watts be enough to get back to the bird?
I am using about 80 feet of RG213 to connect the antenna.
Many thanks
Roger G0AWY
73
Sent via [email protected]. AMSAT-NA makes this open forum available to all interested persons worldwide without requiring membership. Opinions expressed are solely those of the author, and do not reflect the official views of AMSAT-NA. Not an AMSAT-NA member? Join now to support the amateur satellite program! Subscription settings: http://www.amsat.org/mailman/listinfo/amsat-bb
_______________________________________________ Sent via [email protected]. AMSAT-NA makes this open forum available to all interested persons worldwide without requiring membership. Opinions expressed are solely those of the author, and do not reflect the official views of AMSAT-NA. Not an AMSAT-NA member? Join now to support the amateur satellite program! Subscription settings: http://www.amsat.org/mailman/listinfo/amsat-bb
_______________________________________________ Sent via [email protected]. AMSAT-NA makes this open forum available to all interested persons worldwide without requiring membership. Opinions expressed are solely those of the author, and do not reflect the official views of AMSAT-NA. Not an AMSAT-NA member? Join now to support the amateur satellite program! Subscription settings: http://www.amsat.org/mailman/listinfo/amsat-bb
The information contained in this communication is confidential, may be privileged and is intended for the exclusive use of the above named addressee(s). If you are not the intended recipient(s), you are expressly prohibited from copying, distributing, disseminating, or in any other way using any information contained within this communication. If you have received this communication in error please contact the sender by telephone or by response via mail. We have taken precautions to minimize the risk of transmitting software viruses, but we advise you to carry out your own virus checks on any attachment to this message. We cannot accept liability for any loss or damage caused by software viruses. _______________________________________________ Sent via [email protected]. AMSAT-NA makes this open forum available to all interested persons worldwide without requiring membership. Opinions expressed are solely those of the author, and do not reflect the official views of AMSAT-NA. Not an AMSAT-NA member? Join now to support the amateur satellite program! Subscription settings: http://www.amsat.org/mailman/listinfo/amsat-bb The information contained in this communication is confidential, may be privileged and is intended for the exclusive use of the above named addressee(s). If you are not the intended recipient(s), you are expressly prohibited from copying, distributing, disseminating, or in any other way using any information contained within this communication. If you have received this communication in error please contact the sender by telephone or by response via mail. We have taken precautions to minimize the risk of transmitting software viruses, but we advise you to carry out your own virus checks on any attachment to this message. We cannot accept liability for any loss or damage caused by software viruses. The information contained in this communication is confidential, may be privileged and is intended for the exclusive use of the above named addressee(s). If you are not the intended recipient(s), you are expressly prohibited from copying, distributing, disseminating, or in any other way using any information contained within this communication. If you have received this communication in error please contact the sender by telephone or by response via mail. We have taken precautions to minimize the risk of transmitting software viruses, but we advise you to carry out your own virus checks on any attachment to this message. We cannot accept liability for any loss or damage caused by software viruses.
participants (10)
-
Bob -
Dave . -
Jean Marc Momple -
jim＠k6ccc.org -
John Brier -
k6vug＠sbcglobal.net -
Roger Titmuss -
Samudra Haque [TTLLC] -
Tom M0LTE -
Zach Metzinger