Hello to All,
Looking for suggestions for feed lines to my preamps, could I use RG213-U ? I am thinking this should be ok as both lines will be only about 10ft in length.
From the preamps, I am using hard line.
I also have a UEK3000 receive converter for 2.4 , for feedline, could I get away with RG6, same cable used for sat TV. the run will about 80 ft....
Getting setup for future HEO.s
Any suggestion greatly appreciated and many thanks in advance.
Norman
Hi Norman-Back in the days of A0-40 (sobsob) I used (still do) a 3731AA downconverter with a three foot off center dish (primestar). I ran about 50 feet of RG6 and I found at times I still needed additional attenuation. I applaud you getting ready for the next HEO! If we all did that it might apply some pressure "somewhere".
73 Bob W7LRD
----- Original Message ----- From: "Norman W Osborne" ve3cje@gmail.com To: amsat-bb@amsat.org Sent: Saturday, May 9, 2009 8:44:12 AM GMT -08:00 US/Canada Pacific Subject: [amsat-bb] Hygain Sat Antenna's and SSB UEK3000 Sat.
Hello to All,
Looking for suggestions for feed lines to my preamps, could I use RG213-U ? I am thinking this should be ok as both lines will be only about 10ft in length.
From the preamps, I am using hard line.
I also have a UEK3000 receive converter for 2.4 , for feedline, could I get away with RG6, same cable used for sat TV. the run will about 80 ft....
Getting setup for future HEO.s
Any suggestion greatly appreciated and many thanks in advance.
Norman _______________________________________________ Sent via AMSAT-BB@amsat.org. Opinions expressed are those of the author. Not an AMSAT-NA member? Join now to support the amateur satellite program! Subscription settings: http://amsat.org/mailman/listinfo/amsat-bb
Norman,
From a loss standpoint, almost anything will be fine over the 10' length you
mentioned. The real issue is the quality of shielding, and the placement of the leads. You will be operating in the near field of the antennas, and you want to minimize RX pickup from the TX antennas before you get to the preamps. RG-213 is a single shield coax, while RG-214, Bury-Flex, and RG-9913F have double shielding. While the double shielding is better, especially if the cables run close and parallel to each other, many people do fine with RG-213. Note that the generic versions may have significantly poorer shielding.
The UEK-3000 has 30db gain, and an 80' run with the 2 meter IF output should not be a problem. Back in Ye Olde AO-40 Days, I had a 70' run of RG-8 down to the shack. It was there, I was in a hurry, and it worked. (If you have one with the 70 cm IF, the answer is less certain.) Be aware that RG-6 is 75 ohm rather than 50 ohm cable, the big brother of RG-59, so the SWR on the line will be a bit higher. However, that should not be a problem.
Glad to hear someone else is keeping the faith on HEO.
Alan WA4SCA
Hi Norman,
You mention the use of the Hy-Gain Sat Antennas in you setup. I was foolish enough to purchase this Oscar Link combination of the VB-216SAT 2m 16 element cross Yagi and the UB-7030SAT 70cm Cross Yagi. The antennas themselves are basically OK, but there are serious technical issues with the "Polarization Switch" they supply for changing from LHCP to RHCP.
First of all, as supplied by Hy-Gain, these switches could never work by design.
Some technical explanation - As the T-Match they use on the Horizontal and Vertical driven element presents an impedance of 200 ohms this needs to be transformed at the feed point down to 50 ohms using a 4:1 balanced to unbalanced balun using a 1/4 wavelength piece of co-axial. These seem cut to the right length using the thin RG-316. As per the Satellite Experimenters Handbook and RSGB VHF/UHF handbook, the idea is then to transform this 50 ohms at the feedpoint up to 100 ohms at the switch using a 1/4 wavelength run of 75 ohms co-ax (normally RG-6/U). The two 100 ohms from the V and H will them be in parallel and be 50 ohms again.
So what's wrong with the Hy-Gain switches you ask ?
1: They use RF-303/u 50 Ohm cable from the feedpoint baluns to the Polarization switch, not 75 Ohm cable. This means that at best you will get a 2:1 VSWR through the switch, even if the antenna is perfectly matched. This was confirmed by putting the switch on a Agilent Network Analyzer which I have at work. 2: The cables they use are of equal length. The problem with this is that when you open the switch up, the designers neglected to take into account the extra phase delay through the cheap Tyco Dc relay they use. This meant the phase match between the H and V was off by at least 40-90 degrees from the ideal 180. This means those guys using the switch as it exists will have anything but circular polarization.
To fix the problem I had to practically rebuild the Switching Network by replacing the RG303 with RG-6. The 1/2 wavelength coax inside the switch used to add 180 degrees phase also has to be replaced with RG-6. The 1/4 wave legs then needed to be adjusted by measuring the phase delay on the Agilent Network Analyzer until you get a perfect 180 degree switch between RHCP and LHCP. This a way beyond the capabilities of the average Radio Amateur. Emails sent to Hy-Gain (MFJ) about this issue went un-answered off course.
Other issues : 1: I found that the 70cm antenna had a VWSR dip at around 440 MHz and nothing I did with the match could get it any lower 2: On one of the feed point baluns the "Red" marking on the solder lugs was different from the other 3. This means if assembled as instructed, you would never get circular polarization. There is no way I could have know this. It was only discovered when I picked out the Silicone RTV from the balun and saw the manufacturing mistake on their part. 3: I seriously question the Hy-Gain claim on the data Sheet "True RF, 50 Ohm switching relays are rated for 200W PEP and contribute to improved VSWR". They use cheap Tyco DC switching relays in the design and they are definitely not RF Relays.
My intention is to replace the antennas with the M2 versions in the summer. From the data sheets and correspondence I have has with them it looks like they have done the job properly.
73's Allan Saul ZS1LS South Africa.
On Mon, 11 May 2009 07:31:48 +0200, Allan Saul wrote:
First of all, as supplied by Hy-Gain, these switches could never work by design.
This is not your grandfather's HyGain. MFJ bought the tooling and designs, but not the brains, from Telex. The old crew would not make mistakes like that. I don't think I know anyone from the "old" HyGain who would buy a modern HyGain antenna.
But that's just my opinion.
73
-Jim
-- Ham Radio NU0C Lincoln, Nebraska, U.S.S.A. TR7/RV7/R7A/L7, TR6/RV6, T4XC/R4C/L4B, NCL2000, SB104A, R390A, GT550A/RV550A, HyGain 3750, IBM PS/2 - all vintage, all the time!
"Give a man a URL, and he will learn for an hour; teach him to Google, and he will learn for a lifetime."
HyGain 3750 User's Group - http://groups.yahoo.com/group/HyGain_3750/ http://radiojim.exofire.net http://incolor.inetnebr.com/jshorney http://www.nebraskaghosts.org
Allan, and Norman,
I have the Hy-Gain antennas, but have not had your issues. I did fill the 2 meter antenna with water once and had trouble that way, but other wise they load up and seem to work fine, and the switches help greatly with the fades. My antennas came from MFJ/Hy-Gain via Burghardts. Maybe they were original Hy-Gain stock carried over?
73, Joe kk0sd
-----Original Message----- From: amsat-bb-bounces@amsat.org [mailto:amsat-bb-bounces@amsat.org] On Behalf Of Allan Saul Sent: Monday, May 11, 2009 12:32 AM To: Norman W Osborne Cc: amsat-bb@amsat.org Subject: [amsat-bb] A word of caution - Hygain DB-218SAT Sat Antenna's
Hi Norman,
You mention the use of the Hy-Gain Sat Antennas in you setup. I was foolish enough to purchase this Oscar Link combination of the VB-216SAT 2m 16 element cross Yagi and the UB-7030SAT 70cm Cross Yagi. The antennas themselves are basically OK, but there are serious technical issues with the "Polarization Switch" they supply for changing from LHCP to RHCP.
First of all, as supplied by Hy-Gain, these switches could never work by design.
Some technical explanation - As the T-Match they use on the Horizontal and Vertical driven element presents an impedance of 200 ohms this needs to be transformed at the feed point down to 50 ohms using a 4:1 balanced to unbalanced balun using a 1/4 wavelength piece of co-axial. These seem cut to the right length using the thin RG-316. As per the Satellite Experimenters Handbook and RSGB VHF/UHF handbook, the idea is then to transform this 50 ohms at the feedpoint up to 100 ohms at the switch using a 1/4 wavelength run of 75 ohms co-ax (normally RG-6/U). The two 100 ohms from the V and H will them be in parallel and be 50 ohms again.
So what's wrong with the Hy-Gain switches you ask ?
1: They use RF-303/u 50 Ohm cable from the feedpoint baluns to the Polarization switch, not 75 Ohm cable. This means that at best you will get a 2:1 VSWR through the switch, even if the antenna is perfectly matched. This was confirmed by putting the switch on a Agilent Network Analyzer which I have at work. 2: The cables they use are of equal length. The problem with this is that when you open the switch up, the designers neglected to take into account the extra phase delay through the cheap Tyco Dc relay they use. This meant the phase match between the H and V was off by at least 40-90 degrees from the ideal 180. This means those guys using the switch as it exists will have anything but circular polarization.
To fix the problem I had to practically rebuild the Switching Network by replacing the RG303 with RG-6. The 1/2 wavelength coax inside the switch used to add 180 degrees phase also has to be replaced with RG-6. The 1/4 wave legs then needed to be adjusted by measuring the phase delay on the Agilent Network Analyzer until you get a perfect 180 degree switch between RHCP and LHCP. This a way beyond the capabilities of the average Radio Amateur. Emails sent to Hy-Gain (MFJ) about this issue went un-answered off course.
Other issues : 1: I found that the 70cm antenna had a VWSR dip at around 440 MHz and nothing I did with the match could get it any lower 2: On one of the feed point baluns the "Red" marking on the solder lugs was different from the other 3. This means if assembled as instructed, you would never get circular polarization. There is no way I could have know this. It was only discovered when I picked out the Silicone RTV from the balun and saw the manufacturing mistake on their part. 3: I seriously question the Hy-Gain claim on the data Sheet "True RF, 50 Ohm switching relays are rated for 200W PEP and contribute to improved VSWR". They use cheap Tyco DC switching relays in the design and they are definitely not RF Relays.
My intention is to replace the antennas with the M2 versions in the summer. From the data sheets and correspondence I have has with them it looks like they have done the job properly.
73's Allan Saul ZS1LS South Africa.
_______________________________________________ Sent via AMSAT-BB@amsat.org. Opinions expressed are those of the author. Not an AMSAT-NA member? Join now to support the amateur satellite program! Subscription settings: http://amsat.org/mailman/listinfo/amsat-bb
participants (6)
-
Alan P. Biddle -
Allan Saul -
Gary "Joe" Mayfield -
Jim Shorney -
Norman W Osborne -
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