Has anyone experienced any malfunction in transmitting on their Icom 9700 on the 1.2 gig (L-Band Mode)? My SWR’s are registering 3+ and I’ve changed antennas twice with direct connection/ connectors using N adapters. I’m using LMR 400 coaxial (50 foot) run. The power coming out of the radio is 8 watts via dummy load/meter. The antenna is from M2 and requires no tuning.
Not sure what else I can do?
Sloan (KN4GQB
Best option would be put an antenna analyser on the antenna, never trust pretuned antennas.
Peter, 2M0SQL
On Fri, 28 Feb 2020, 00:48 Sloan Davis via AMSAT-BB, [email protected] wrote:
Has anyone experienced any malfunction in transmitting on their Icom 9700 on the 1.2 gig (L-Band Mode)? My SWR’s are registering 3+ and I’ve changed antennas twice with direct connection/ connectors using N adapters. I’m using LMR 400 coaxial (50 foot) run. The power coming out of the radio is 8 watts via dummy load/meter. The antenna is from M2 and requires no tuning.
Not sure what else I can do?
Sloan (KN4GQB _______________________________________________ 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: https://www.amsat.org/mailman/listinfo/amsat-bb
Sloan,
The other thing I would suggest is using either LMR600 or even better hardline. The calculated loss of 50 feet of LMR 400 at 1.2G is 2.3 dB by one online calculator. Assuming you get your SWR down into the 1.2 range, you will get about 4.5 watts to the antenna. May be okay depending on what you are doing. I always worry when I spend half my money on heating up the coax.
I used my 9700 in the January VHF contest on 1296 with no problem. The antennas where a pair of Directive Systems 45 element loopers fed with 7/8" hardline. Way overkill for satellites if that is what you are going to use your station for and the direct answer to your question is the 9700 worked fine.
Agree on the need the get an antenna analyzer on the system if you can. The other thing while you are at it is to TDR your cables. We have traced more problems to bad connectors than I care to admit. Anymore when things are strange that is where we start. A quick check might be to put your dummy load on the end of the coax instead of the antenna and see what the SWR is.
Hope that helps
John
On Thu, Feb 27, 2020 at 7:48 PM Sloan Davis via AMSAT-BB [email protected] wrote:
Has anyone experienced any malfunction in transmitting on their Icom 9700 on the 1.2 gig (L-Band Mode)? My SWR’s are registering 3+ and I’ve changed antennas twice with direct connection/ connectors using N adapters. I’m using LMR 400 coaxial (50 foot) run. The power coming out of the radio is 8 watts via dummy load/meter. The antenna is from M2 and requires no tuning.
Not sure what else I can do?
Sloan (KN4GQB _______________________________________________ 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: https://www.amsat.org/mailman/listinfo/amsat-bb
Directive Systems antennas are known to be well engineered and assembled. I have been to many antenna ranges to find that measured results are within 0.1 dB of claimed specs. Still, your points-of-failure include: Icom 9700 antenna jack. Check to make sure the center "fingers" of the N connector are not damaged or otherwise askew. Use different coax and retest. A problem with either connector can inject high SWR. Ditto if the coax itself has been crushed at any point along its length. Place a 50 ohm dummy load at the far end of the coax and retest. If it shows low SWR, then the problem is truly with the antenna; call directive systems with this information. They will take care of you. Here's hoping that these suggestions help (or offer you insights that eventually lead you to a solution). Kindly, Ev, W2EV
On Thursday, February 27, 2020, 7:48:21 PM EST, Sloan Davis via AMSAT-BB [email protected] wrote:
Has anyone experienced any malfunction in transmitting on their Icom 9700 on the 1.2 gig (L-Band Mode)? My SWR’s are registering 3+ and I’ve changed antennas twice with direct connection/ connectors using N adapters. I’m using LMR 400 coaxial (50 foot) run. The power coming out of the radio is 8 watts via dummy load/meter. The antenna is from M2 and requires no tuning.
Not sure what else I can do?
Sloan (KN4GQB _______________________________________________ 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: https://www.amsat.org/mailman/listinfo/amsat-bb
-
Ev Tupis -
John Kludt -
Peter Goodhall (2M0SQL) -
Sloan Davis