W6DHS Tech Log

W6DHS - DSTAR System - Volcano, CA

Your Subtitle text

Serving the Sacramento Valley from the High Sierra.

W6DHS DSTAR system Tech Log

The system is currently running G2 Gateway, DPLUS, DSMON.

January 7, 2009
Installed UHF MA-COM 2-Stage Isolators on W6DHS B and W6KAP UHF systems at Volcano.
UHF TPL Amplifier installed on W6DHS B. Module now has 43 watts out of Amplifier. W6KAP reports
that there is less interaction on Analog with this configuration.

1.2GHz DV module, Pre-Amp, Duplexer and all cables were removed from DHS.
Testing, distance from populated areas and lack of users lead to an end to this evaluation.
Possible new use of this hardware in the Folsom Area. TBA.

Sept 2, 2008 Isolator Installed

DB Products Isolator was tested by K6HLE and mounted on an aluminum panel with 200 watt load for mounting.
Unit was installed by KB6JST and tested. Only .4DB insertion loss.

August 13, 2008 2M Amp Installed
The 2M amp was reinstalled at DHS. Getting 90 Watts out of duplexer. 4 watts reflected.

August 12, 2008 2M Amp Back

The 2M amp was mailed to TE systems on Aug 4th. Unit was received by TE Friday, repaired the same day and shipped back. Unit was received Aug 12. Bypass relay was installed and manual bias circuit was installed. It was determined that the transistors had been stressed, but still had substantial life remaining. Power was measured at 130watts out with 25watts in on 144.960MHz. Normal spec would be 160watts with this input. KB6JST changed the connectors from SO-239 to Type N-Female prior to shipment to TE. Unit was replaced into the fan tray and will installed shortly at DHS.
Jim KB6JST

July 24, 2008 Hardware upgrade

Pursuant to reports of inadequate cabling inside the band modules, KB6JST and W6KAP removed the two meter module after first measuring 21 watts output and 61 watts out of the amplifier. Inside the module were semi-rigid one-tenth inch fully shielded cables that their manufacturer rated at .4 db per meter at 400 mHz. We replaced the cables with quarter inch superflex and then measured 22 watts from the module and 65 watts from the amp. Having made a very modest improvement on two meters, we decided to open the 440 module. We found instead of the semi-rigid low loss cable, two pieces of RG-58A/U. We replaced those with quarter inch superflex. Power out of the module increased from 24 watts to 26 watts

Installed the 1.2 gHz DownEast Microwave pre-amp.

Removed the two meter amplifier for service.

Ernie W6KAP

July 1, 2008 CENTOS 5.2 Update
CENTOS 5.2 was successfully installed. No issues encountered.

June 13, 2008 W6DHS A installed

KB6JST and W6KAP install the new 1.2GHz DV module & duplexer. The system is running barefoot on the same tri-band antenna as UHF.
10Watts output. K6NCR is able to work it from Rancho Cordova on his base station with 1 watt. KB6JST is able to work it fine with 10 watts in Elk Grove mobile. K6BIV is able to barely hear it from Pittsburg and cannot get in. A preamp is on order from DownEast microwave. Due July 15th.
Further testing will commence once it is installed. Unit is on 1284.500 -12MHz DV.

Power was lost at DHS due to the elctra fire. DHS was without power for 27 hours, batteries died at 24hrs.
Service was restored Saturday 7pm pdt.

June 7, 2008

Doug, K6HLE, and I just tested the W6DHS 2 meter REPEATER on its new frequency, 144.96 -.400. The test consisted of using a 0 dbd reference antenna at K6HLE's house in Folsom and transmitting known level signals into the repeater, reducing power using Doug's collection of attenuators until the signal started to exhibit error correction. The point at which error correction could be noticed with 100% intelligibility will be called low% BER, and the point at which error correction made the signal unintelligible will be called high% BER. The signal level was confirmed using HP test equipment. The low% BER level was then entered into the Radio Mobile RF link program to determine what level of signal was expected at W6DHS for that power level and the parameters of the installations on both ends of the path. Here are the results

Transmit power Attenuation low%BER Attenuation high% BER Actual measured output low%BER path distance path condition

0.5 watts 21 db 23db 3.6 milliwatts 36 miles single 18 db obstruction

Radio Mobile projected a signal level of .205 uv at W6DHS at the low%BER. Applying the additional 2db attenuation for the high%BER would indicate that the receiver is starting to decode in the area of .14uv, and is intelligible with noticable error correction in the area of .17uv.

The same test was done on the UHF Repeater.

Transmit Power Attenuation low%BER Attenuation high%BER Actual measured output low%BER

0.5 watts 0 db 1 db .5 watts

Radio Mobile projected a signal level of .233uv at W6DHS at the low %BER.

The difference between the two modules was primarily due to path loss at 440mHz and a lower gain 440 antenna being used at the W6DHS end of the path. The tests are somewhat relative as they rely on the anticipated coax loss and antenna gains rather than actual measurements, but the result is that both systems are exceeding what would be expected of a high performance repeater at a site with a low noise floor. The tests confirmed there was no de-sense in either system, as the range between high%BER and Loss of Signal would have been greater if de-sense was present.

After I reinstalled the duplexer I measured 42 watts out of the duplexer. Further investigation revealed that the 125 watt amplifier was only putting out 63 watts. The module was putting out 22 watts. It appears that the high level of activity on the new reflectors may have impacted the amplifier. Further follow-up is needed.

Ernie, W6KAP

June 6, 2008 Duplexer taken to Telewave in San Jose for alignment. Capacitors were replaced in the the tx side to allow for narrow spacing. DHS C was put back into service at about 6pm.

The output of the duplexer is 42 watts. I changed the cables from the tx to the amp and the amp to the duplexer, still 42 watts. I measured the output of the amp directly into the Bird, 62 watts. The duplexer is doing just what it is supposed to do. Less than 2 db loss. The amp has probably lost a stage. Tomorrow I will measure the output of the Icom TX. If it's 20 watts, then the amp needs work.

W6KAP

June 4, 2008    Duplexer was removed and 2M module taken off line for retuning at Telewave. New freq is 144.96 -400KHz.

May 6, 2008    Duplexer was removed from 2M module and taken to Telewave for retuning. Now get 90 watts out instead of 47.
Unit was tuned and replaced the same day.

April 30, 2008    Noticed a problem with DPLUS while linking DHS C to OMD C and DHS B to JUL C audio from both DHS ports was routed to JUL C. AA4RC was notified and will look into the issue.

April 27, 2008    UHF Amplifier was removed due to possible intermod and desense on VHF. Further investigation is needed to find the solution to this issue. VHF stations are garbling when UHF keys up. Problem fixed once amp was removed.

April 25, 2008    2M Duplexer was returned to Telewave for adjustment. Prior to adjustment power out from the duplexer was 47 watts. Afterwords, 90 watts. Stations now report stronger signals in downtown Sacramento.

April 14, 2008    G2 Gateway comes online. DPLUS is added as is DSMON and the NJ6N logger.

April 9, 2008    DHS Gateway server is wiped and attempt to install CENTOS 5.1 was made. Unfortunately, installation failed and after multiple attempts, it was discovered that the APIC application was conflicting with the new OS causing a failed bootup. W6KAP removed APIC from the BIOS and installation proceeded normally.

Friday, March 21, 2008 we replaced a broken but somewhat functional Comet GP-9 2 meter antenna with a DB Products DB224 dipole array. The array was set for elliptical 9db pattern at 250 degrees pointing at the Carquinez Straits. This is the direction that the Radio Mobile mapping software indicated would produce maximum coverage from our location. Also installed was a Diamond X-6000 triband antenna on top of the DB224.

RESULTS

Before

W6OB's half watt mobile driving around Sacramento area produced many places where error correction occurred and some where dropouts occurred. Roseville required 5 watts and still produced error correction and dropouts

After

W6OB's half watt mobile driving around Sacramento produces few places where minor error correction occurs. Roseville is usable with one half watt with minor areas of error correction.

Before

KI6NHY in Martinez was hitting the the machine very marginally with 5 watts using a twinlead J Pole

After

KI6NHY now hits the machine with a half watt on the twinlead J Pole with no error correction.

Before

N6RDE was hitting the machine in his house in Cameron Park needing 5 watts and hunting for hot spots.

After

N6RDE hits the machine with 100 milliwatts in some areas of his residence and is solid with 2 and a half watts moving around the house.

Before

K6BIV was receiving the system 10 over 9 in Pittsburg.

After

K6BIV now receives the system at 60 over 9.

Before

K6HLE hits hot spots around Pleasanton on 680 and again around Sun Valley Mall Concord using 50 watts mobile

After

K6HLE is solid with error correction from Pleasanton to San Ramon on 680. Intermittent through Danville (behind Diablo) and usable from Oakland exit in Walnut Creek to the Benicia Bridge, receiving full scale readings at points north/east of Benicia on 680 and 80.

What are your observations BEFORE and AFTER?