NVFMA News

Nov 17, 2006: The GE MASTRII repeater was removed and replaced with the spare Vertex VX-5000 repeater. The audio and deviation levels in the Vertex were adjusted using the CE-3 Service monitor. The audio levels in the CAT-1000 repeater controller were adjusted to match the Vertex again using the CD-3 service monitor. Both the receiver and transmitters were reconnect to the single antenna.

Nov 13, 2006: At about 16:00 Monday, Nov. 13, the 79 repeater was no longer on the air. The control operators checked the controller and the controller was responding. A visit to the repeater is scheduled for mid-day Tuesday. Stay tuned for more details.

Oct 10, 2006: K7BC, WC4J, WD5DBC. Adjusted the output audio level in the repeater controller so that it was not over driving the GE transmitter. The problem was that the audio from the repeater was distorted for most users. This was caused when the GE transmitter was reinstalled last Saturday and the audio levels were not properly adjusted.

Oct 7, 2006: 146.91, K7BC, KO1D, KQ4CI, KD4FBT work party to 91. Install replacement GE MASTRII repeater power amplifier. PA is transmitting 135 Watts, measured using a Bird 43 Watt Meter. The power out of the duplexer is 80 watts with no discernable reflected power from the antenna.

September 21, 2006: 146.790. Bruce, K7BC, connected the main site receiver to a different antenna than the transmitter is using. This was done to see if using a separate antenna will improve/eliminate the intermittent interference problem that 79 is experiencing.

Aug 13, 2006: Bruce K7BC, Shawn KA3RQR, and Howard WD5DBC looked into this problem this evening. We were able to duplicate the problem and we think that we know what is going on. The CAT-1000 provides the primary control of the repeater. The timeout timers, reset timer, and hang timers are controller by the controller. The Vertex also has a timeout timer, reset timer, and hang timer. We suspect that the "ringing" and the audio cutoff is be done by the Vertex. The Vertex's timeout timer does not reset on the reset beep (which is generated in the CAT-1000 controller), the Vertex looks at the transmitter on time and until the CAT-1000 hang timer drops, the Vertex is still timing. I will make a trip to the repeater this week and check the Vertex settings.

Aug 13, 2006: The following email was received from a member concerning a problem with 146.91:

The .91 sounded good this morning. The QCWA went over there just before their Sunday net and commented about how good it was to have a repeater that sounded so good in the area again. One problem I heard (and Bruce is aware of through Dick Rucker - caught the tail end of their conversation after returning to the car) is that at every 4 minutes into a conversation there is a ring tone on the carrier. Thirty seconds after the tone, the audio cuts off for ten seconds (time-out), then the repeater returns to normal for another four minutes of conversation.

Aug 8, 2006: 146.940 Adjusted the audio gain into the repeater controller from the receiver. This was not a transmitter problem but rather an audio stage in the controller that was clipping the audio. Adjusted the auto level and tested for proper operation.

Aug 5, 2006: It appears that the receive bandwidth is set too narrow on the 146.910 repeater.

Aug 5, 2006: Work party to 447.025. The controller was reset at which point the repeater started working normally.

Aug 5, 2006: Work party to 91. Vertex repeater, controller, Henry power amplifier installed. The PA is running at a solid 80 watts of output power.

July 39, 2006: Work party to 91. The Vertex repeater was installed and connected to the controller. The controller keys the transmitter and passes audio. The problem is that the controller does not un-key the transmitter. Repeater and controller removed for diagnostics.

July 23, 2006: It appears the the Winlink digi at Massey has a problem, either low power or no power.

July 21, 2006: The MSO, Managed Site Operator, that manages the radios on the Tyson's building has told us that the lease will be renewed. We finally received confirmation that the Tyson's site lease will be renewed. We don't have the lease yet, but we were told that we can pick up keys to the penthouse on Monday and the lease would follow at some point. Not sure when we will actually get the lease since we have been waiting for the lease since March, but with keys we can fix the repeaters.

June 25, 2006: K1DOS picked up the failed GE MASTR repeater amplifier and the parts to repair the amplifier. Hank has 10+ years of experience working with those amplifiers and volunteered to provide the labor to repair the amplifier.

June 18, 2006: RA3RQR checked out the 447.025 repeater to determine why the repeater is down. Shawn learned that the controller is not responding to any of the control codes, including the master control code. The plan is to replace the existing controller with a spare controller on Monday.

June 17, 2006: Work party to 447.025 to check status of repeater. Replaced the failing power amplifier with spare. Measured power output of replacement amplifier at 80 watts using Bird Watt Meter. Power out of duplexer to the antenna was measured at 60 watts and the reflected power was measured at 2 Watts (using 10 watt slug). The repeater receiver receives and the transmitter transmits, but is not "repeating" and the controller does not respond to command codes. Shawn will look at the controller on Sunday.

June 15, 2006: Follow up contact with MSO for the Tyson's site to see as to the status of the lease. Still in progress.

June 3, 2006: Work party to Tyson's Corner site. Locks on repeater cabinets changed. The power supply on 91 checked for proper operation. Confirmed power output of repeater. Removed the failed GE power amplifier. A determination will be made to see if this amplifier is worth repairing.

447.025: Power lever checked and it was determined that the repeater's power amplifier is running at 7 watts. The power supply was checked and it is ok. Both the forward and reflected power for the antenna were checked. Using a 5 watt Bird meter, there is no apparent reflected power from the antenna. It was noted that one of the three fans on the power amplifier is running slow.

The 146.790 remote receiver was checked. The receiver is working properly and the link transmitter is working properly. It was noted that the remote fan is not working and needs to be replaced.

May 27, 2006: KF4LGV is moving so the 146.790 remote that is located at his QTH on Bull Run Mountain needs to be removed. The remote and antennas were removed and reinstalled at KQ4CI's QTH in Ashburn, VA.

May 27, 2006: Testing of the voter and voter adjustments were made for all of the remotes. A PowerPoint presentation of the results of this test is available here.

May 26, 2006: Contact was made with the correct MSO to gain access to the site.

May 16, 2006: 91 disabled due to interference problem and no access to site due to a lease problem.

April 2, 2006: The temporary power amplifier has become intermittent. The repeater has been taken off the air until the replacement amplifier can be installed.

March 15, 2006: Bruce, K7BC, has obtained a replacement amplifier to be installed at 146.91. It will need to be tested and tuned to the proper frequency prior to installation.

February 22, 2006: A replacement power amplifier has been installed at the 146.79 repeater. Bruce, K7BC, headed a work party to the repeater. In addition to the power amplifier, a replacement 60A, 13.8 VDC power supply was installed. The power supply consists of three 20A power supplies in parallel. According to the meter on the power supply, each of the individual power supplies is providing 10 amps of power. The output voltage is not varying under load. Next on the agenda is to work over the receivers.

January 5, 2006: Work party to 79 to check the amplifier. It was found that the amplifier was intermittent after the amplifier was operating for more than a few minutes at a time. A grounding braid was added from the amplifier to the building grounding braid. A separate grounding braid strap was added from the exciter, voter, and controller to the cabinet ground tie point. The intermittent operation of the amplifier did not change. The amplifier was removed and benched. The amplifier was tested with .1, .5, 1.0, 1.5, 2.0 watts of input power drove the output to the correct levels. The output levels were stable and clean. The next step is to check the duplexer for proper tuning. This will be done on Saturday.

January 1, 2006: It appears that the power output levels of 79 is intermittent.

December 28, 2005: Repaired amplifier installed at 79. 400 mw input provides 110 watts of output power.

November 27, 2005: 60 Watt Mirage PA installed and tested at 79. New Henry amplifier returned to Henry for repair.

November 25, 2005: This must be our time for power amplifier problems...... A work party went up to the 79 repeater Friday morning with several objectives. The work party consisted of KI4DTL, KE4MLT, KD4LQS, and K7BC. The primary objectives were: 1: Replace the 110 W PA that was running at 30 Watts with a new amplifier. 2: Attempt to identify the source of an intermod problem. The new amplifier was installed and soon developed some sort of intermittent problem. The amplifier is rated at an 2 watts with a rated output of 250 Watts. The goal was to run the amplifier at 100 watts. With a drive of 400 mw, the output of the exciter, the output of the amplifier was 90 watts. Just as the work party was getting ready to leave, the new amplifier died with a "POP." A visual inspection determined that a coupling capacitor in the collector of one of the output transistors had blown up. The amplifier appears to be gone into parasitic oscillation just prior to the failure. So at this time, the 79 repeater is running 300 mw. We will try and have a different amplifier installed early next week. The under warranty failed amplifier will be returned to the manufacturer on Monday for warranty repairs.

A point of clarification. The amplifier did not actually fail in service. The amplifier was powered up, with both transmitter and antennas connected to the amplifier. With no input power, the Bird WattMeter on the output was showing about 100 watts of power, which it should not be doing with no drive.

November 20, 2005: Temporary power amplifier is installed at 91. The amplifier output is 12 watts, with 8 watts out of the duplexer to the antenna. We also found that the transmit antenna lightening arrestor had failed. It was replaced with a barrel connector until a replacement arrestor can be purchased.

November 19, 2005: Power levels at the 146.91 repeater were checked. The exciter is putting out 300 mw and the PA output is 0. This means that the 300 mw from the exciter is down to about 250 mw after the duplexer.

November 17, 2005: Work party scheduled for November 25 to 79. Items to be addressed: Replace PA, check antenna, break/tighten all antenna mounts/brackets,

November 16, 2005: Tyson's 146.91 output appears to be down. To be checked on Sept 19.

November 12, 2005: Mike and Shawn pick up the 6 meter repeater so that they can complete the 6 meter repeater project.

November 7, 2005: Fairfax County extends the building generator to the 79 repeater.

August 17, 2005: Maintenance Trip to 146.790. K7BC pulled the voter for 146.790 and completely realigned in on his work bench. After the voter was reinstalled he discovered some sort of intermittent audio connection.

August 17, 2005: Site survey to 146.790. K7BC and KI4DTL verified the AC power connections in the radio room for the county. Fairfax County will be reconnecting the repeaters to the building emergency power. KI4DTL is working the the county maintenance personnel to determine exactly what the county needs to do to do the reconnection.

July 21, 2005: The NVFMA Board of Directors voted to replace the existing PA on 146.79 with a new 250 W commercial power amplifier. KQ4CI to order the amplifier. The board gratefully acknowledges the receipt of a $500 donation from Evan Alford to be applied to the purchase of the new amplifier.

June, 2005: Maintenance trip to 146.790. K7BC and WD5DBC. Confirmed power levels on PA. Ran through the adjustments for the voter. Adjusted the levels for the remote. Some of the settings are not adjusting properly. Will need to contact the vendor.

May 2005: Maintenance trip to 146.790 by WD5DBC. Checked all of the all of the connections between the voter, controller, and the receivers. Found that the controller and voter wiring did not match the documentation. Updated the documentation to reflect what was actually installed. Also found that the audio connection for port 3 was broken, moved connectors to port 6 and test ok.

April 29, 2005: Maintenance trip to 146.790. Found that the Power Amplifier is running at 30 Watts. Adjusted the hysteresis for both the Alexandria and Main Site receivers.

Pete and I worked at the Massey building today on the 146.79 repeater. Pete looked at the controller and attempted to enable dial in on-off control of the remotes, but was not successful despite apparently correctly entering the settings. I liked the clean installation at Massey, which I believe was K0RAJ's work. We did succeed in re-aiming the uhf beam from the old Independent Hill bearing to the Bull Run remote. This made a big difference. I can now bring up 146.79 from my bedroom in Ashburn, which I was not able to do before. I want to thank Pete for his help and showing me around. I have a vhf pre-amp, and will try to get out to Bull Run to install it with a cavity or two.

I worked 146.79 inside my van with my HT from the Patent Office in Alexandria to my home. It appears the Alexandria and Tyson's corner remotes are working. There is a dead zone on the Beltway around Merrifield, which suggests the main site receiver is not at peak. The Tyson's remote should probably do better also. There are places on the Toll road where 146.910 is good, but I do not bring up 146.790.

We closed up the equipment room and went up on the roof. Neither compass we had would produce a valid reading (moving a few feet on the gangway on top of the building would yield 90-180 degree swings in the compass) so we re-aimed the yagi by eye. The pole that the Bull Run remote antenna is on would not allow us to aim the antenna exactly where we wanted it, so it's currently aimed about 10-15 degrees too far north from where we wanted to set it. Another vertical pole is in the way, and it's a different diameter so we couldn't just move the mount to the other pole.

73,
Pete

Well, I finally had the time to reinstall the 224.1 power amp.
I installed a new MosFet, and modified the output inductor to relieve the thermal stress.

Please spread the word that the 224.1 repeater is back to full power.
75 Watts out of the duplexer.

June 17, 2004: Beacon Hill remote removed to be installed at Tyson's for 146.790.

May 27, 2004: 220 repeater amplifier no output, removed amplifier. Repeater running on exciter

April 29, 2004: County reconnects 146.790 telephone line, noise on line, county working problem

Dec 18, 2003: NVFMA Holiday Party is declared a success. 28 members and spouses attended the party.

Dec 16, 2003: Autopatch terminated for both the 146.910 and 447.025 repeaters.

Sep 3, 2003: Alexandria remote for 146.790 up and operational. The low audio problem was determined to be a problem in the interconnection between the 2 meter receiver and the UHF link transmitter.

Sep 2, 2003: Alexandria remote for 146.790, very low audio, remote disabled. Red/Tommy to troubleshoot problem on Sep 3.

Sep 1, 2003: 6 Meter repeater link transmitter removed to change link frequency. Existing frequency is causing interference in Alexandria.

Sep1, 2003: Old Bull Run 146.790 remote link receiver antenna re-oriented to point to Alexandria for the new Alexandria remote.

Aug 7, 2003: It is now official, we are loosing the remote receivers for 146.790 and 146.910 that are located at Independent Hill. The television station is clearing the tower of everything so that they can install a HDTV antenna. The antennas will be removed by the end of the week, Aug 8, if the tower work is on schedule.

July, 2003: 6 meter receiver and UHF link transmitter installed at the Massy Building.

April 22, 2003: Vertex reinstalled at 79 after installation of a pre-amp. The preamp improved the sensitivity of the main site receiver from .5 uv to better than .2 uv.

April 19, 2003: Alexandria remote for 79 up and running from the Alexandria Hospital. The antenna at the main site needs to be reoriented and the link receiver installed at the Massey Building.

April 14, 2003: The Alexandria remote for 79 is checked out and up at the Alexandria site. Plans have been made to put up the antennas and turn it on in the near future, de K0RAJ.

Feb 10, 2003: New Henry Radio 130 Watt amplifier installed at 146.790 repeater. Amplifier is derated to 110 Watts. 70 Watts out of the duplexer to the antenna. The main site receiver appears to have a blown input and is therefore out of service.

Feb 5, 2003: Access gained to site, failed temporary mobile amplifier removed. Exciter connected to duplexer with 2 watts output.

Jan 20, 2003: Intermittent no-output on 146.79. Problem appears to be temp PA not transmitting. If you are in the shadow of the Massy building, you can hear the repeater, but very noisy.

Jan 16, 2003: New 130W Power Amplifier for 146.79 arrived, scheduled to be installed on Jan 25

The 28 VDC power amp fuse opened for no reason. Replaced the fuse and all is fine.

Dec 16, 2002: Steve checked the repeater and found that the PA fuse was blown. A replacement fuse will be picked up to be installed.

Dec 13, 2002: Pentagon City/Crystal City remote site dismantled as lease was lost as part of MCI/WorldCom Bankruptcy

Dec 7, 2002: 6 meter/440 receive antenna for 6 meter repeater installed on Massy Building

Dec 4, 2002: 146.910 Autopatch Hang-up command is *. (The hang-up should be #)

November 27, 2002: Net mode of the repeaters has changed. The net mode of the repeaters has been changed to add a short beep when the timer resets.

November 23, 2002: Report from K0RAJ, NVFMA repeater tech: I would say what happened was that the insulation at the point where the 100 watts came of the last output transistor broke down putting a very hi swr on the output. The controller chip U1 looking for this condition, had most likely failed a long time ago (a popular failure in the unit ). Not knowing how much swr, but being very hi, the unit worked until the output transistor went, taking the passive control transistor operated from the output of U1. I think that the GE repeaters in use have out lived their dependability and we should replace all of them as time goes on. The 79 machine has all new units in it except for the PA. I have one PA that is working and U1 has been by-passed in it.

November 22, 2002: 79 Repeater site visit determines that the GE MASTR II Power Amplifier had failed. Vertex exciter is running at 2 watts. Amplifier removed and the exciter is connected to duplexer.

November 21, 2002: Can not hear the 79 repeater. Actually, the repeater could be heard within about a block of the Massy Building.

October 2002: Beacon Hill remote does not appear to be working. Site visit determines that the remote is not receiving anything, ie the receiver is deaf. K0RAJ benched the remote and found that the receiver pre-amp had failed, most likely due to lightening or other static discharge.

Oct 17, at Dominion Virginia Power at Fairfax Oaks, General Membership meeting. Meeting to include special board of directors election and auction to support the repeater upgrades.

August 2002: Interference on 224.100 repeater is solved. Problem turned out to be interference from Fairfax County's helicopter video system that was causing the problem not only with the NVFMA 224.100 repeater but several of the county radio systems.

Sept 2002: Beacon Hill remote down. A quick examination of the remote in the field seems to indicate that either the receiver front end or the receiver preamp was blown.

March 2002: The new 79 Machine was placed on the air in the month of March. The rebuilt machine is operating well, and two of it's four original remotes are back on the air. Watch this space for more updates on the new 79, pictures of the new machine, and other exciting news about our other repeaters, and maybe a new one too!

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