Repairs were started a few weeks ago on the lightning damage to the repeater, and it is far more extensive then I had originally thought. The lightning did come in on the AC mains, so measures are being implemented to prevent this in the future…
Overall, the only component that does not seem to be damaged is the old MCC RC-100 controller. Here is the damaged item list:
Receiver: blew the LM386 amp for the external speaker.
Exciter: shorted Q4 in the amplifier stage
TS64 CTCSS Board: unknown damage, no longer encodes tone
AP50 Audio Board: destroyed the reverse protection diode and filter capacitor on the power input lines
Power supplies: Both the 12V and 24V power supplies suffered damage
The exciter and receiver have been repaired, and are functioning correctly and well within specs. The AP50 audio board was also repaired, however I will not be putting this back into service, details below.
With the amount of damage done, I figured it’s time for an upgrade to the system. I’ve removed the controller, TS64, and AP50 and will be replacing them all with a Raspberry Pi based controller. Also, I am rebuilding the amplifier to run on 12V instead of 24V. This will make it less cost prohibitive to install a battery back-up, and also easier to maintain.
Parts have been ordered, and repairs will resume shortly. Stay tuned for further updates.
Update: Finally got a chance to work on the repeater. Thankfully, the damage was minimal! The lightning hit the receiver, CTCSS board, new audio board, and possibly damaged the EEPROM on the controller. The only component damaged on the receiver was the LM386 for the external speaker (which isn’t used anyway). The damaged part was removed and the area cleaned.
On the audio board, the lightning took out the reverse protection diode, and filter capacitor. Both of these items were removed, areas cleaned, and new component installed.
The CTCSS board appears to have no damage, but it no longer decodes or encodes tone. A replacement will be ordered.
As far as the controller goes, it still has the CWID on it, but does not respond to any DTMF commands. Even a force reset does not work. We will investigate further, and either repair the existing controller, or perhaps look for a replacement.
Stay tuned for updates!
During the storms last night, we suffered a lightning strike. Initial observation was 147.105 running on batter power, and 224.580 completely off the air. Upon arrival at the site this morning, all circuit breakers were tripped, and the back-up battery for 147.105 was dead (repeater turned off at low voltage level). Breakers were reset, and systems came back up. However, the audio on 224.580 was non-existent. A quick inspection showed burnt parts on both the receiver and the new AP50 audio board. The repeater was removed from the site, and repairs will commence as soon as possible.
Updates will be posted to keep you all up to date.
The 224.580 repeater had been repaired, and is back online. The power amp failed finally, and was somewhat repaired to get it back online. Three of the 5 FETS are dead, so those circuits were removed and bypassed. The amp is putting 20 watts to the feedline, better than the 1.5 watts from the excitet.
The upgrade is to the audio. Since this repeaterhasd been on the air, I’ve never been happy with the quality of the audio. I’ve finally reworked it, and it sounds great! We are now passing “flat” audio thru the system. Give it a try and let me know how it sounds.
Work continues on the next 220 repeater.I’m hoping to have it somewhat on the air for testing soon…
Well, thanks to my new radio, I thought something serious had gone wrong with the repeater. After getting home from work today and fixing supper, I loaded the truck with some tools/supplies and the kids and headed to the site. On the way down, reception of the repeater on the mobile was VERY poor, and the audio very VERY distorted. As I got closer, I noticed I was hearing it fine on the HT, but still poor on the mobile. About 2/3 of the way there I noticed an extra icon on the display of my new Alinco DR-235 that wasn’t there before. I finally remembered what it was…I somehow put the mobile into AM receive. After some random button pressed, I manged to get the radio back into FM mode, and the repeater sounded great like it normally does. Since I was within 5 minutes of the site by then, I went ahead and stopped in to see how it was doing.
The output of the Uniden amplifier had dropped a little more, it is now down to ~50 watts output instead of the original 110+. I need to find a source for some Polyfet F1004 and see about fixing it back up. Installed the rest of the intermod panel, and did some tests. Forward power after all the filtering is 35 watts, reflected at the feedline is less than 0.5 watts. Intermod panel is now complete, and includes a dual port isolator, followed by a low pass filter, band pass filter, then the 4 cavity pass/reject duplexers. I did a quick test for desense by transmitting a very weak signal over the air and disabling the transmitter, no noticeable difference in received signal.
All is well again!