Search found 164 matches

by davek
Sat Nov 11, 2017 11:35 pm
Forum: Ask the Engineers
Topic: Removed ye old Transmitter Monitor/Control
Replies: 3
Views: 154

Re: Removed ye old Transmitter Monitor/Control

Complete with "home brew" mouse poop as well
by davek
Tue Nov 07, 2017 12:20 am
Forum: FM Radio
Topic: Nautel NV20 repair/restoration
Replies: 17
Views: 1219

Re: Nautel NV20 repair/restoration

DeepThought: have sent you a PM. I agree that a full schematic of the Tectrol power supply would have been a great help, but not having one was not much of a hindrance in the end. In these situations I like to identify all the major semiconductors and hunt down the data sheets and application notes....
by davek
Mon Nov 06, 2017 5:00 am
Forum: FM Radio
Topic: Nautel NV20 repair/restoration
Replies: 17
Views: 1219

Re: Nautel NV20 repair/restoration

More progress to report, with the last of a few small jobs taken care of: install new blower fans into front door including new connectors re-install low voltage power supply modules re-connect reject loads re-install and connect modulators   With the low voltage power supplies installed and all con...
by davek
Thu Nov 02, 2017 4:10 pm
Forum: FM Radio
Topic: OMB GP-6
Replies: 11
Views: 455

Re: OMB GP-6

I'd be suspicious of the replacement jumpers too. The damaged ones would give you a good idea what their length is supposed to be. I'd also want to know how well the connectors were installed to the new jumpers. I'm not trying to pass comment on the ability of the previous tower workers, but I have ...
by davek
Thu Nov 02, 2017 12:10 am
Forum: Ask the Engineers
Topic: What might this unit be for?
Replies: 6
Views: 296

Re: What might this unit be for?

would the cryptic inscription on the front offer any clues?
clue.png
by davek
Tue Oct 31, 2017 3:25 am
Forum: FM Radio
Topic: Nautel NV20 repair/restoration
Replies: 17
Views: 1219

Re: Nautel NV20 repair/restoration

Hahah .. India Pale Ale is for cleaning the engineer's thirst :lol:

This transmitter will initially be used as a main for a community station (TPO 4kW) so it will have a very easy return to service.
by davek
Mon Oct 30, 2017 5:49 am
Forum: FM Radio
Topic: Nautel NV20 repair/restoration
Replies: 17
Views: 1219

Re: Nautel NV20 repair/restoration

Some more progress was made with a few smaller jobs ticked off the list: The transmitter contains a number of internal reject loads to absorb mismatched power, which contain a built-in directional coupler to measure the amount of reject power. The reject loads had to be stripped down, cleaned and re...
by davek
Mon Oct 23, 2017 6:07 am
Forum: FM Radio
Topic: Nautel NV20 repair/restoration
Replies: 17
Views: 1219

Re: Nautel NV20 repair/restoration

Thanks for the kind words Jeff, happy for you to use the info however you like. I have actually compiled a substantial amount information than what was originally posted (didn't want to get too bogged down with detail). Quite a lot of reverse-engineering was required to understand the various sectio...
by davek
Wed Oct 11, 2017 10:59 pm
Forum: FM Radio
Topic: Continental 816R-3C IPA
Replies: 9
Views: 547

Re: Continental 816R-3C IPA

Another option for to consider: I have seen on Mark Persons' website the work he does to replace failed IPA boards with modules from Broadcast Concepts.

For example...
http://www.mwpersons.com/tech-tips/FM/C ... 5A-ipa.htm
by davek
Sat Sep 02, 2017 2:32 am
Forum: Radio Studio Engineering
Topic: Arrakis Console issue
Replies: 7
Views: 537

Re: Arrakis Console issue

Just a guess: it sounds like that channel has a faulty op-amp that might be dumping DC onto the PGM or AUD buss when the channel is enabled... hard to say without seeing the circuit documents though.
by davek
Wed Aug 16, 2017 6:22 pm
Forum: FM Radio
Topic: Nautel NV20 repair/restoration
Replies: 17
Views: 1219

Re: Nautel NV20 repair/restoration

Work progresses with repairs to both exciters units. As I delve further into this transmitter there is a pattern beginning to form. Any component/PCB/whatever that sits less than 2 inches behind a fan will require attention. The exciter contains 2 power supply modules. A high power module for the PA...
by davek
Wed Aug 16, 2017 6:22 pm
Forum: FM Radio
Topic: Nautel NV20 repair/restoration
Replies: 17
Views: 1219

Re: Nautel NV20 repair/restoration

The 8 PA modules were the next items to work on, which have all suffered from drawing in dirty moist air. The damage was mostly confined to the PCB directly behind the fans, which splits the output of the IPA to drive the final PA stages and distributes DC power to the cooling fans. Each PA was stri...
by davek
Wed Aug 16, 2017 6:18 pm
Forum: FM Radio
Topic: Nautel NV20 repair/restoration
Replies: 17
Views: 1219

Re: Nautel NV20 repair/restoration

If there was going to be any chance of restoring this transmitter, the power supplies seemed like a reasonable place to start. In this model there are 20 main power supplies - 16 for each of the PA modules (plus 2 more for each of the IPA modules contained therein), and 2 power supplies for PA and r...
by davek
Wed Aug 16, 2017 6:17 pm
Forum: FM Radio
Topic: Nautel NV20 repair/restoration
Replies: 17
Views: 1219

Nautel NV20 repair/restoration

Thought the board might be interested to follow the progress of a project I'm currently working on, which is the repair and restoration of a Nautel NV20 transmitter. This TX was installed about 7 years ago; I imagine some of you thinking "why does a 7 year old Nautel need to be restored ?". Well sad...
by davek
Wed Jun 28, 2017 5:45 pm
Forum: FM Radio
Topic: Nautel NV10LT
Replies: 21
Views: 2471

Re: Nautel NV10LT

We have had an NV30 for about 7 years. Had a problem at first blowing PA module 7. After we installed a shorting stub next to the output that problem ended. Now we just go thru a power supply or two a year. Fixed a couple by cleaning the bug juice out of the fan. If anyone (davek) has any tips on r...