Search found 928 matches

by ChuckG
Wed May 16, 2018 11:05 pm
Forum: Ask the Engineers
Topic: C-band TI
Replies: 21
Views: 399

Re: C-band TI

Yes... Fairchild Dart 384. It was the better receiver of the two IMHO, you could change transponders with a thumbwheel, the SA required you change crystals. A lot of folks made a reed relay crystal switching contraption to allow for changing SA transponders. SEDAT was actually an upgrade for these r...
by ChuckG
Sat May 12, 2018 11:59 pm
Forum: Everything else
Topic: Am I a possible engineer candidate?
Replies: 7
Views: 239

Re: Am I a possible engineer candidate?

I can't add a whole lot to what TPT already said and I agree with all of it. Unless you are in a large market, the pay is often bad, the benefits do not exist and the hours are awful. We do it for love, not money lol. Perhaps that is fine with you. If so.... SBE membership and certification is nice ...
by ChuckG
Sat May 12, 2018 11:42 pm
Forum: Ask the Engineers
Topic: C-band TI
Replies: 21
Views: 399

Re: C-band TI

The Microdyne receivers had a 70 Mhz IF as well.

Deep Thought wrote:
Sat May 12, 2018 9:38 am
Our 1982-vintage UPI and NBC audio dish was 70 MHz second IF. Was kinda fun to tune around on the SCPC carriers with a comms receiver and listen in back then. :)
by ChuckG
Wed May 09, 2018 7:02 pm
Forum: Ask the Engineers
Topic: C-band TI
Replies: 21
Views: 399

Re: C-band TI

jantonuk wrote:
Wed May 09, 2018 3:46 pm


Single channel not a good solution as I need three different transponders, 1, 17, 21
You can install a tuned filter to notch out in-band interference, as long as it doesn't land on top of one of your transponders.
http://www.microwavefilter.com/c-band-lp3.html
by ChuckG
Wed May 09, 2018 12:25 am
Forum: Ask the Engineers
Topic: STL Frequencies
Replies: 12
Views: 267

Re: STL Frequencies

These days my Paul Bunyan imitation consists of eating pancakes. Preferably "all you can eat". :lol: Trees have been a PITA with the 950's too. Had to put up a power pole at one site to get over a row of pines, moved the receive dish 100' up the tower at another for the same reason. Now another site...
by ChuckG
Wed May 09, 2018 12:22 am
Forum: Ask the Engineers
Topic: STL Frequencies
Replies: 12
Views: 267

Re: STL Frequencies

This is such a short path that you can see clearly one tower from the other. Problem is it's over a fairly industrial area
and interference worries me with unlicensed stuff. The other alternative is using public internet with Barix boxes, but that's another set of possible issues.
by ChuckG
Mon May 07, 2018 11:06 pm
Forum: Ask the Engineers
Topic: STL Frequencies
Replies: 12
Views: 267

Re: STL Frequencies

Well there goes that plan lol.
This would be bringing program audio from one transmitter site to another transmitter site to feed an FM translator.
That's pretty clearly not "TSL" use.
by ChuckG
Sat May 05, 2018 11:14 pm
Forum: Ask the Engineers
Topic: STL Frequencies
Replies: 12
Views: 267

STL Frequencies

Can a 450 Mhz RPU be used for STL duty legally? Not temporary emergency use, but full time?
by ChuckG
Fri Apr 27, 2018 6:50 pm
Forum: Ask the Engineers
Topic: Temperature Sensor for Remote Control
Replies: 4
Views: 165

Re: Temperature Sensor for Remote Control

LM34 (lm35, lm335Z, etc) will do it for about a buck fifty.
therm0.gif
therm0.gif (7.6 KiB) Viewed 162 times
by ChuckG
Tue Apr 10, 2018 7:17 pm
Forum: FM Radio
Topic: FM3.5 odd problem
Replies: 9
Views: 338

Re: FM3.5 odd problem

The FM3.5 uses a solid state relay in the primary of the plate xfmr. Nice work finding that. Would never have guessed to look there. Harris had a field upgrade for that, adding a magnetic contactor. The contactor went in the plate primary circuit,the SSR then got rewired to operate just the contact...
by ChuckG
Mon Apr 09, 2018 7:58 pm
Forum: FM Radio
Topic: FM3.5 odd problem
Replies: 9
Views: 338

Re: FM3.5 odd problem

It's quicker to lift them all up off ground at once and put a small fuse between transformer/choke chassis and ground. The blown fuse will tell you which iron has the problem.
by ChuckG
Sun Apr 08, 2018 6:20 pm
Forum: FM Radio
Topic: National over Eimac or Econco
Replies: 21
Views: 720

Re: National over Eimac or Econco

Installed a Harris HT-5 waaay back in the early 90's. First factory new tube lasted well over 38,000 hours. Second tube - a rebuilt - lasted a year, third lasted back up in over 25,000 hours. Recent years, life has been pretty good with rebuilts. The rebuild in our HT-5 has chugged along for 39,420...
by ChuckG
Fri Apr 06, 2018 7:49 pm
Forum: FM Radio
Topic: National over Eimac or Econco
Replies: 21
Views: 720

Re: National over Eimac or Econco

RGORJANCE wrote:
Fri Apr 06, 2018 6:45 am
How long did your's last???

Fossil
I put one in a Collins 2kW FM and hit the plates, lights went out, destroyed the socket.
by ChuckG
Fri Apr 06, 2018 7:45 pm
Forum: AM Radio
Topic: GATES ONE IRF-350 REPLACEMENT
Replies: 9
Views: 543

Re: GATES ONE IRF-350 REPLACEMENT

Chuck: The old metal TO-3 case version is what Jon is working on for the mod to the TO-3P. Good. Those have gotten expensive and it's only going to get worse. One particular SX I worked on had intermittent RF and some bizarre faults.. I found someone had replaced the FET's by prying them off the bo...
by ChuckG
Thu Apr 05, 2018 10:39 pm
Forum: Ask the Engineers
Topic: Sage ENDEC Printing
Replies: 7
Views: 183

Re: Sage ENDEC Printing

Is there a requirement to actually print and store the EAS logs on paper?
I keep the Sage emails in weekly folders and keep a separate single-sheet "station log" to sign off on EAS, Tower lights, etc, but don't attach the sage alerts to that log. They are archived in the "EAS" email account.