Search found 882 matches

by Dale H. Cook
Mon Sep 23, 2019 1:05 pm
Forum: AM Radio
Topic: Collins 820E-1/F-1 Screen Transformer
Replies: 0
Views: 125

Collins 820E-1/F-1 Screen Transformer

I have a client with a Collins 820E-1 with an open winding in the screen transformer modulator secondary. Would any of you have a scrapped-out 820E-1/F-1 screen transformer whose windings all ohm out with continuity? Collins used the same transformer in the 820E-1 (5 kW) and 820F-1 (10 kW). Failing ...
by Dale H. Cook
Wed Sep 04, 2019 6:20 am
Forum: Ask the Engineers
Topic: PPM Monitor
Replies: 8
Views: 331

Re: PPM Monitor

As one who works in a non-metered market, I have to (jokingly) ask, is the PPM hardware violet in color? Ever since the first discussions of it I've thought of PPM as the Purple People Meter.
by Dale H. Cook
Thu Aug 29, 2019 8:11 am
Forum: Ask the Engineers
Topic: Marti Crystals
Replies: 6
Views: 385

Re: Marti Crystals

rfn wrote:
Wed Aug 28, 2019 6:40 pm
... vaguely remember the original manual having a rather complete retuning/aligning procedure described.
I think that is the case, though I have not changed frequencies on an RPT-15 or RPT-30 in about 25 years. IIRC you will need a deviation meter or service monitor to set the deviation.
by Dale H. Cook
Thu Aug 22, 2019 6:15 am
Forum: AM Radio
Topic: finding AM ground radials
Replies: 41
Views: 4468

Re: finding AM ground radials

rich wood wrote:
Wed Aug 21, 2019 9:07 pm
Go for the direct approach,, Rent a ditch witch and run a trench 90 degrees to the radials.
That, of course, might be useful if you have to fix a radial system, but I don't, as the goal of my exercise is to prevent radial damage.
by Dale H. Cook
Thu Aug 15, 2019 5:40 pm
Forum: AM Radio
Topic: finding AM ground radials
Replies: 41
Views: 4468

Re: finding AM ground radials

An AM loop antenna, a diode detector and a set of hi-z headphones is all you need. ... I use a Tenna tunable AM loop (not ferrite loop) but it is very similar to others sold at Radio Shack, etc. Here I go exhuming an old topic that pertains to a job that I need to do. I no longer have access to an ...
by Dale H. Cook
Wed Aug 14, 2019 7:35 am
Forum: Ask the Engineers
Topic: Belar FMS-2 Meters
Replies: 13
Views: 489

Re: Belar FMS-2 Meters

It has been years since I have worked with an FMS-2, but they should not be pinned with power off.
by Dale H. Cook
Wed Aug 14, 2019 7:23 am
Forum: AM Radio
Topic: Porcelain Insulators Cracking
Replies: 5
Views: 269

Re: Porcelain Insulators Cracking

I agree with Fossil and Deep. You have to use the washers, especially outdoors, to prevent cracking from thermal cycling. Over-tightening is also a major cause of cracking. Years ago I learned a trick from an older engineer when we were rebuilding a 40+ year old 5-tower DA with dozens of standoffs. ...
by Dale H. Cook
Wed Jul 31, 2019 5:33 am
Forum: AM Radio
Topic: LPB Output Transistors (SD-1407 Matched Pair)
Replies: 7
Views: 780

Re: LPB Output Transistors (SD-1407 Matched Pair)

jthorusen wrote:
Tue Jul 30, 2019 7:23 pm
I ended up replacing the whole assembly with a pallet from Broadcast Concepts.
That can't be done with an LPB.
by Dale H. Cook
Thu Jul 25, 2019 2:46 pm
Forum: AM Radio
Topic: LPB Output Transistors (SD-1407 Matched Pair)
Replies: 7
Views: 780

Re: LPB Output Transistors (SD-1407 Matched Pair)

I just checked RF Parts, and they are stocking the ST Micro SD-1407MP at $117.90, so they are again available for overnight delivery at little more than Mouser wants with a six week lead time.
by Dale H. Cook
Thu Jul 18, 2019 9:16 am
Forum: Ask the Engineers
Topic: Cutting Hard Line
Replies: 12
Views: 356

Re: Cutting Hard Line

W9PXZ wrote:
Wed Jul 17, 2019 8:08 pm
I was not aware they made them big enough to do 3"
A friend who is engineering director of a statewide system of NPR stations has a Rigid that will do 6" hardline (that is what their flagship station uses to feed a 5 bay).
by Dale H. Cook
Mon Jul 15, 2019 6:57 am
Forum: FM Radio
Topic: Harris Z FM FET replacement
Replies: 7
Views: 406

Re: Harris Z FM FET replacement

radio_guru wrote:
Sun Jul 14, 2019 8:47 pm
I bought an inch/pound torque tool on E-bay.
I use an American-made low-range torque wrench which cost about $80.00 and came with a calibration certificate.
by Dale H. Cook
Fri Jul 12, 2019 12:07 pm
Forum: FCC Discussion
Topic: FCC FM Query Data Base
Replies: 12
Views: 423

Re: FCC FM Query Data Base

When I was a kid I enjoyed the occasional Scooter Pie in my brown-bag school lunch. It wasn't until I moved south in 1984 that I encountered the real deal - the Moon Pie from Chattanooga Bakery. It became part of my standard fee invoice until I had to drop it after developing diabetes a decade ago. ...
by Dale H. Cook
Fri Jul 12, 2019 10:14 am
Forum: General Computers
Topic: How to Delete a Post
Replies: 5
Views: 1654

Re: How to Delete a Post

Click "The Team" at the bottom of the window and PM one of the admins with your question.
by Dale H. Cook
Fri Jul 12, 2019 10:12 am
Forum: FCC Discussion
Topic: FCC FM Query Data Base
Replies: 12
Views: 423

Re: FCC FM Query Data Base

RGORJANCE wrote:
Wed Jul 10, 2019 9:27 am
My standard fee for "stuff" is a cup of coffee, payable next time we meet.
Fossil -

What? You don't even bill a kringle?
by Dale H. Cook
Fri Jul 12, 2019 10:08 am
Forum: FM Radio
Topic: Harris Z FM FET replacement
Replies: 7
Views: 406

Re: Harris Z FM FET replacement

The physical replacement appears straightforward. The one thing that may be critical in the physical replacement is the torque. If the manual doesn't specify replacement torque I like to measure it. I use an analog dial inch-pound torque wrench with a follower needle. The follower needle shows how ...