Call Search
     

New to Ham Radio?
My Profile

Community
Articles
Forums
News
Reviews
Friends Remembered
Strays
Survey Question

Operating
Contesting
DX Cluster Spots
Propagation

Resources
Calendar
Classifieds
Ham Exams
Ham Links
List Archives
News Articles
Product Reviews
QSL Managers

Site Info
eHam Help (FAQ)
Support the site
The eHam Team
Advertising Info
Vision Statement
About eHam.net

   Home   Help Search  
Pages: Prev 1 [2]   Go Down
  Print  
Author Topic: Drake TR-7 and MFJ 969 bad vibes.  (Read 7654 times)
AC2EU
Member

Posts: 450


WWW

Ignore
« Reply #15 on: October 25, 2012, 08:52:32 PM »

I'm late to the party, but:

1) try the radio with just the dummy load with no tuner. If it doesn't give full power or shuts down, the radio has a problem.
2) If it passed test 1, the general procedure for all manual tuners is to initially tune for maximum receive noise before attempting to transmit tune. This is no guarantee that it is the proper tuning solution, but you will probably be close in most cases.
After the receive is happy, then and only then do I go for low power transmit tuneup.

Consult the tuner manual for recommended preliminary settings.

Once you find the sweet spots, keep a note book of what the best settings were for a given frequency and antenna.

Jim
AC2EU
Logged

W8IJN
Member

Posts: 3


WWW

Ignore
« Reply #16 on: October 26, 2012, 06:03:26 AM »

Jason,

I never kept the log book I had for the serial numbers came under my paws over 30 years ago, but I believe you are looking at two problems. One is the shutdown problem, something a TR7 will do when the current draw is too high on the PA, which is obviously the result of the antenna tuning process. Second is how the PA reacts to high swr/hard-to-tune antenna situations.

Easiest fix for both is turn down the drive. Tuning at a lower power level and then increasing the power out as you tune is usually a whole pile more easy than brute-force "here's all the RF I got" antenna tuning.

Of course, a solid ground & maybe even a yard full of radials/ground lines makes a big difference in any set-up. And if you've been through a couple lip-burnings from RF on the microphone as I have, you can learn that lesson a couple hundred times before it sets in. That's how it works for me.

I'm trying to remember all the other goofy things a TR7 will do under less than optimal conditions but it's been 30+ years & I can't even remember where I put my checkbook or keys. I think there's a ham shack around here somewhere too.

Good luck!

73

Nils
W8IJN
Logged
AC2EU
Member

Posts: 450


WWW

Ignore
« Reply #17 on: October 26, 2012, 07:35:58 AM »

Jason,

After reading about all of your trials and tribulations, you might want to consider buying a modern radio that has an automatic tuner and fold back protection.
Sorry to say, but you may have smoked the finals in your radio with improper tuning procedures. The oldies are a lot less tolerant of mismatches than the new ones.

Jim
AC2EU

Logged

K8AXW
Member

Posts: 3958




Ignore
« Reply #18 on: October 26, 2012, 08:51:08 AM »

Quote
After reading about all of your trials and tribulations, you might want to consider buying a modern radio that has an automatic tuner and fold back protection.

YSF:  After reading this thread from the start to the last, let me recommend something.

STOP everything and get another ham, preferably one with a few years experience, to assist you.  From what I read, you understand absolutely nothing about your gear, operational procedures and steps to take to find out what is wrong.

So far you have taken steps that may have wiped out parts in the radio and adjusted controls in the power supply that will require proper usage of a meter to get them back where they belong.  Returning pots to "their original spots" very seldom works.

5UP was spot on when he suggested RTFB!  This is ALWAYS the first step when working with a new piece of gear.  While reading the manuals is considered "unAmerican" by some, please believe me that it is absolutely necessary for new hams.  There are just too many things that can go wrong.

I mean no disrespect OM but you are in over your head and need help; more help than you will get on this forum. 
Logged
WB2WIK
Member

Posts: 20633




Ignore
« Reply #19 on: October 26, 2012, 09:08:01 AM »

YSF I wish you were closer (I'm down in L.A.), I'd be happy to help you out with the TR-7.

I've owned my TR-7 since it was new in 1978 and must say in 34 years it has never failed in any way (of course the pilot lamps burned out many years ago and I've replaced them with LEDs).

The TR-7 transmitter does have self-protection circuitry, and the original PA design was very robust and could easily transmit just fine into pretty bad mismatches.  In fact, the TR-7 literature (data sheets, marketing stuff) proclaimed it can run 50% of normal output power into a 4:1 VSWR, and I've found that to be about right.  (A 4:1 VSWR isn't a short circuit, however; I've never tried that. Wink ) It's rated 10% of normal output power into a 5:1 VSWR.  See data sheet here: http://www.wb4hfn.com/DRAKE/DrakeCatalogsBrochures/Brochure_TR7_04B.htm

The PS-7 power supply is very robust also.  In 34 years, I've actually never had the cover off of my PS-7.  I use compressed air to blow the dust out of it every few years, just poking the air through the holes in the covers.  Never had it open.

So, I suspect either you have a bad PA or some other problem that could be quickly and easily identified.  The TR-7 is plug-in-board construction as you know (mother board/daughter board construction, like a computer) and there are hundreds of pins making hundreds of connections with hundreds of mating pins; I've found "most" TR-7 problems relate to a pin connection becoming oxidized and not making proper contact.  I can tear out all the boards and re-install them in about 15 minutes, and I've done that a couple of times with various TR-7s over the years.

There's also a small bias regulator that enables the PA to work, and that has been the subject of failure in many reports.  Easy and cheap to fix, if that's what it is.

Logged
KG6YSF
Member

Posts: 91




Ignore
« Reply #20 on: October 26, 2012, 11:40:20 AM »

Yes: I am in over my head. I thought I made that fairly clear. Roll Eyes

No: I don't understand most of the technical stuff in the manual, I read it. Huh

Yes: I understand the I can't remember alot of stuff, my pain meds do that to me, I have post its everywhere. Wink The V.A. is great at handing out narcotics but horrible about actualy fixing our vets problems. Thinking in tech terms through a fog of pain killers isn't easy!

I have quit doing anything with the radio and power supply, except cleaning. The wifes tired of it being on the table. Maybe when I get it back together I'll sell it as a project piece.


Logged

"Rangers Lead The Way!"  "Sua Sponte"   "Litalis Velox Silens"
When all else fails ham radio is there!
FT2900, FT8900, VX6, Ft60, TS940SAT, Drake TR7, MFJ 969
K8AXW
Member

Posts: 3958




Ignore
« Reply #21 on: October 26, 2012, 08:56:08 PM »

YSF:  First of all there isn't a great deal of "technical" stuff to read and remember on how your radio is supposed to work. 

I know that many radios have switches and knobs up the wazzoo but that still shouldn't be a problem.  Tuning the transmitter part for proper operation isn't all that "technical" either.

Your retention problem caused by whatever is just something that you need to work around and getting inside of the transceiver or the power supply shouldn't be necessary.

I also suffer retention problems and until I was 18 years old simply thought I was stupid....sometimes I thought border line retarded.  However, once I learned that I wasn't either I took steps to compensate.

Let me suggest a few things, based on my personal experiences.  With many of us with this "problem" there is a tendency to panic when confronted with a piece of gear that appears complicated.  Also there is a tendency to panic when confronted with an operating manual that is often very extensive and detailed.

My suggestion is to take the manual and jump to the part where you hook up an antenna and do it.  From then on just familiarsize yourself with each control by the description in the manual.  Stay in the receive mode until your comfortable using it.

Before trying to transmit with it, read and reread the tune up instructions until you can comfortably do that.  Stay away from external gear like antenna tuners, just tuning into a dummy load.  That way you have nothing to complicate things for you.  All transceivers are designed to operatin into a 50 ohm dummy load without any external gear. 

If it doesn't work doing this, get some help.  Don't complicate things by making adjustments inside the box or the power supply. There's nothing more disconcerting for someone trying to help you but first having to listen to all the things you screwed up or down that you shouldn't have.

OK, so you have a health and med problem.  You know this.  Don't let it be a crutch or a major hindrance to you.  Work with it or around it.  Sometimes it's very difficult but if you want to do .....whatever.... you will have to do it.  Or you can give up and sell the damn thing. Cry

Good luck.

Logged
W6MQI
Member

Posts: 32




Ignore
« Reply #22 on: November 03, 2012, 10:00:16 AM »

 I have several Drake rigs and this thread makes me sad  Sad to think this rig might be wasted what a drag. How hard is it to read the manual or maybe suck it up and get help from some local ham hopefully one that knows what's going on! not some CBer with all the controls set to 11. YSF: if you don't know what a CW key is it's time to STOP and get some help buy a ARRL handbook, operating handbook, and get to know the local club there's more to this hobby then memorizing a few questions and passing a test. Good Luck I really hope the rig is ok

 73,Dave
Logged
Pages: Prev 1 [2]   Go Up
  Print  
 
Jump to:  

Powered by MySQL Powered by PHP Powered by SMF 1.1.11 | SMF © 2006-2009, Simple Machines LLC Valid XHTML 1.0! Valid CSS!