View Full Version : Palomar Amp
06-18-2003, 12:03 PM
I have a Palomar 400 watt amp and need info on proper tune-up and/or manual. It has 6 small tubes and has 4 band settings:10-15-20-40. Please send info to: firstname.lastname@example.org Todd
Palomar Electronics Corporation was a manufacturer of linear amplifiers (almost exclusively for the CB market) in the 1960’s and 1970’s. This company went out of business about 1980. #
Palomar is currently a registered trademark of Palomar Engineers, Inc. -- which has NO connection with the former Palomar Electronics Corp.
The Palomar 400 manual is NOT available on K4XL's BoatAnchor Manual Archive (BAMA)
This manual is available from a number of web sites focused on the CB market. #A google search should find an appropriate vendor near your QTH.
Your specific amplifer's design was based upon cheap and readily available "sweep tubes" used in televisions (1950s - 1970s) before the migration to solid state electronics in North American televisions in the 1970s. #The choice of the power tube was a major contributor to the low cost of the Palomar 400 and other amplifers,suchas the Dentron GLA-1000. #Most of these designs used four 6LQ6, so-called "sweep tubes," in parallel. #
After the demise of sweep tube manufacturing in the US & Western Europe in late 1970s, original stocks of various types, including the 6LQ6, remained on the shelves of repair shops and tube dealers. #As the supply has dwindled, the price of these tubes has increased --according to the law of supply and demand. #Today, the cost for four 6LQ6 tubes exceeds the value of the linear amplifier (other than collection purposes). # http://www.qrz.com/iB_html/non-cgi/emoticons/sad.gif
The only current production sweep tube EL509 is manufactured by Svetlana (St. Petersburg, Russia) for the Eastern European television market.
Some amateurs have converted these amplifers to the EL509 tube - since it is still in production
Best of luck.
06-18-2003, 05:23 PM
If it is the 300A it used either the 6LF6 or 6KD6 (depending when it was made..)..the tubes are not a 'cheap date' today..running about 45-55 dollars apiece..
They are not as forgiving as say the 6146 or 811's as far as tuning it wrong.
If your using more than 10 watts drive..use the low power setting. This bypasses the two driver tubes.
You can run up to about 60 watts drive in the low power setting..(about 40 is optimal)..if you run it more than 10 watts in the HIGH power setting you'll fry the toobs.. http://www.qrz.com/iB_html/non-cgi/emoticons/tounge.gif
Load to max outpoot with the tune and load caps into a dummy load. Make sure the antenna is resonant.
Recommend you bring it up slow on a variac and change out the caps before using..spray some deox in the switches and caps...
It's not a bad little amplifier for 10-40 meters with some TLC. Very simple construction. Easy to repair. (Has boards for caps, preamp etc easily taken out and repaired.)
As far as 'CB'..have heard this time and again...
Lots of Heathkits SB-200's and others have been used for 'CB'..
Somehow this is supposed to give the amp a bad name. Surprisingly lots of them still putting out RF after decades. Hey, if it puts out RF and it's cheap, can be worked on..go for it..she will put out enough RF for a respectable signal while some guy pays thousands and sounds the same. Also working on these little guys you learn alot.
I rebuilt one (300A) for my Globe Scout for AM..
As an amatuer, we use what we got.
Here's a website for instruction, they also have a scedmatic. http://www.cbtricks.com/
With a little work would make a nice little amp.
Jim, KD7KOY is correct about the price of tubes.
Which Palomar model that you have will make a big difference. For example, the model 310M and Skipper 300 (a 4 tube unit) used the 8950 tube. The last NOS price I had for the 8950 tube was $ 100 each. Ouch!
At that price you can purchase a number of used 80 - 10 meter RF amplifiers with tubes (usually 572B or 811) with more power output.
IF your tubes are all good, operate as outlined in manual -- and it will last quite a long time.
06-19-2003, 03:47 AM
KOY: There is a big difference between using a Palomar Amp and any Heath Amp. Look at the output spectral purity. The Palomar will have so much trash, you would be very surprised. Heath Amps on the other hand, perform quite well and are pretty darn clean. More than you can say for an original Palomar. Greg tried to give a little "history" of Palomar and what they were doing. Using TV Sweep tubes was not really the best thing to do, but at the time, it was cheap.....and we mean cheap in more ways than one.
Some people called them TV Killers....they did that well.
06-20-2003, 05:06 AM
Bill..I never said that a Palomar was better than Heath..only that both have been used illegally..
I have used a Palomar 300a and no problem at all as far as TVI (One sitting not 3 feet from two computers also..). Most of the problems results from poor tuning, bad shielding and grounding. Granted, Palomar is not the #1 amp out there..but for amatuer use, cheap and a little care, it works just as well as some homebrew amps I've seen on the air.
The most important point I'd like to make is..
As amatuers it is part of the hobby to take a 'bad' piece of gear and make it work..improve it..we are getting to the point of 'plug and play' and 'reviews'. If that little amp is not as good as some, let's experiment and make it work better.. 73