Any communications grade low impedance dynamic mic should work fine if you hook it up correctly.  Even older CB radio import mics if they are low impedance and dynamic.  

As for the hum when in the dock, likely due to AC filtering, the old electrolytic caps in there could be gone and need replacement.  Do that first.  If there is still a hum problem, inspect the regulator circuit for cold solder joints -- and the "little" cap in there on the base of the series pass transistor.  

If the hum is light hum and not motorboat hum, it *may* be something else, but those electrolytic filter caps are always suspect when the rig starts to get long in the tooth, should be blanket replaced anyway IMO.  



KE3WD

With a 200W rig I wouldn't bother unless and until the day came when funds and such allowed consideration of going for about a gallon (1KW) output.  That can get expensive real fast, consider also antenna limitations, power source additions in the mobile possibly, RF probs that may have to be dealt with, etc. before anything else.  

Always always, better antenna beats mo' power, whether mobile or fixed operation.  

Problem with antennas and mobile is legendary, but there are things you can do right now that can increase your sig with little outlay, consider fixed operation from the mobile by adding some more wire to the end of any vertical HF antenna that can be tuned, alligator clip to end of vertical and wire shot up through tree, etc. for an inverted L kind of situation.  Especially good for the low bands, this can increase your signal for literally pennies on the dollar.  All that you need is the gator clip and some length of insulated wire...  I've even used 22AWG "sacrificial" enamel covered wire for such things, if you have to suddenly drive away, you can.  


KE3WD

Check the tube sockets first.  

Solder joints, also the tightness and plating of each socket.  

Switch tubes and see if the dark one lights in the other socket.  

Sometimes the best cure is to order up a good pair of 3-500Z ceramic sockets to suit and install them.  


KE3WD

But if you play or sing the staff music presented there, it does not rhythmically sound like CW at all.  

I think the composer may have consulted a Morse table to come up with this, but really didn't have a clue as to proper Morse timing, etc. or he would have placed things differently.  The "rhythm of the code" is so important to copy.  Nobody who really knows the code would ever think that anyone could copy the hidden message from what is written there, that would be more of a pencil and paper "decoding" -- which obviates the use of Morse, the one digital code that can be translated using nothing more than the two holes on either side of the head and the stuff in between.  


But it does represent a creative mind seeking ways to create.  

I've played around with various musical themes and CW over the years, too, but have the resource of actually knowing and using the code behind it.  Sometimes it is amazing how the Morse can be hidden, rhythmically correct, by simply implying the frequency changes known as melody to the thing.  Even commonly used short Morse abbreviations and the like can escape the ear of seasoned CW operators once the pitches are implied.  I will still use a CW rhythm to iterate jazz improvisations inside a tune from time to time.  Even when told to look for 'em, some of my 40WPM and better friends can't often find them.  "QSO" spread out over the scale can sound completely alien, even though it is still rhythmically correct.  


Thanks for posting that,


KE3WD

WB2WIK makes a good point, I was going by memory there, of a long time ago.  

Try it the "other way round".  

Sorry for the confusion.  


KE3WD

>>by ONAIR on October 4, 2007  
 
Or for a really simple solution, just use a switch to disconnect the speaker wires!<<


NEVER pull this stunt on a tube driven audio output amplifier.  

The output transformer will be subjected to high intenral voltages with no load (the speaker) attached -- this could lead to expensive repairs.  


KE3WD  

The LM 567 was a tone decoder chip designed to provide a saturated transistor switch to ground when an input signal is present within the passband.  

Originally designed for inexpensive use as Touch Tone decoder, The circuit consists of an I and Q detector driven by a voltage controlled oscillator which determines the center frequency of the decoder.  

Ah, google coughs up a datasheet:

http://web.mit.edu/6.115/www/datasheets/LM567.pdf

We'll leave the argument as to whether or not the thing is a true PLL for another time, it could be wired up to act like one and so for all intents and purposes I guess it is one.  

Here is a Spanish page that has the PCB on it, mentions Popular Electronics magazine, may be the circuit in question here or close to it, not much else and no schematic I could find there:

http://py2mg.qsl.br/Filtro%20CW%20PLL/FILTRO%20CW%20PLLtxt.pdf

Mainpage:  http://www.py2mg.qsl.br/

It appears to have been set up to act more like a bandpass filter than anything else.  

I once incorporated the 567 as a 50KHz bandpass filter for a specified ultrasonics design, there was a design kit for this chip that may still be available, you would get two chips, various components and the design and application notes, wouldn't be too hard to set one up as a ~600-800Hz bandpass filter for CW.  The thing wouldn't ring, that's likely what the boon would be.  


KE3WD

This is simple enough, you will need a second relay that operates from the same control voltage as your antenna switchover relay.  Wire its coil in parallel with the antenna switch coil.  (117VAC?)

Then connect one set of the N.O. (Normally Open) contacts on that relay to the two screws at the Receive/Stby terminals.  

If you connect those two screws together, the receiver will mute.  You can test that fast using a pair of needle nose pliers that have insulated handles, just touch the points to the screws and watch the receiver mute.  Front panel switch must be in the Receive position at all times for this to work.  


KE3WD

I'll bet a call to Alpha would get you some part numbers...

Understood, Lon.  

But that was my point also.  

I, too, have some boat anchors around and use them on occasion, Straight Key Nights, etc.

But they do not do a lot of duty around the shack for reasons of performance (lack thereof as compared to more modern gear), age, etc.  

I wish I had a dollar for everytime I've heard of a newer ham picking up a radio with an analog dial on it and then desperately seeking a digital readout that will work with the rig...

?

Very good suggestion about those Heathkit DX series, you could add the DX-60 to that list also.  

Some other nice CW xmtrs to look out for would be the EICO, the little AMECO units, etc.  

Building one from scratch today using new parts might just prove to be not so cost effective without a lot of substitutions, etc.  

The one factor that seems to get to far too many is that VFO thang.  You don't really need one to enjoy CW.  A few rocks for the 40 meter band, plus learn how to "rubber" a xtal, man.  I fondly remember opening up those old crystals with the screw on covers, which the designation of escapes me now, and trimming xtals, even writing big Xs on them with lead pencil to lower the freq a few.  

If you really have to be frequency agile, that's what the new rigs are for.  Get to know how it REALLY was back in the day, not very many Generals had VFOs either, and, of course, for the Novice, it was rockbound by regulation.  


KE3WD

Interesting, eh Lon?

Those of us who lived through the drift-O-matic Swan era, the chirp-O-matic Heathkits, the damn Goonie Birds and all their inherent problems and foibles, just can't understand what this new interest in the boat anchor stuff is all about.  Now that we have rigs available from at least six major sources, foreign and domestic, plus a few others, that were things we only dreamed about back in 1965.  And they are available for pennies on the dollar by comparison.  

Yet there is this big interest in using all the problem rigs of the past -- and damn near all of them were, with the one exception being the Collins rigs which most of us could not even think about being able to afford back then, which are now in much older shape to boot.  

Go figger.  

"Hey, what's the frequency for the Swan net tonight?"

"Just pick any freq. on the band and wait for 'em to drift on by, man..."  


:-)


KE3WD

I think (actually I know) that those Molex connectors are often problematic.  

Do what Alpha says first.


KE3WD

Or the little blue Bournes 10-turn pots...

Collins Collectors Association


http://www.collinsradio.org/