Wanted crystals

I have one at 833 kHz in a HC6 case. This might be useful for you to repair and test the transmitter and then you could buy one for the frequency you want.

There is no reference I could find for a Z-1A holder so you may have difficulty finding this. You can probably adapt an HC6 to the socket.

Neil

Try Halted Electronics (halted.com) they are local to me, and carry a suprising number of electronics stuff you typically think you have to buy in bulk.. (not radio related, but I was even able to find Z80 and 65C02 processors there)

Thanks for the offer. That frequency is just past the top of the sub-band this transmitter is set for. It is also an odd split and not on 10 KHz spacing. Possibly useful for testing into a dummy load. If this 660 KHz rock I have tests bad, I may want to try yours

Joe

I checked Halted, but they had nothing even close. Thanks for the suggestion.

Joe

I have a Radio Systems Phase II transmitter.  It was crystalled for 650 kHz but the crystal is actually 2600 kHz.

A frequency divider is used (selectable divide by 4 or by 2) and the crystal can be used for either 650 or 1300 kHz.

Do you know if your crystal is cut for the actual working frequency or like mine which is a multiple?

I understand that the crystals for this old tube rig are fundamental.

Sure wish I could find a manual.

Joe

Joe,

Without knowing your level of experience or willingness to do so, I suggest the following which is based on my experience repairing tube type radios and TVs in my past. It is much easier with a schematic but it is possible without one. I couldn't afford Sam's PhotoFax at the time so I learned to do repair without a schematic. Here are some general tips:

Do a thorough visual for damaged components such as leaking capacitors, burned resistors, damaged wiring. In tube circuits it is easy to check resistors in circuit with an ohmmeter (power off, or course) and the nominal values can be read from the color codes. It is almost impossible to check coils for shorts however and fortunately they rarely short. Non electrolytic caps can fail but this is also rare. Tubes can be checked with a tube tester if one is available. If not, then at some cost they can be checked by substitution. Tube failure is not as common as most people believe.

Confirm that the power supply is working and that the filaments light. In the low power circuits the B+ voltage should be 200 to 300 volts.

Check each stage for proper operation. In this case this would mean to start with the oscillator and get it working. Once this is done, follow the signal through the other stages. An oscilloscope is very useful for this but a high impedance AC voltmeter can also be used. In tube circuits, the signal most often goes in the grid and out the plate. You can find the tube basing diagrams on the internet. One good source is http://tubedata.milbert.com/index.html
The tube bias can be checked with a DC meter. The grid is negative with respect to the cathode by several volts.

The usual caution about working around high voltages applies. You really do need to be very careful. You may not want to tackle this if you are unsure of your safety since the voltages used in tube circuits are dangerous.

Neil

I'm gonna drop by Halted on the way home from work to see if they have any of those crystals in stock.  Is it possible for you to take a photo of the crystal? I'm a visual sorta fella, and I can't find a reference to what you describe on the internets.

MLR,

That is very kind of you. If you find anything for the low end of the AM band, please let me know what frequencies they have and the cost per crystal.

Here is a high resolution picture of a Z-1A, next to a FT243. You can see that the Z-1A is about 1/8" taller, twice as wide and maybe 1/16" thicker. The pins are much larger.

I Googled, but can't find any information on this type of crystal. I do find information on the manufacturer.

Joe

Neil,

Thanks for the suggestions. Good advice for the newbie. However, I am familiar with what needs to be done with old tube gear. I have refurbished and aligned quite a few AM BCB radios and a few Amateur rigs.

The reasons I would like a manual is twofold: the schematic is nice to have to check wiring and values, in case something has been previously "fixed", or parts markings are unreadable; I want the manual for tuneup instructions. So far, all I have is something to the effect of tweak the two trimmer caps and the coil with the slug for maximum brightness on the neon bulb.

Joe

The 1020 kHz crystal in my RC-6A is a little

bit smaller than the size the transmitter

takes.  I ran some wires into the crystal

socket and attached them to the crystal.

This is not easy to do, and you have keep

all safety precautions in mind.

But doing that did get my

transmitter running.  If you try a

crystal that is too small, the crystal

will get unstable or shatter because

it won't be able to handle the energy

going through it.

Good luck.  I hope you find something

that works.  I will take a look around

the internet.  If I see anything I will

let you know.

It's a great ransmitter.

Bruce, The DOGRADIO Group

I thought I would look around on

E-bay to see what was out there.

It turns out a guy had a crystal

for 620 kHz in an HC6/U holder, which

may or may not have worked in the

RC-6A.

The item is no longer available - but -

it does show that there are crystals

out there from time to time.  I know

this was not a channel you are

interested in - but you never know

what might show up.  AF4K has some

crystals around 500 kHz.  Some people

are still grinding crystals.  As you know,

you can only raise the frequency. 

This is a very long shot of course.

I always wanted to try grinding

crystals for fun, but never got

around to it. 

Bruce, The Dog Radio Group

Joe,

When I posted the how to on tube equipment repair I did not know your experience. You should be good to go considering what you have done!

We'll leave the post for others who might benefit.

Hope you solve the crystal problem even if you have to resort to some "make do" solution.

Neil

It's always so good to hear from you!

I was thinking the same thing - what I
mean is - my entries on this thread
are aimed at Joe (Hi Joe!) and also
all of the other readers out there.

So when I mentioned the safety issue -
I knew Joe would get that - but others
reading this stuff for the first time
might not have known.

Best Wishes,
Bruce, The DOGRADIO Group