Will normal crystals work in a BC-610

[K1YTG]

I have been working on a BC-610.  The BC-610 crystals I have work in the tuning units.  But my crystals such as I used with Heathkits DX-35 or DX-60 are not working. 
Are the crystals I have no good.  Or does the BC-610 require a different type of crystal.  I have made an adaptor to be able to get a connection between the base and the socket and I think the connection is good.
Norm

[AC5UP]

Do some research on the various crystal types (like third overtone or 'AT cut') and you'll find there is no such thing as a normal crystal... "Normal" being a substitute word for something like standard, universal, etc. Also be aware that a tube circuit can load a crystal with heavier current than the typical chip circuit used today. It's usually not a good idea to plug a crystal into an older piece of gear before you've looked at the schematic. A 'power' oscillator tube like a 6CL6 or 6GW8 was often used to develop a healthy carrier signal ahead of the PA and as long as the crystal was rated for the designed current and power level things were OK... Lesser crystals might go toes up on short notice.

I'm no expert on crystal oscillators, but I know they can vary and do expect a certain characteristic in the rock else they won't work.

[K1YTG]

I did use the word normal in the heading, but I was more specific in the text.
The transmitters I have had from the 60's novice era all used the same type crystal.  They could go in WRL, Heathkit, Ameco, Multi Elmac, or Johnson transmitters.
That is the type I have had over the years. 
But they don't seem to function in the BC-610.

Norm

[G3RZP]

Modern crystals have plated on electrodes - HC/6-U size crystals are like that. In the BC610 era, crystals were in holders, usually with an air gap between the electrodes and the crystal. Additionally, many of them were X or Y cut, rather than AT cut of the plated types - the WW2 style FT243 non plated crystal were AT cut too, but had an air gap. This made them easier to grind at home to move them a little way, although etching was better in maintaining the profile. X and Y cut are quite a bit thicker - for example, the 456 kHz crystal in the original HRO crystal filter is 0.25 inches thick. Plated crystals are usually rated to work at about 1 mW, and many of the older transmitters run at quite a bit more. An old trick was to use a 60mA bulb in series with the crystal, and even that at times didn't protect the crystal against excessive current. Especially so in a 'Tri-tet' circuit if the tuning was wrong.

Assuming the crystals are FT243 type, and are OK, they are probably good for the BC610, but I would really like to see the circuit diagram to go much further. I would be very wary of using modern small crystals, though.

[KA5N]

If you don't know what type of crystal you have (FT-243, sealed metal can, glass envelope,
etc.) then describle them.  I suspect that you have FT-243's which are about two inches
(including pins) long  one inch wide and about  a quarter inch in thickness.  Held together
with three screws.  Made of plastic or bakelite and metal.  These were made by the jillions
for the military.  If the crystals in the 610 don't look the same as the ones you are trying to use then they probably aren't the same, or may have lost their activity (which can usually be
restored by cleaning the crystal element and the contact plates).
If you are stymied, then take pictures and post them on one of the free sites like photobucket.

Allen

[WB2WIK]

Everyone should have a BC-610 and carry it around as needed.

Better than a boring cardio workout or weightlifting with dumbbells.

I never had a BC-610, but the old FT-243 holder crystals I've used a lot and were popular since WW2 seemed more robust and capable of higher dissipation than almost all "ordinary" crystals made since that era.  They seemed to work with just about anything.

[N2EY]

I have been working on a BC-610.  The BC-610 crystals I have work in the tuning units.  But my crystals such as I used with Heathkits DX-35 or DX-60 are not working.

The crystals you have used in the Heathkits are almost certainly "FT-243" or similar. They have two small pins a bit less than 1/2 inch apart.

Are the crystals I have no good.

Do they still work in the Heathkits? If so, they are good.

  Or does the BC-610 require a different type of crystal.  I have made an adaptor to be able to get a connection between the base and the socket and I think the connection is good.

The main concern is that the crystal current of the BC-610 oscillator stage may be too high for FT-243s. That transmitter was designed for use with larger crystals that could handle more power.

However, the oscillator stage is only a 6V6GT, so you may be OK. The thing to do is to try it out with a non-ham-band FT-243 xtal that you can afford to lose (into a dummy load, of course!)

The better solution is a VFO.

73 de Jim, N2EY

[KB2FCV]

Bry, AF4K sells them here:

http://www.af4k.com/FT171_crystals.htm

I think I picked one or two up for when I had a BC-610. I wound up selling it all before I was able to get around to it (there was no way I could get it in the new place we bought). As others said, it's probably best to find the right crystal that matches considering some of the current that travels through.

[G3RZP]

From memory, the BC610 used crystasl with a 3/4 inch pin spacing: they could have been AT cut, but larger blanks than FT243, which would allow a lower power density per unit of area.