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 Post subject: Quartz Crystals
PostPosted: Sep Wed 20, 2017 3:51 am 
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Have any of you used FT-243 quartz crystals sold by AF4K? Are the crystals of good quality, reliable, etc? I would like to pick up a couple 160 meter crystals to use with a Heathkit DX-100B and I see that AF4K sells crystals cut for the ham bands.

Brad K4RT


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 Post subject: Re: Quartz Crystals
PostPosted: Sep Wed 20, 2017 5:17 am 
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I have bought HC6U crystals from him and returned them. I assume that they did work. I just didn't like the appearance. There are almost no sources for crystals right now, so maybe I was unwise to place a possible relationship with Brian in jeopardy. However, at the time, International Crystal was still in business.

Norm

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 Post subject: Re: Quartz Crystals
PostPosted: Sep Wed 20, 2017 7:52 am 
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QuartsLab also makes amateur crystals.
http://www.quartslab.com/

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 Post subject: Re: Quartz Crystals
PostPosted: Sep Wed 20, 2017 12:35 pm 
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Brad,

Most of the crystals AF4K sells are small crystals inside a FT-243 holder and they won't like the crystal current of many older transmitters. I have a couple of his for 3885 that I use in my Ranger/Desk KW and Viking 500 stations and there is frequency shift at the start of every transmission. They hold up OK for AM in these transmitters but wouldn't be suitable for CW because there would be a major keying chirp.

Check and see whether he still has "real" FT-243 crystals. The oscillator in the DX-100 is equivalent to those used by Johnson since the DX-100 is copied in part from the early Johnson Viking 1 and 2 so I expect you will have the same experience I have with these crystals.

Rodger WQ9E


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 Post subject: Re: Quartz Crystals
PostPosted: Sep Wed 20, 2017 6:20 pm 
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I was wondering why you would need crystals since the DX-100 has a built-in VFO. Maybe just for convenience?

The trend these days is to hollow out a FT-243 military crystal and stuff a modern tiny crystal inside, that is made for microprocessor type applications. I see these on eBay with Brother P-Touch labels stuck on them showing the "new" frequency (Not to be confused with the 1980's products of CW Crystals, where he was grinding new blanks and putting them into surplus FT-243 holders with paper labels showing the new frequency, which were fine.)

None of these "new" tiny crystals will handle the current that some of the more primitive novice class transmitters pull through them and they will chirp or fracture sooner or later. Something more sophisticated such as a DX-100 or Apache is going to be easier on the crystal but you may experience chirp as mentioned. Depending on the application, they may be fine. Your mileage will vary.

There is no crystal manufacturer left that makes FT-243 holder style crystals. You may still be able to get the HC-6 holder with the fat pin adapters from overseas, but the cost is not pleasant.

I am sure I am not the only one who, as a kid 50 years ago, used to rummage through huge barrels of crystals at military surplus stores trying to find anything in the novice bands and never finding a single one, nor any in the ham bands at all!

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 Post subject: Re: Quartz Crystals
PostPosted: Sep Thu 21, 2017 3:51 am 
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I have about a dozen of Bry's FT-243 crystals that I received with my Globe King 400B. They have been used with the GK for several years without a problem. I laugh when I read comments about why they won't work with high power transmitters. The GK is a legal limit transmitter. Most of these "experts" have never tried them. :roll:

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 Post subject: Re: Quartz Crystals
PostPosted: Sep Thu 21, 2017 12:46 pm 
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I don't doubt that the AF4K crystals will work fine in many applications but as I noted they aren't well suited for every vintage transmitter and there is a bit over one second of rapid frequency shift every time these crystals are started in my Ranger and Viking 500 transmitters. I have a pair of them so it isn't just one crystal doing it, they behave exactly the same way and will do so in any of the Johnson or similar transmitters using this 6CL6 oscillator circuit which was originally designed for the actual FT-243 crystals.

WRL used a 7C5 crystal oscillator in many of their transmitters and it is VERY crystal friendly, I have a Globe Champion 175 and a Globe King 400 and they both use this oscillator circuit. But a real FT-243 crystal is suitable for more crystal current than the small HC-49 units that AF4K puts inside FT-243 cases and rigs that were designed around the upper end of FT-243 specs are going to have crystal heating and drift issues with these hybrid crystals.

If in doubt about whether it will meet your needs order one and check whether it behaves in your rig's oscillator circuit. I have made 15 minute transmissions using these crystals and they haven't died so they do work OK for AM in the Johnson rigs although people may comment on the startup frequency shift but if used for CW in a Johnson rig it will sound like a very bad directly keyed VFO. I have a true FT-243 crystal for 3880 which works beautifully in the Ranger/Desk and Viking 500 setups with no change in frequency at the beginning of the transmission.

I have nothing against Brian and his crystals and I have bought both radios and crystals from him. They work very well in some rigs but not so well in others and that is why some of us are cautioning people to check whether they are suitable for a given application. I acquired a couple of new "grind your own" FT-243 crystal kits on ebay that are from the 1950s and include a couple of holders, blanks, and instructions. It is time I try my hand at crystal grinding to see how it works out because I would like to have a couple of stable 3885 crystals for my Johnson rigs.

Rodger WQ9E


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 Post subject: Re: Quartz Crystals
PostPosted: Sep Fri 22, 2017 1:44 am 
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Geoff Fors wrote:
I was wondering why you would need crystals since the DX-100 has a built-in VFO. Maybe just for convenience?


Geoff, Yes. The VFO in this DX-100B is very stable, but I do like to use crystals at times.

Pete, thanks for the link. I will check out quartslab.com.

Roger, I will think this over a bit more. I might post a WTB listing in the classified sections here for a genuine FT-243 crystal for 1880 or 1885 Khz. This is for the DX-100B I had posted about in this forum in recent weeks. I put it on 160M last Friday night for an AM QSO with a local here, and the next morning on 40M CW with the local weekly CW group. So far, the transmitter is stable and working FB.

Thanks all for your thoughts on this.

Brad K4RT


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 Post subject: Re: Quartz Crystals
PostPosted: Sep Fri 22, 2017 4:27 am 
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Location: Long Beach Ms. USA 39560
To grind your own crystals, starting with a below-the band rock I bought one square foot of 1/4 inch glass with rounded-over edges. I taped down 3 sheets of sandpaper, 250, 350 and 1200 grit. Grind with the coarser grits and restore activity with the 1200 grit. Wash them well before testing - dust changes the frequency.
I only did a couple, but it works.
73,
Pat W5THT

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 Post subject: Re: Quartz Crystals
PostPosted: Nov Fri 10, 2017 1:34 am 
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So I'm working on a rather unique transmitter with about 28 crystals in both HC49/U and HC6/U packages. (B&W 6100).

CoolBruceLong determined that these crystals are fundamental rather than 3rd overtone. One of the crystals was bad, 25.000 mHz HC-6/U.
So I purchased from Mouser 25 mhz fundamental in both HC-49/U and HC-49S (tiny) packages.

I tried first the HC-49s inside the HC-6/U base with appropriate load capacitance. It works. The data sheet calls for a maximum drive level of 500 uW. I found online a document from an xtal manufacturer that indicates drive level of HC-6/U crystals in my frequency range could be 4 mW.
Not to mention the phyiscal size of the replacement is tiny in comparison to the old crystal - so I'm certain I'm overdriving it. However, it works today. From what I've read overdriving can result in fracture and at minimum premature aging/freq drift.

I would love to be able to measure the actual current, though don't have a current probe nor calibration equip.

Next up I'll try the HC-49/U crystal, and datasheet says 1 mW maximum. For the cost (30 cents) I can keep making these and change them out should the drift. However, I'm lucky that the frequency I need was available.

+1 on the grinding idea - it's on my list to experiment with.

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 Post subject: Re: Quartz Crystals
PostPosted: Nov Fri 10, 2017 4:29 am 
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SmoothOscillator wrote:
I would love to be able to measure the actual current, though don't have a current probe nor calibration equip.


I am fortunate enough to have the RFL-459A Crystal Impedance Meter, so I can measure impedances and crystal current from around 800 k/c to about 15 M/c or so... It's a GREAT piece of test equipment, and even has a BNC output that I use with my GenRad 1191 frequency counter.


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 Post subject: Re: Quartz Crystals
PostPosted: Nov Fri 10, 2017 1:45 pm 
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I believe the HC-49u unit will be fine in the "crystal synthesized" 6100 transmitter; I also have one of these. The HC6 was the smallest commonly available crystal when the 6100 was designed so it was used but the very low power oscillators in the 6100 are easy on the crystals and the current should be extremely low causing no problem for the HC49 crystal. The HC6 size is more robust and was used in higher power oscillator circuits like those used in direct exciter chains common to tube type CB radios and simple amateur AM/CW rigs.

If the crystal is being driven too hard there will be obvious drift as the crystal element warms during operation. Measurement of crystal current in the operating equipment circuit for these low power crystals is no trivial task.

I also have used HC49 crystals in several Drake 4 line twins over the years after I found a box of them for 12.6 Mhz. which is the crystal needed to put the 4 line on 160 meters.

Now you need a Clegg FM27B for two meters so you will also have a similar crystal synthesized rig for 2 meters :)

Rodger WQ9E


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 Post subject: Re: Quartz Crystals
PostPosted: Nov Fri 10, 2017 2:13 pm 
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I’m not familiar with the 6100. I’m wondering how HC6/U or HC49 crystals would stand up in the oscillators used in the Heathkit DX-100, TX-1, or WRL Globe King 500B transmitters.

To our veterans here: Thank you for your service to & sacrifices for our country.

Brad K4RT


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 Post subject: Re: Quartz Crystals
PostPosted: Nov Fri 10, 2017 2:28 pm 
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bfo wrote:
I’m not familiar with the 6100. I’m wondering how HC6/U or HC49 crystals would stand up in the oscillators used in the Heathkit DX-100, TX-1, or WRL Globe King 500B transmitters.

To our veterans here: Thank you for your service to & sacrifices for our country.

Brad K4RT


I have a couple of crystals I bought that are FT-243 cases with HC6/U inside and they are usable with my Johnson Ranger and 500 for AM but I wouldn't try them on CW. They have a very noticeable drift for the first few seconds after startup however they haven't cracked but this sort of drift would create a horrible sustained chirp on CW. The crystal oscillators in the classic Heathkit gear were copied from Johnson so they would behave the same in those rigs; the Globe Kings have a similarly designed crystal oscillator.

The best bet for using low power crystals with older vintage rigs is to build a solid state external oscillator (could easily be battery powered) and use it like a VFO to drive the big rig. Although it could be built in the size of a book of matches I would suggest a small case with a switch to select multiple crystals.

Rodger WQ9E


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 Post subject: Re: Quartz Crystals
PostPosted: Nov Fri 10, 2017 3:12 pm 
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rsingl wrote:

I have a couple of crystals I bought that are FT-243 cases with HC6/U inside and they are usable with my Johnson Ranger and 500 for AM but I wouldn't try them on CW. They have a very noticeable drift for the first few seconds after startup however they haven't cracked but this sort of drift would create a horrible sustained chirp on CW. The crystal oscillators in the classic Heathkit gear were copied from Johnson so they would behave the same in those rigs; the Globe Kings have a similarly designed crystal oscillator.

The best bet for using low power crystals with older vintage rigs is to build a solid state external oscillator (could easily be battery powered) and use it like a VFO to drive the big rig. Although it could be built in the size of a book of matches I would suggest a small case with a switch to select multiple crystals.

Rodger WQ9E


Very interesting. I have a Post called "Keying my MOPA" in which I describe frequency drift in the first few seconds after I apply B+ to the oscillator tube. My thought was it was a voltage regulation problem, but all my "FT-243" crystals are HC6/U stuffed into FT-243 cans by Brian. Maybe that is more what is going on here.

FWIW, my transmitter is a 6AG7/807 MOPA, about 50 watts output so I am beatin' that rock hard. Maybe I should try a real FT-243 before I go muckin' around with my power supply.

paul


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 Post subject: Re: Quartz Crystals
PostPosted: Nov Fri 10, 2017 3:17 pm 
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Quote:
I’m wondering how HC6/U or HC49 crystals would stand up in the oscillators used in the Heathkit DX-100, TX-1, or WRL Globe King 500B transmitters

For the low price of crystals at Mouser (assuming they have the right frequency and mode) just give it a try.

Quote:
RFL-459A Crystal Impedance Meter
Thanks for the tip!

Quote:
the very low power oscillators in the 6100 are easy on the crystals and the current should be extremely low causing no problem for the HC49 crystal.

I bet you're right - Inside the synthesizer are a bank of hardwired HC-49s for the 10 kHz digits...the fact that their small size is present is indicative of the drive level...and also makes me wonder why they weren't used throughout the radio.

Looking forward to experimenting w/crystal modification...wish I hadn't sold that big box of xtals a few months back :x

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 Post subject: Re: Quartz Crystals
PostPosted: Nov Fri 10, 2017 3:27 pm 
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Location: Potomac, MD 20854
I just bought a "real" 7025 kc FT-243 from AF4K, I will report back if the frequency drift is any better than what I have with the "stuffed" FT-243 holders. FWIW, I also use those HC49's in FT-243 holders that you can get on eBay and they work pretty well even for a 50 watt MOPA.

paul


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 Post subject: Re: Quartz Crystals
PostPosted: Nov Fri 10, 2017 3:29 pm 
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K3STX wrote:
Very interesting. I have a Post called "Keying my MOPA" in which I describe frequency drift in the first few seconds after I apply B+ to the oscillator tube. My thought was it was a voltage regulation problem, but all my "FT-243" crystals are HC6/U stuffed into FT-243 cans by Brian. Maybe that is more what is going on here.

FWIW, my transmitter is a 6AG7/807 MOPA, about 50 watts output so I am beatin' that rock hard. Maybe I should try a real FT-243 before I go muckin' around with my power supply.

paul


Paul,

I would bet those crystals are your problem. I bought mine for when I was often acting as net control for the regional AM net on 3885 and I didn't want to fool with constantly resetting the Johnson VFO to stay exactly on frequency. The first few seconds of crystal drift is very noticeable when there is hetrodyne interference between two AM stations or if the transmitter carrier is monitored via a receiver with BFO.

Try to borrow a real FT243 from someone nearby and I bet your MOPA chirp issue disappears. The rig you describe isn't hard on FT-243 crystals and they should key without drift. A B+ supply isn't going to take seconds to stabilize after a load change; the voltage change between the previous state and the new loaded state will be abrupt.

Rodger WQ9E


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 Post subject: Re: Quartz Crystals
PostPosted: Nov Fri 10, 2017 3:49 pm 
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Location: Potomac, MD 20854
rsingl wrote:
K3STX wrote:
Very interesting. I have a Post called "Keying my MOPA" in which I describe frequency drift in the first few seconds after I apply B+ to the oscillator tube. My thought was it was a voltage regulation problem, but all my "FT-243" crystals are HC6/U stuffed into FT-243 cans by Brian. Maybe that is more what is going on here.

FWIW, my transmitter is a 6AG7/807 MOPA, about 50 watts output so I am beatin' that rock hard. Maybe I should try a real FT-243 before I go muckin' around with my power supply.

paul


Paul,

I would bet those crystals are your problem. I bought mine for when I was often acting as net control for the regional AM net on 3885 and I didn't want to fool with constantly resetting the Johnson VFO to stay exactly on frequency. The first few seconds of crystal drift is very noticeable when there is hetrodyne interference between two AM stations or if the transmitter carrier is monitored via a receiver with BFO.

Try to borrow a real FT243 from someone nearby and I bet your MOPA chirp issue disappears. The rig you describe isn't hard on FT-243 crystals and they should key without drift. A B+ supply isn't going to take seconds to stabilize after a load change; the voltage change between the previous state and the new loaded state will be abrupt.

Rodger WQ9E

Rodger, that would be great if it solved my problem. I also have a little VXO in the circuit to try to "bend" the frequency. Based on my examination of literature/web I expected plus or minus at least 1 kc, but I am able to bend only about plus/minu 0/5 kc. Maybe these little crystals are harder to bend than a real FT-243.

paul


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 Post subject: Re: Quartz Crystals
PostPosted: Nov Fri 10, 2017 3:53 pm 
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Location: SW WA state
K3STX wrote:

FWIW, my transmitter is a 6AG7/807 MOPA, about 50 watts output so I am beatin' that rock hard. Maybe I should try a real FT-243 before I go muckin' around with my power supply.

paul


Paul,

I have a fairly good selection of 75 & 40M FT-243's: If you're good in the callbook (QRZ nowadays!), I'll be happy to send you a real FT-243 so you can see how they work for you.

-Tom


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