Forums :: Resources :: Features :: Photo Gallery :: Vintage Radio Shows :: Archives :: Books
Support This Site: Contributors :: Advertise


It is currently Jun Wed 28, 2017 1:11 pm


All times are UTC [ DST ]





Post New Topic Post Reply  [ 15 posts ] 
Author Message
 Post subject: What Crystals are used in the Gonset G-12 Communicator CB?
PostPosted: Nov Fri 25, 2016 6:37 pm 
Member
User avatar

Joined: Jan Thu 06, 2011 6:32 pm
Posts: 258
Location: Bethpage, NY
I thought I had ordered the right freq crystals from Ken's, but no good, off frequency.
I thought the receive frequency was (chx)MHz + 1.64MHz, and ICM confirmed it.
but ordering the freqs calculated and I get nothing.

Does anyone have the correct formulae to get the right CB crystals for this old rig?


Top
 Profile  
 
 Post subject: Re: What Crystals are used in the Gonset G-12 Communicator C
PostPosted: Nov Sat 26, 2016 1:31 am 
Member

Joined: Apr Thu 12, 2007 3:24 am
Posts: 984
Location: Milwaukee,WI
For starters, the radio has an I.F. of 1650khz so your ( freq+1640khz ) crystals are going to be off frequency. Its been a bunch of years since I bought and sold old CB radios so I'm not sure if it was common practice to have the crystal frequency higher or lower than the incoming signal. You might have enough range in the I.F. cans to align them to 1640 and get your crystals to work on frequency.


Top
 Profile  
 
 Post subject: Re: What Crystals are used in the Gonset G-12 Communicator C
PostPosted: Dec Mon 12, 2016 3:22 pm 
Member
User avatar

Joined: Jan Thu 06, 2011 6:32 pm
Posts: 258
Location: Bethpage, NY
There is a book/guide out there from "CTS Knights" that listed all CB crystals from the 1950s-1970s, gave the complete specs on each mfg. CB and crystal required. Can't seem to find a copy anywhere, which would give the info I need.


Top
 Profile  
 
 Post subject: Re: What Crystals are used in the Gonset G-12 Communicator C
PostPosted: Dec Mon 12, 2016 10:13 pm 
Member
User avatar

Joined: Jan Thu 06, 2011 6:32 pm
Posts: 258
Location: Bethpage, NY
anyone know the difference between the CTS Knights F20S and S20S crystals? I really need to locate that CTS Knights book.


Top
 Profile  
 
 Post subject: Re: What Crystals are used in the Gonset G-12 Communicator C
PostPosted: Dec Tue 13, 2016 2:14 am 
Member
User avatar

Joined: Sep Wed 10, 2014 2:01 am
Posts: 1261
Location: Costa Mesa, California
https://www.amazon.com/Gonset-Citizens- ... B0011ENCWM

I didn't see any free sources for manuals. Hopefully this would have the crystal information.

Norm

_________________
KK6IYM


Top
 Profile  
 
 Post subject: Re: What Crystals are used in the Gonset G-12 Communicator C
PostPosted: Dec Tue 13, 2016 3:35 am 
Member
User avatar

Joined: Nov Sat 07, 2009 11:37 pm
Posts: 1693
Location: Sayreville, NJ 08872
Norm Johnson wrote:
https://www.amazon.com/Gonset-Citizens-Communicator-Instruction-Manual/dp/B0011ENCWM

I didn't see any free sources for manuals. Hopefully this would have the crystal information.

Norm


Actually the G-12 instruction manual doesn't have specific crystal information.

_________________
Pete, WA2CWA - "A cluttered desk is a sign of genius"
http://www.classicradiomanuals.com


Top
 Profile  
 
 Post subject: Re: What Crystals are used in the Gonset G-12 Communicator C
PostPosted: Dec Tue 13, 2016 4:15 pm 
Member
User avatar

Joined: Jan Thu 06, 2011 6:32 pm
Posts: 258
Location: Bethpage, NY
correct, which is why I need to find the CTS Knights crystal cross ref manual. it has the specs I need. Back in the days Gonset made their own crystals, so it was no issue.


Top
 Profile  
 
 Post subject: Re: What Crystals are used in the Gonset G-12 Communicator C
PostPosted: Dec Fri 30, 2016 9:26 pm 
Member
User avatar

Joined: Jan Thu 06, 2011 6:32 pm
Posts: 258
Location: Bethpage, NY
I was able to locate a Ch6 crystal of the F20S variety and it still won't receive on frequency. Anyone out there either know the correct crystals for this rig, or have a channel 6R? I can't believe it was this difficult to buy crystals for CBs and that so many variants were made for the same frequency channel. And Gonset gurus out there?


Top
 Profile  
 
 Post subject: Re: What Crystals are used in the Gonset G-12 Communicator C
PostPosted: Dec Sat 31, 2016 1:56 am 
Member

Joined: Apr Thu 12, 2007 3:24 am
Posts: 984
Location: Milwaukee,WI
When you say off frequency how far off? Close or way out of band? Is it actually firing up at all?

I'm assuming the crystal you bought from Ken is F20S 28.675mhz?

Are you sure the rest of the radio is aligned properly? If the I.F. section is not aligned properly your receiver will not work correctly.


Top
 Profile  
 
 Post subject: Re: What Crystals are used in the Gonset G-12 Communicator C
PostPosted: Dec Sat 31, 2016 3:18 am 
Member
User avatar

Joined: Jan Thu 06, 2011 6:32 pm
Posts: 258
Location: Bethpage, NY
When I try a transmit from a digital controlled cb, is is not heard at all, yet channels 1, 11 and 17 (all original Gonset crystals) it is heard. The two crystals I have are 28.6750 MHz, which is ch 6 (27.0250) plus 1.65MHz. I have a CTS Knights FSRS and F20S,neither even give a rushing sound when no signals are heard, unlike ch 1, 11 and 17 when I hear the rush. I even swapped around the crystals but the ch 6 still does not work. The other three are all 1.65MHz higher than base frequency. It is driving me crazy.


Top
 Profile  
 
 Post subject: Re: What Crystals are used in the Gonset G-12 Communicator C
PostPosted: Jan Sun 01, 2017 12:51 am 
Member

Joined: Apr Thu 12, 2007 3:24 am
Posts: 984
Location: Milwaukee,WI
Yeah that's odd. It sounds like 2 bad channel 6 crystals which would be unlikely but...

Do you have anything else to test the crystals in? Another radio or a checker? Or just as a last resort pop it into a transmit socket and see if it fires up. If your previous receive crystals transmit and your 2 new ones don't that would be a step closer to your problem


Top
 Profile  
 
 Post subject: Re: What Crystals are used in the Gonset G-12 Communicator C
PostPosted: Jan Sun 01, 2017 5:59 am 
Member
User avatar

Joined: Jan Thu 06, 2011 6:32 pm
Posts: 258
Location: Bethpage, NY
I got a set of channel 19 as well, transmits fine, which is freq/2. Receive, as I expected is dead. I can't believe all the receive crystals I bought are dead, in fact the last one I bought was guaranteed tested. It has to be something else, maybe these types, albeit the right frequency, somehow won't oscillate at the frequency this rig needs. I was hoping someone has the CTS Knights or Peterson crystal guides. I hate to have these custom made by ICM for $35 each, and then no guarantee those would work.


Top
 Profile  
 
 Post subject: Re: What Crystals are used in the Gonset G-12 Communicator C
PostPosted: Jan Wed 04, 2017 3:43 pm 
Member
User avatar

Joined: Jan Thu 06, 2011 6:32 pm
Posts: 258
Location: Bethpage, NY
Ok, the Crystal saga continues...

I purchased a CTS Knights A20S crystal at 27.025 MHz (exact CH 6 freq).
I receive the rushing sound!
BUT - when transmitting on a digital CB to CH 6, nothing is heard. I jumped up to CH 8, and it was loud and clear on the Gonset!

So, what exact crystals are needed for this rig (original question) :shock:

CH 8 is exactly 0.0300 MHz over CH 6, so do I need a 26.995 MHz crystal here?
26.995 + 0.0300 = 27.025 (CH 6)


Top
 Profile  
 
 Post subject: Re: What Crystals are used in the Gonset G-12 Communicator C
PostPosted: Jan Fri 06, 2017 5:13 am 
Member
User avatar

Joined: Nov Sat 07, 2009 11:37 pm
Posts: 1693
Location: Sayreville, NJ 08872
The manual states that the receiver crystal is an overtone type that oscillates at a frequency that is 1.65 MHz higher then the channel frequency. As you pointed out CH 6 is 27025 KHz. Add 1650 KHZ to it and the frequency is now 28675 KHz. That doesn't mean you can just go and buy any 28675 KHz crystal.

As an example, I pulled out a Ch 19 receive crystal I had in my box of assorted crystals. Ch 19 is 27185 KHz. The frequency marked on the crystal was 26730 Khz. The reason for this is that 27185 KHz - 26730 KHz = 455 KHz and that is the IF frequency for the receiver that is using this crystal. However, when I plug the crystal into my crystal tester and hang a frequency counter on the output, the measured frequency of the crystal is 8908 KHz. Overtone crystals are generally operated on the 3rd overtone. 8908 KHz X 3 = 26724 KHz. The marked frequency on the crystal is 26730 KHz. So 26730 KHz - 26724 KHz (measured) = 0.006 KHz difference, which after roughly 45 years of being manufactured, is close enough.

So, in your case for a Ch 6 receive crystal that is 1650 KHz higher then the operating frequency, you would need a an overtone crystal that's cut for 9558 KHz. 9558 KHz X 3 = 28674 KHz or if you want to get even closer, an overtone crystal cut for 9558.3 KHz (9558.3 KHz X 3 = 28.674.9 KHz). Generally 9558 KHz should be close enough since the more precise you get, the higher the cost to fabricate might be. It depends on the manufacturer. If you talk with a manufacturer, you can say you need an overtone crystal for 28675 KHz. 28675 KHz / 3 = 9558.33 KHz.

_________________
Pete, WA2CWA - "A cluttered desk is a sign of genius"
http://www.classicradiomanuals.com


Top
 Profile  
 
 Post subject: Re: What Crystals are used in the Gonset G-12 Communicator C
PostPosted: Jan Mon 09, 2017 3:31 pm 
Member
User avatar

Joined: Jan Thu 06, 2011 6:32 pm
Posts: 258
Location: Bethpage, NY
Manualman, as always, many thanks for your technical insight and recommendations. I have ordered a 3rd overtone crystal at 28675 KHz (as advertised) at the "pay" site; although it is in a different format (HC-25/U over HC-6/U). If this works, I can open one of my bad HC-6/U crystals and fit it inside the case, then epoxy it closed. This G-12 is an "oddbird" with the crystals, but I guess back in the 60's and 70's there were several mfgrs to choose from. Will let you know how it works.


Top
 Profile  
 
Post New Topic Post Reply  [ 15 posts ]  Moderator: Sandy

All times are UTC [ DST ]


Who is online

Users browsing this forum: KA8GEF and 10 guests



Search for:
Jump to:  




















Privacy Policy :: Powered by phpBB