[MRCA] Recrystalling a TBX-8

Mon Mar 13 23:40:49 EDT 2017

Hi Rob, 

You are correct, except that the TBX-8 has a 3-tube transmitter. Oscillator (3A4), Modulator (3A4) and Power amp (2E22), …and, if you read the manual, they say it’s really a four-tube transmitter, with the 4th tube being a neon bulb for CW side-tone generation.  Whatever… 

But yes, it lends one to believe that an FT-243 would be fine in the 3A4 oscillator, and that the giant crystals are just a vestigial element of the original TBX design.   

At any rate, I’ll be finding out real soon.  Fortunately, I have some sacrificial crystals to test with before I plug in any good ones.   I so agree on not really needing crystals, except actually I don’t entirely agree. I found out the hard way during our Secret City Special Event Station last year, that while setup with lots of busy activity from the public, National Park Service, and other hams, and then a large WWII reenactment around us, well I discovered that once all of that action-packed excitement hits, with the soldiers and vehicles and artillery and stuff, …well I kind of forget how to work the radios.  Things like crystal calibration points, charts, and netting to other stations and things just seem to vanish and I’m left staring at the radio.  So, I’m thinking that switching to a crystal and netting the receiver to it should be easier.  At least I think it would be.  At any rate, I have a lot of crystals, so I’m going to try it and see. 

Thanks for the thoughts and advice. 

Garret

W8BUG

From: Rob Flory [mailto:farmer.rob.flory at gmail.com] 
Sent: Monday, March 13, 2017 5:38 AM
To: Garret Scott <scottgs at bellsouth.net>; mrca <mrca at mailman.qth.net>
Subject: Re: [MRCA] Recrystalling a TBX-8

Hi Garret,

Doesn't the TBX-8 have a 2-tube transmitter, unlike the earlier models with the single 837?  The characteristics would be quite different.

I never really found any advantage to operating the earlier TBX on crystal control.

Rob

On Mon, Mar 13, 2017 at 12:15 AM, Garret Scott <scottgs at bellsouth.net <mailto:scottgs at bellsouth.net> > wrote:

Hi Al,

Yes, those crystals are really scary. They would seem more appropriate in
Frankenstein's lab than a portable radio.

Thanks for the input.  That's exactly what I was thinking about.  I don't
want to destroy perfectly good (and soon to be rare) 80m ham band crystals.

Garret
W8BUG

-----Original Message-----
From: MRCA [mailto:mrca-bounces at mailman.qth.net <mailto:mrca-bounces at mailman.qth.net> ] On Behalf Of Al Klase
Sent: Sunday, March 12, 2017 8:13 PM
To: Military Radio Collectors Association
Subject: Re: [MRCA] Recrystalling a TBX-8

Hello Garret,

I played with one of those years ago, and was kind of freaked out by the
crystals, they're big, and appear to be heat sinked to the chassis.
Fearing that it might be the kind of oscillator that breaks crystals,  I
installed a # 49 pilot lamp ( 2 volts, 60 mA) in series with the crystal,
and used FT-243's without a problem.

YMMV,
Al

On 3/12/2017 5:52 PM, Garret Scott wrote:
> With all this crystal talk, I've been prompted to think about crystals
> for the TBX-8.
>
> Any one experienced with this or with those funky giant round
> CG-40024-A crystal holders which they use?
>
> Just wondering if a typical fundamental crystal on 3885 Kcs will go in
> there and work.
>
> Thanks,
> Garret
> W8BUG
> scottgs at bellsouth.net <mailto:scottgs at bellsouth.net> 
>
>
>
> ______________________________________________________________
> MRCA mailing list
> Home: http://mailman.qth.net/mailman/listinfo/mrca
> Help: http://mailman.qth.net/mmfaq.htm
> Post: mailto:MRCA at mailman.qth.net <mailto:MRCA at mailman.qth.net> 
>
> This list hosted by: http://www.qsl.net Please help support this email
> list: http://www.qsl.net/donate.html

--

Al Klase - N3FRQ
Jersey City, NJ
http://www.skywaves.ar88.net/

______________________________________________________________
MRCA mailing list
Home: http://mailman.qth.net/mailman/listinfo/mrca
Help: http://mailman.qth.net/mmfaq.htm
Post: mailto:MRCA at mailman.qth.net <mailto:MRCA at mailman.qth.net> 

This list hosted by: http://www.qsl.net
Please help support this email list: http://www.qsl.net/donate.html

______________________________________________________________
MRCA mailing list
Home: http://mailman.qth.net/mailman/listinfo/mrca
Help: http://mailman.qth.net/mmfaq.htm
Post: mailto:MRCA at mailman.qth.net <mailto:MRCA at mailman.qth.net> 

This list hosted by: http://www.qsl.net
Please help support this email list: http://www.qsl.net/donate.html

-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://mailman.qth.net/pipermail/mrca/attachments/20170313/69b2a51a/attachment.html>