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Subject: glowbugs V1 #113
glowbugs          Tuesday, September 16 1997          Volume 01 : Number 113


Date: Mon, 15 Sep 1997 07:55:54 -0400 (EDT)
From: EWoodman@aol.com
Subject: 1650Kc IF Can

I came across a neat little 3 tube superhet in my 1956 Radio Handbook that
I'm thinking about building. I have everything in the junk box except one
item. Where can you find a 1650Kc if transformer? I've pulled lots of 455's
and some 10.7's in the past but no 1650's that I can remember. Sometime in
the past I lost my box full of IF transformers so I can't check anyway. Can
anyone point me in the right direction?

Tnx   Eric  KA1YRV



Date: Mon, 15 Sep 1997 09:16:37 -0700 (MST)
From: Jeff Duntemann <jeffd@coriolis.com>
Subject: Re: 1650Kc IF Can

Eric--

I did a lot of dredging looking for exactly this, and came up empty; this
in fact led to a discussion we had here on the list about creating your own
IF transformers.

One of the possibilities is to create a crystal-based filter on your own
using microprocessor crystals in that same general vicinity.  1.8432 Mhz
crystals are very common, with the downside that it puts your IF inside
160.  I've seen 1.6 Mhz can crystals, but not in recent catalogs.  You can
create an extremely sharp IF this way, bang-on for CW work.  Several QST
articles have been published on creating crystal filters, tho mostly for
sideband elimination.  If all you want is a good sharp IF, I think two
crystals is more than enough.  If you can spare the bucks you can just
order them, but it would be great to find a source of cheap surplus
crystals from which IF filters could be made.

If you DO find a source of 1650kc cans, I'd love to get a couple myself.

- --73--

- --Jeff Duntemann KG7JF
  Scottsdale, Arizona

At 07:55 AM 9/15/97 -0400, EWoodman@aol.com wrote:
>I came across a neat little 3 tube superhet in my 1956 Radio Handbook that
>I'm thinking about building. I have everything in the junk box except one
>item. Where can you find a 1650Kc if transformer? I've pulled lots of 455's
>and some 10.7's in the past but no 1650's that I can remember. Sometime in
>the past I lost my box full of IF transformers so I can't check anyway. Can
>anyone point me in the right direction?
>
>Tnx   Eric  KA1YRV
>
>
>
>



Date: Tue, 16 Sep 1997 12:20:57 +1000
From: Murray Kelly <mkelly@powerup.com.au>
Subject: Re: 1650Kc IF Can

Would oscillator coils and/or antenna coils work? Add 455 to the 
top end of the BC band (1600 KHzes) and it is well above. 
Either tune with a smaller cap or screw out the slug.

Taps might be the problem, unless you tap in capacitatively.

Jeff Duntemann wrote:
> 
> Eric--
> 
> I did a lot of dredging looking for exactly this, and came up empty; this
> in fact led to a discussion we had here on the list about creating your own
> IF transformers.

******************************************************************
*        Murray Kelly vk4aok      mkelly@powerup.com.au          *
*      29 Molonga Ter. / Graceville/ QLD. 4075/ Australia        *
*                   ph/fax Intl+ 61 7 3379 3307                  *
******************************************************************



Date: Tue, 16 Sep 1997 10:29:02 EDT
From: km1h@juno.com (km1h @ juno.com)
Subject: Re: 1650Kc IF Can

On Tue, 16 Sep 1997 12:20:57 +1000 Murray Kelly <mkelly@powerup.com.au>
writes:
>Would oscillator coils and/or antenna coils work? Add 455 to the 
>top end of the BC band (1600 KHzes) and it is well above. 
>Either tune with a smaller cap or screw out the slug.
>
>Taps might be the problem, unless you tap in capacitatively.
>

J.W. Miller produced a few IF xfmrs that would work.
The  12-W1 is a 1400-1600KHz  input or interstage and the 12-W2 is a half
wave output xfmr. Either one could work at 1650KHz if you changed the
internal caps. 
The 1732 is listed as a 1650KHz IF for CB radios.
The 913-W1 is a 1500KHz input and interstage and the 913-W4 is the
output, again they can be modified for 1650KHz. 
The above are out of production but still show up at fleamarkets, etc. 

Another option is to use a toroid xfmr and miniature Arco style trimmer
caps. The formulas can be found in various handbooks and QRP manuals. 

GL....Carl   KM1H 



End of glowbugs V1 #113
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