[VHFcontesting] DEMI 222 help

[David Olean]

Definitely put a fan on the heatsink. It will moderate heat buildup 
inside the unit and reduce any drift with digi modes. I use a small 12 
volt muffin fan mounted about 1/2" above the heatsink fins. I also put 
styrofoam baffles in around the crystal to delay any drift from 
temperature extremes.  My unit is now very stable on 222 for JT65 etc. 
No real drift at all.

Dave K1WHS

On 1/5/2022 1:00 PM, Ethan Miller K8GU wrote:
> Bill, et al,
>
> Thanks!  That is the right manual.  Not sure how I missed it before.  I
> think I have everything I need...thanks to everyone who replied on the list
> and direct.
>
> See you on the bands (and 222 when I get there)...
>
> 73,
>
> --Ethan, K8GU.
>
>
> On Wed, Jan 5, 2022 at 12:57 PM Bill Olson <callbill at hotmail.com> wrote:
>
>> Ethan, the DEMI instruction manual for that transverter is online here it
>> is for the "kit" version: vhflna doc (netsolhost.com)
>> <http://01895fa.netsolhost.com/PDF/Manuals/222-28_677.PDF> This has all
>> the info on the high power and low power IF drive options..
>>
>> The M67712 is pretty robust.. I suspect it will be just fine when run at
>> the output level you need for the Larcan..
>>
>> bill, k1DY
>>
>>
>> ------------------------------
>> *From:* VHFcontesting <vhfcontesting-bounces+callbill=
>> hotmail.com at contesting.com> on behalf of Ethan Miller K8GU <ethan at k8gu.com
>> *Sent:* Wednesday, January 5, 2022 3:11 AM
>> *To:* VHF Contesting <vhfcontesting at contesting.com>; Midwest VHF/UHF
>> Society Mailing List <mvus-list at lists.febo.com>
>> *Subject:* [VHFcontesting] DEMI 222 help
>>
>> All,
>>
>> I acquired an old DEMI 222-28 transverter from the K8CC estate last summer
>> and I'd like to get it rolling for the spring/summer contests (I have to
>> beam through "Mount Kettering" to get to the center of 222 Tuesday nights
>> from my home QTH and biggest amp I have for 222 is a 60-watt Larcan
>> pre-driver).
>>
>> This unit has the M67712 hybrid as the PA and does not seem to match any of
>> the legacy schematics found on (the current) DEMI web site.  It's wired for
>> common-IF with what looks like an attenuator for high drive power.  Do I
>> need to know anything special about converting it to low-drive split-IF to
>> work with my K3 and K2 (and TS-930S)?  Or can I just remove the
>> attenuator/switching board and run coax straight from the rear panel
>> connectors to the RXIF and TXIF pads on the board?
>>
>> Also, any experience or opinions about using the M67712-based transverter
>> on digital modes?  Muffin fan?  Low power?  Both?   I've been off the bands
>> above 6m the past couple of years since I moved from FM19 to EM79; but, if
>> my experience on 6m and the kvetching on the reflectors are any indication,
>> I'll need to spend some time on FT8.  I'm sure the Larcan pre-driver will
>> be fine at high duty cycle.
>>
>> Thanks/73,
>>
>> --Ethan, K8GU.
>>
>>
>> --
>>
>> https://na01.safelinks.protection.outlook.com/?url=http%3A%2F%2Fwww.k8gu.com%2F&data=04%7C01%7C%7C3bfbe71d726446156f9208d9cff9188e%7C84df9e7fe9f640afb435aaaaaaaaaaaa%7C1%7C0%7C637769491037981918%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C3000&sdata=%2FPIRuek1rp1milzVS93tsLDMIJ%2Fzm8fXCovoiSP1nHY%3D&reserved=0
>> Repair.  Re-use.  Re-purpose.  Recycle.
>> _______________________________________________
>> VHFcontesting mailing list
>> VHFcontesting at contesting.com
>>
>> https://na01.safelinks.protection.outlook.com/?url=http%3A%2F%2Flists.contesting.com%2Fmailman%2Flistinfo%2Fvhfcontesting&data=04%7C01%7C%7C3bfbe71d726446156f9208d9cff9188e%7C84df9e7fe9f640afb435aaaaaaaaaaaa%7C1%7C0%7C637769491037981918%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C3000&sdata=drRKLkxJeLp6rY53Pal2v4gqdUc7ETFpep%2BT%2Ff7kd1U%3D&reserved=0
>>
>