[Boatanchors] [Heathkit] GB> DX40 Function Switch Mod - WAS: Help locating a heathkit part

[Bill Mellema]

sbjohnston at aol.com wrote:
>  I'll send you scans of the DX-60 and DX60B schematics in a separate email...
>
> Steve
>
>
>  
>
>
>  
>
> -----Original Message-----
> From: Bry Carling <bcarling at cfl.rr.com>
> To: FLBOATANCHORS at yahoogroups.com; TampaBayTradersNet at yahoogroups.com; heathkit at mailman.qth.net; forsale-swap at mailman.qth.net; boatanchors at mailman.qth.net
> Cc: glowbugs at piobaire.mines.uidaho.edu
> Sent: Tue, 5 May 2009 4:25 am
> Subject: GB> DX40 Function Switch Mod - WAS: Help locating a heathkit part
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
> There IS another method which has been used in many DX60s.
>
>
>
>
>
>
> The DX60 seems to have suffered from this problem far worse than 
>
>
>
>
>
>
> the DX40s did - looking at how many have burned out anyway...
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
> Maybe guys were more careful back in the DX40 era?
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
> Anyway, what a LOT of guys have done is to install a small relay 
>
>
>
>
>
>
> to handle the HV switching which is the contact set that burns out 
>
>
>
>
>
>
> on the function switch. The best that I remember it, there is another 
>
>
>
>
>
>
> set of contacts which switches some lower voltage and you can tap 
>
>
>
>
>
>
> off that to power a 12V or 6V relay to handle the HV switching chore.
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
> I have not seen this mod written up anywhere, but I HAVE seen it installed in 
> at least two different DX60s. I expect the same scheme would work for a 
> DX40 also.
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
> These things have become a little tougher with the removal of 
>
>
>
>
>
>
> Heathkit manuals from the BAMA mirror site (sadly) after many years
>
>
>
>
>
>
> - thanks to lawyers.
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
> Most (NOT all) web sites have r emoved Heathkit manuals. Many have 
>
>
>
>
>
>
> even removed the modification information out of fear of the pests.
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
> I think I have a copy of the manual and schematic somewhere on 
>
>
>
>
>
>
> a CD but finding it could be a challenge!
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
> Does anyone else have those modification details that they would like to 
> share?
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
> http://www.heathkit-museum.com/ham/hvmdx-40.shtml
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
> http://www.qsl.net/la5ki/org/he/dx40.htm
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
> 73 de AF4K, Bry
>
>
>
>
>
>
> ?
>
>
>
>
>
>
>   
>> A suggestion on the DX-40 function switch... 
>>     
>
>
>
>
>
>
>   
>
>
>
>
>
>
>   
>> I don't think you'll find an exact replacement anywhere except a parts-unit DX-40 or DX-35. So I'd 
>>     
>
>
>
>
>
>
>   
>> suggest one of two approaches: 
>>     
>
>
>
>
>
>
>   
>
>
>
>
>
>
>   
>> 1) Build your own from switch parts. This requires some circuit analysis, but from what I can see 
>>     
>
>
>
>
>
>
>   
>> on the schematic, a five-position five-pole switch could do the job 
>>     
>
>
>
>
>
>
>   
>
>
>
>
>
>
>   
>> 2) Change thecontrol system of the rig to use available switches.The original control system is 
>>     
>
>
>
>
>
>
>   
>> very hard on thefunction switch, and is obviously a cause of failures. 
>>     
>
>
>
>
>
>
>   
>
>
>
>
>
>
>   
>> I prefer 2). The existing control switch has to do things like switch the B+ to the 6146 plate, which 
>>     
>
>
>
>
>
>
>   
>> makes for a short life. 
>>     
>
>
>
>
>
>
>   
>
>
>
>
>
>
>   
>> 73 de Jim, N2EY
>>     
>
>
>
>
>
>
>   
>
>
>
>
>
>
>   
>
>
>
>
>
>
>   
>
>
>
>
>
>
>   
>> Remember Mom this Mother's Day! Find a florist near you now. 
>>     
>
>
>
>
>
>
>   
>
>
>
>
>
>
>   
>> __._,_.___ 
>>     
>
>
>
>
>
>
>   
>
>
>
>
>
>
>   
>> TELL YOUR HAM FRIENDS ABOUT FL BA.
>>     
>
>
>
>
>
>
>   
>
>
>
>
>
>
>   
>> Post a message: FLBOATANCHORS at yahoogroups.com
>>     
>
>
>
>
>
>
>   
>> Subscribe:FLBOATANCHORS-subscribe at yahoogroups.com
>>     
>
>
>
>
>
>
>   
>> Unsubscribe: FLBOATANCHORS-unsubscribe at yahoogroups.com
>>     
>
>
>
>
>
>
>   
>> List owner: FLBOATANCHORS-owner at yahoogroups.com
>>     
>
>
>
>
>
>
>   
>
>
>
>
>
>
>   
>> http://groups.yahoo.com/group/FLBOATANCHORS
>>     
>
>
>
>
>
>
>   
> Steve & Gang:
>   
I am very familiar with the mod you speak of. I have a DX60B that had 
burned out contacts. It take work but you can replace the burned 
contacts with contacts of similar design from an old switch assembly. I 
screwed them in the ceramic body using very very small screws and nuts I 
obtained from a local optical store. They have them for repairing 
glasses frames. I installed a 12 VAC relay and use it to switch the B+ 
(High Voltage). The 12VA can be pulled off the filament chain. The real 
hassel is removing the function switch so you can get to the contacts to 
drill them out. I used a Dremel  tool  and a  good  small drill bit.

I have a DX40 I will be installing the mod in as well. With the relay 
switching the HV these rigs will run for many years to come.

Hope this help OM..

Best 73's

Bill N3WM

>
>
>
>
>   
>
>
>
>
>
>
>   
>
>
>
>
>
>
>   
>
>
>
>
>
>
>   
>> Your email settings: Individual Email|Traditional
>>     
>
>
>
>
>
>
>   
>> Change settings via the Web (Yahoo! ID required)
>>     
>
>
>
>
>
>
>   
>> Change settings via email: Switch delivery to Daily Digest | Switch to Fully Featured
>>     
>
>
>
>
>
>
>   
>> Visit Your Group | Yahoo! Groups Terms of Use | Unsubscribe 
>>     
>
>
>
>
>
>
>   
>
>
>
>
>
>
>   
>> __,_._,___ 
>>     
>
>
>
>
>
>
>
>
>
>
>
>
>
>
> ?
>
>
>  
>
> ______________________________________________________________
> Heathkit mailing list
> Home: http://mailman.qth.net/mailman/listinfo/heathkit
> Help: http://mailman.qth.net/mmfaq.htm
> Post: mailto:Heathkit at mailman.qth.net
>
> This list hosted by: http://www.qsl.net
> Please help support this email list: http://www.qsl.net/donate.html
>
> .
>
>