[Milsurplus] WTB: Hi Power Resistive (Dummy) Load (sort of OT)

[Peter Gottlieb]

Can't you rent one?  The test equipment rental place I used to use up in 
Massachusetts (in Woburn or Billerica?, was 15 years ago) had stuff like 
that.  Renting isn't cheap being 10% of list per month typical, but $440 
for a month of use will get your problem solved.

Peter


Christian R. Fandt wrote:
> Hi folks,
>
> I'm looking for a 50 ohm dummy load to repair and maintain an 
> industrial RF generator used to excite a 1 kW laser cutting system 
> (namely, a Trumph TLF 1000). I searched the usual suspects (Google, 
> e*ay, etc., including Fair Radio). Finally found one used equipment 
> outfit in California that lists several of them being available but 
> doesn't bother to take the time to reply to my price and delivery 
> requests. I'll try again, but . . .
>
> The ideal would be a brand new Bird 8931-115SC13 with an optional 7/16 
> connector installed (reference: 
> http://www.bird-electronic.com/products/product.aspx?id=625 ). 
> However, my friend who owns the shop that uses the laser almost passed 
> out after hearing the $4400 price. It would be used once to repair the 
> system and left setting until the next time, whenever that is. He just 
> spent over $5k to replace the final tube per conclusion of a 
> third-party laser cutting machine maintenance outfit. They reportedly 
> said that was the problem causing the too high reflected power (the 
> original problem that needs to be solved). Uh-huh! And the tech did 
> not even have a dummy load with him to check the RF generator's 
> performance and tuning after he came back to install the new tube. He 
> left it back at the shop (~700 miles away) because "he didn't think he 
> needed it".
>
> My task is to isolate the source of the high reflected power between 
> either the laser "resonator" (which is the laser itself), the RF 
> generator, or the coax cabling between the units and attack the 
> problem. Hard to know were to solve the problem without ruling out 
> portions of the system which are not the cause.
>
> Hence, my approach to these two groups for leads. You have been known 
> to be a wellspring of information over the years.
>
> The RF power output is 6.5 kW maximum at 13.56 MHz which means a 7.5 
> to 10 kW load is needed. The connector is the 7/16 type (reference: 
> http://www.amphenolrf.com/products/716.asp ) and I'd need to make an 
> adaptor of some sort between whatever load I find and the system under 
> test, if required. I work in a 2-way radio shop for my day job and I 
> should be able to find components to make that up. We only know of 
> loads available up to around 2 kW from all our sources; our typical 
> max TX power we ever get into is 100-125 watts, even for base stations.
>
> FYI: The 7/16 connectors are a DIN standard commonly used in Europe 
> for high power applications.
> FYI: 13.56 MHz is an unlicensed frequency assigned for use in 
> industrial applications.
>
> Please reply off list as this is not too on-topic.
>
> Thanks very much for your help!
>
> Regards,  Chris F.
>
> NNNN
>
> Christian Fandt,    Electronic/Electrical Historian
> Jamestown, NY  USA      cfandt at netsync.net
>         Member of Antique Wireless Association
>         URL: http://www.antiquewireless.org/
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