Cool Tuning Job – RFS Corporation WIJD862-06SSP 6-Channel 800 MHz Combiner

At DuplexerRepair.com, all tuning and service/repair jobs are taken seriously, but now and then an especially interesting item rolls into the lab for service. In this instance it was an RFS Corporation model WIJD862-05SSP 6-Channel, 800 MHz combiner. After retuning for a

RFS Corporation WIJD862-06SSP 6-Channel, 800 MHz transmitter combiner.

change of frequencies/channel for the client, this 83 pound beast is nicely outperforming the factory specifications. It’s a rather impressive piece of communications hardware, although I have found RFS equipment to perform well in every instance.

Even after taking a good lick, it performs as expected — and better

This one actually survived an apparent drop or impact to one corner of the box during shipment which had to be a pretty good “lick,” because it totally

The isolator mounting flange/handle showed evidence of a pretty good drop or hit during shipping, but the performance is still excellent.

bent one of the heavy gauge metal isolator mounting flanges (which doubles as a lifting handle.) Even after taking this hit, the combiner is performing great — better than factory specifications, in fact.

If you’d like to see for yourself just how well this thing performs, just click on this link to view the performance report which includes network analyzer graphs and photos of the unit and the mechanical damage which occurred during shipping.

Tuning one of these takes considerably longer than even a multi-cavity duplexer assembly, and it’s much more involved. But it’s actually a blast to do and it sure feels nice when you finish the work and see just how great it performs. Only thing is: after you move this heavy thing around it’s a bit tempting to add a line item to the client’s invoice — the cost of a trip to a chiropractor or a masseuse.

Much Ado About Isolators – Demonstration and Testing of db Products DB4613-1A

I often get asked “Do I really need to spend the money to purchase an RF isolator and have it tuned for installation on my repeater or transmitter? And, if so, why?” In this video, I demonstrate (and test) a db Products (Decibel Products) DB4613-1A isolator on a 100 Watt paging system, showing how the isolator protects the P.A. from high SWR (even full reflected power) in the event of broken, damaged, shorted, or disconnected feedline, damaged or iced-over antenna, etc. Just take five or six minutes to watch this video and you’ll fully see for yourself why an isolator is an excellent investment for your system. DuplexerRepair.com provides professional, precise tuning and testing of isolators, with quick turnaround and full testing — including a custom report showing the tuning and performance of your isolator when it’s finished.

Overhaul and Conversion of DB Products 4-Cavity Duplexers to 6-Cavity “B” Models

We’ve recently converted a couple of sets of Decibel Products (a/k/a/ dbProducts and dbSpectra) 4-Cavity 4060-WOC-C duplexers to 4062-WOC-B models. Translation:

4062-WOC-B Duplexer built by converting a new set of 4060-WOC-C cavities to “B” models, and overhauling and converting two additional “C” cavities from a failed set, resulting in a great working 6-cavity “B” model with over 100 dB of isolation in each branch.

we’ve converted 4-cavity sets which were built for operation at higher, public safety and commercial frequencies to 6-cavity sets which are optimized for operation in the 2-Meter Amateur Radio / ham frequency bands.

Doing so involves a fair amount of time and work, including total overhaul of each cavity, custom manufacturing of the correct length loops, capacitor replacements, and the building of a new frame for the expanded 6-cavity set, not to mention final tuning and performance testing.

Tuning Plunger Removal, Inspection, and Polishing

After disassembly of the old cavities, one of the many steps in the overhaul and conversion process involves getting the tuning plungers back in good

Aged, oxidized tuning plungers BEFORE cleaning and polishing.
The same two tuning plungers after careful cleaning and polishing.

shape. As can be seen in these photos showing the plungers before and after the application of some TLC, the difference is more than visible. So is the resulting performance and ability to be accurately tuned (and for that tuning to remain stable.)

Custom Copper Loop Fabrication and Loop Enclosure/Cavity Conversion

In order to obtain the best cavity SWR (lowest insertion loss) along with the maximum branch notching/isolation performance, the copper loops in one

Original capacitor with signs of excessive heating, old flux residue which had not been cleaned off after soldering, etc. This capacitor had failed, causing the set to be taken out of service.
New capacitor and custom made loop installed. The enclosure has been relabeled from the original “003” part number to its new, proper “005” designation.

branch of the duplexer assembly have to be replaced with loops of the correct length. At DuplexerRepair.com, we handcraft the replacement copper loops. We start with high quality, 30-mil copper and carefully cut, shape, drill, and polish the replacement loops.

During the installation of the new, replacement loops of proper dimensions for 2-Meter operation, we also replace the trimmer capacitors. This is actually a delicate process, as these capacitors do not tolerate excessive heat. It is quite common for us to discover signs of overheating from the combination of the original capacitor installation, soldering, and RF heating over time (mistuning, high SWR, and lightning will destroy these capacitors pretty easily.)

Frame and Mounting Rail Fabrication / Conversion

The original 4-cavity frame and mounting rails for assembling the cavities into a set have to be replaced in order to accommodate six cavities. We

Custom machined mounting and frame bars for conversion to 6-cavity set.
New custom made rails with cavity braces and clamps installed.

 

custom machine these from square aluminum tubing.

Reassembly, Cable Harness Inspection and Service, and Final Testing

With all the components overhauled and reassembled using the new frame and mounting rails, each cable, Tee-connector, etc. is inspected and cleaned

Another 6-cavity 4062-WOC-B set we recently converted, overhauled, and built, reassembled and ready for final tuning and testing.
Duplexer assembly being put through final tuning and performance testing and verification. The client gets a complete report of the testing, including the network analyzer graphs showing proof of performance.

or replaced as necessary.

Each cavity is then individually performance tested, followed by connecting each branch as a set and testing it, and finally the entire harness is secured and the entire set undergoes its final tuning and performance testing.

The End Results

A complete conversion, expansion, and overhaul job such as the ones described here, commonly involves between 15 to 20 hours of labor, plus

With 113.37 dB of isolation (factory spec is 100 dB or higher) with only 1.45 dB of IL (Insertion Loss (factory spec is 2.2 dB or less), this set is working considerably better than factory specifications. Well worth the investment of time, money, and energy.

materials. It’s not exactly cheap, but the results are worth it. What usually starts out as a 4-cavity 4060 “C” model (not built for factory spec operation in the 2-meter Amateur radio band, and often a set which has failed and been pulled from service) becomes a great working 4062 “B” model — as though it left the factory as a set intended to work to specs in the 2-Meter band. The 4-cavity 4060 models are rated at 80 dB or more of branch isolation; whereas the 4062 6-cavity sets are rated for 100 dB or higher isolation. At the typical 600 KHz “split” used in 2-Meter band, this extra isolation makes a world of difference, especially at transmitter power levels above 40 watts or so, and can be a game-changer when trying to get better performance out of certain repeaters, such as the Yaesu Fusion DR-1/DR-1X series, which tend to have lower receiver selectivity compared to most of the commercial grade repeaters with highly selective physical filtering on the front-end. Very often we deal with duplexers sent to the DuplexerRepair.com labs with complaints of “They worked great for years with our old Mastr II repeater running 40 Watts, but when we bought and installed a new Fusion repeater (or D-Star repeater, DMR  machine, etc.) everything went to crap.”

We deal with such all the time. And we’re here to help. Call or contact us if you’re experiencing similar problems. We’ll be delighted to help you get things working the way they should. As they say, “A chain is only as strong as its weakest link.” Duplexers which aren’t up to the task will result in a poor or totally useless repeater setup. It doesn’t have to be that way. We’re here to remedy that.

 

 

 

 

 

 

New “Flat Rate” Duplexer & Cavity Tuning Pricing Just Added To Our Website

We naturally get lots of telephone calls and emails asking how much we charge to tune duplexers and filters. In the interest of saving you time and getting  your equipment in, tuned, and back to you even faster we have a new page on our website with “flat rate” pricing so you can quickly determine what the fees will be. Note that these prices apply only to equipment which arrives in our lab in good working order with all necessary cables, connectors, adapters, hardware, etc. attached. Just click on this link to see view our Flat Rate Tuning Service Price List. Quick turnaround. Precision work. Excellent customer service. All at prices quite friendly to your equipment and maintenance budget.