PureSignal Modification for 100D

[VK-JOE]

Would anyone know where I can find the original document named "PureSignalRFModification1.2.pdf" ?

It’s referenced in “External Relay Approach for Bypassing the HPF Board With Pure Signal” in w1aex’s web pages

Here is the Link to the above article ...

http://www.w1aex.com/anan/anan.html#relay

– but the refrenced "PureSignalRFModification1.2.pdf" link is dead.

Just asking in case you came across this in the past.

Thanks

[w-u-2-o]

Unfortunately that document was only hosted at the KC9XG Yahoo Group, which went away with all of the other Yahoo Groups when Yahoo discontinued that service. The KC9XG group was a splinter group off of the main Yahoo Group that came into existence because of some sort of rift that developed amongst a few people. AFAIK nobody did a proper job of archiving that splinter group. So the file would need to be obtained from someone who had downloaded it a long time ago.

However, all is not lost. You don't really need that document. The W1AEX page provides enough information, and we can redevelop whatever additional information you are seeking right here.

Basically, the modification involves moving the switching for external PureSignal feedback from the internal RF board to a separate RF switch. This modification mitigates the poor internal RF crosstalk problem inside the 100D.

Electrically the approach is dirt simple: remove the coaxial cable on Angelia J5, which is the RX1 input. Attach the output of an RF switch to Angelia J5. Attach the coaxial cable you removed from J5 (that comes from the RF board and which carries the normal RX signal) to one input of the switch, and attached the PureSignal feedback signal (from the coupler) to the other input of the switch, and arrange for the PTT signal drive the switch in the appropriate direction for RX and TX.

Mechanically things are not as simple. There are many ways to accomplish this modification.

The first thing to consider is what kind of switch will you use. It's HF, so you can get away with murder. Many people have used a simple relay as shown on the W1AEX page. You can use an MFJ-1707 (and I've done that!) My preference is to use a Dow Key SPDT coaxial switch (or similar), and that's how my 100D is currently set up. If the purpose of the mod is to get the best feedback signal, then using the best performing switch in terms of crosstalk and isolation is a good idea. The Dow Key stuff can be expensive, but you can often find good examples on eBay (I was lucky that way).

The second thing to consider is where the switch will be located. Some folks have built very small switches or fit Dow Key switches inside the 100D. Others have set them up externally (I went with an external setup).

If you choose to use an external switch, the next challenge is how to route the signals. Some folks have repurposed the transverter connectors because they don't want to permanently modify their chassis. Others (such as myself) have drilled the rear panel for additional SMA bulkhead connectors. This is totally up to you.

Lastly you'll need to arrange to drive the relay or switch. With the right relay or switch you can drive it directly from the PTT output on the accessory connector. Some switches may require more current than can be delivered by the PTT output, or you may simply want to provide a buffer driver to protect the Angelia board regardless.

Finally, you'll need to buy or make some short coaxial cables appropriate to whatever mechanical configuration you've decided upon. Short SMA cables are a dime a dozen on eBay and Amazon.

More detail on what I did is available here: http://wu2o.dyndns.org/wu2o_anan_helper.html

[Mike_N1JEZ]

PureSignalRFMosdification 1.2.pdf attached.

[w-u-2-o]

Thanks, Mike!

[VK-JOE]

@Mike_N1JEZ, @w-u-2-o

Mike , Scott Thank you for your kindly responses