[Fourlanders] DCI Bandpass Filter - High Reflected Power

[Rogers, Ron]

I doubt you are going to find any physical flaws in the filter.

Those 4 stage helical chamber filters have been found to be sensitive to the capacitance variables introduced by the connecting coax leads. Be sure to try other coax jumpers.

With the way my amps are designed using a pair of external Dow Key relays, I've never been concerned with the SWR on DCI filters SWR over the years. I always insert them into the RX line only. 


Ron 
WW8RR

-----Original Message-----
From: fourlanders-bounces at contesting.com [mailto:fourlanders-bounces at contesting.com] On Behalf Of Brian McCarthy
Sent: Tuesday, September 07, 2010 9:27 AM
To: Fourlanders
Subject: [Fourlanders] DCI Bandpass Filter - High Reflected Power

I know that we have had occasional problems with filters used for the contests. My DCI-223.5-3H has developed a problem. With 30 watts in at
222 MHz I get 10 watts returned. I have opened up the unit. I found no obvious problems. I closed it back up, but made sure to carefully clean the center contacts on the SO-239's (MEK and cotton swabs). No change. I guess I will open it up again and check for hairline fractures, or bring it to work where I can reheat the joints with one of the monster soldering irons.

One added data point of information, I NEVER feed the output of the amp through the filter. I always use it between the transverter and the Lunar Link.

Does anyone have any other suggestions?

When we had trouble before with DCI filters, what were the failure modes?

Does anyone have a similar filter appropriate for 222 MHz that I could conveniently borrow?

Thank you!
Brian
NX9O
_______________________________________________
Fourlanders mailing list
Fourlanders at contesting.com
http://lists.contesting.com/mailman/listinfo/fourlanders