Date: Mon, 3 Jul 2000 15:45:48 -0700 From: gsurrency at juno.com Subject: Re: [[Elecraft] Low power indication on 160meters] This is still true. In recent kits, we have increased the size of C153 from 39pF to 68pF to improve the TX drive on 160m. R4 is also left out, since it was originally used to swamp the Q of the 160/80m band-pass filters to make them more broad on 160m. This also reduced drive a little bit, so we decided to leave R4 out and tune the 160m BPF at 1850kHz. The bandwidth is still great enough to permit full output across most of the 160m band, with just a little dropoff in output at the edges. Now don't everyone go out and make these changes if your 160m output is already satisfactory. Some kits were on the edge of the minimum drive needed on 160m, and these changes help prevent that possibilty. If C153 becomes too large, it reduces the carrier suppression due to more IF leak-thru, especially on 40m. 68pF was found to be a good compromise between sufficient drive and excessive IF leakage. In all of the kits I've repaired that had 160m adapters, they all were able to achieve 12-15 watts. Remember to align the 160/80m BPF at 1850kHz, using the least RF output that allows a good meter indication. I always use less than 1 watt of RF output when I do this. Adequate DC input voltage is also a factor for best TX efficiency, so use 13.8 to 14.4 volts for best results. And if you've wound T4 for the 5 watt level - don't expect to get 10-15 watts RF output on any band, especially 160m. If the RF output on 80 is good, then you must have a problem in the 160m BPF or 160m LPF sections. Go back and check the component values and toroid for correct type (and dare I say it?): Poorly Tinned Toroid Leads!!! :-) Some variation in TX output is to be expected between rigs, with different RF transistors, construction, and alignments. At 1800kHz and 28MHz, the TX strip begins to drop off a little due to transistor performance and design efforts to keep the TX strip stable. Hope this info helps. ++++++++++++++++++ Murphy Chesney wrote: > > Paul Erickson wrote: > I just tried my K2 for the first time on 160meters, and when I try > to tune up, I get a low power indication. and after the tuner is > done, the power indicator does not deflect at all. > > Anyone else run into this? All the other bands are fine. > -- > cheers, Paul - VA7NT (ex VE7CQK) - email: paule at sfu.ca > > Paul, there was a discussion on the reflector May 20 2000 from Gary Surrency > regarding "Question about R4" where the issue of low power on 160m came up. > Per Gary "I've found in several rigs that merely increasing C153 from 39pF to > 68-100pF is sufficient to bring up a low 160m TX output, even with R4 > installed... In difficult cases, R4 may still need to be removed, but be sure > BPF is well aligned first at about 1850kHz" ... I'm sure Gary will respond > individually when his e-mail gets caught up but this may give you something to > play with until then. Good luck my friend - Sandy/KB3EOF > Hi Sandy, Thanks for the reply. I suspect that my BPF is not aligned correctly, because the reciever noise on 160 is significantly less than it is on 80meters. Guess I missed something. - -- cheers, Paul - VA7NT (ex VE7CQK) - email: paule at sfu.ca +++++++++++++++++ From: "Sherman Banks (W4ATL)" To: "Pierre Fillinger" , Subject: RE: [Elecraft] K2 low power on 160 meters Date: Sat, 18 Jan 2003 08:27:52 -0500 Make sure you wound T4 right. Using 2 turns on the 3-4 winding will cause the problem you descibe. I know - cause I wound T4 wrong! GL es 73 de W4ATL -----Original Message----- From: elecraft-admin at mailman.qth.net [mailto:elecraft-admin at mailman.qth.net]On Behalf Of Pierre Fillinger Sent: Saturday, January 18, 2003 8:15 AM To: elecraft at mailman.qth.net Subject: [Elecraft] K2 low power on 160 meters Hello all, my K2 is drawing 2 Amps on 160 meters, for 2 W HF output, and I have the Hi cur alarm (3A) for less than 3 W output. I also notice that on 3.5 Mhz, current is 0.2- 0.4 A higher than on other bands for comparable power output. L3/L4 are peaked for max power output. Help is apreciated. 73 de Pierre / F5MOG ++++++++++++++ From: "Pierre Fillinger" To: Subject: Fw: [Elecraft] K2 low power on 160 meters Date: Sat, 18 Jan 2003 18:03:28 -0000 Thanks to W4ATL. Problem solved. I played around T4, as recommended by Sherman... and I found a bad solder on T3. 73/72 de Pierre F5MOG +++++++++++++++++