From cbfsb!att!emory!wa4mei!ke4zv!gary Fri Jan 31 23:25:08 EST 1992 Article: 13433 of rec.radio.amateur.misc Path: cbfsb!att!emory!wa4mei!ke4zv!gary From: gary@ke4zv.uucp (Gary Coffman) Newsgroups: rec.radio.amateur.misc Subject: Re: Commercial xceivers (was Re: Ramsey kits) Summary: Tune up tips Message-ID: <1992Jan31.194232.12931@ke4zv.uucp> Date: 31 Jan 92 19:42:32 GMT References: <3220@cruzio.santa-cruz.ca.us> <14570260@hpnmdla.sr.hp.com> Reply-To: gary@ke4zv.UUCP (Gary Coffman) Organization: Gannett Technologies Group Lines: 67 In article <14570260@hpnmdla.sr.hp.com> alanb@hpnmdla.sr.hp.com (Alan Bloom) writes: >In rec.radio.amateur.misc, Mike_Beezley.houstoncssc@xerox.COM writes: > >>Last fall I decided to try my hand at the 2M transceiver. >>.... Everything went well until it came time >>to see if the thing would receive. I hauled out my HT and transmitted from >>about 50 feet away and it worked!. I then hung a J-pole onto the antenna jack >>and tuned it to a local repeater. Nothing! It didn't even begin to receive. >>I went back through all the steps and it was all correct. The only thing I >>couldn't be certain about were the alignment steps. You need a freq counter. >>The instructions warn you of that but believe them you _do_ need a freq >>counter. > >Either the receiver is off frequency, or the front end or IF (intermediate- >frequency amplifiers) are misaligned. If there is a frequency discriminator >output (test point) available, then just transmit on the HT and adjust the >crystal oscillator in the Ramsey synthesizer for zero volts on the test point. >If said test point is not available, then have someone talk into your HT >("Testing, 1, 2, 3...") while you listen on the kit, and adjust the >oscillator for lowest audio distortion. > >To adjust the front end and IF tuning, you need a weak signal. Maybe >move the HT to another room or transmit into a dummy load. Adjust each >stage for lowest noise (receiver unsquelched). As sensitivity improves, >you will have to reduce the incoming signal to get the noise back. Let me give you a few tips on aligning the Ramsey. Step one, ignore the procedure in the book. Step two, inject a 10.7 Mhz signal into the IF at L28 and adjust L24, L32, and L28 for best quieting. You'll need to reduce injection several times as you alternate back and forth among these coils. Now inject a 146.52 Mhz signal into the antenna input, or use whatever frequency you have set into the diode matrix. Now stretch L15, L26, and L27 for best quieting. Don't be surprised if you need to stretch the coils to twice their supplied length. You should be down to about .2 to .4 microvolts at this point. Now go back and repeak everything again with a .2 microvolt signal at the antenna. You should get at least 12 db quieting. The preceeding procedure assumes that you have already used a frequency counter to set the oscillators on frequency. If they don't come up within range, you'll need to add padder capacitors. Depending on whether you are high or low, you'll add 10 pf across the varactor or the crystal. Do this on the back side of the board with minimum leads. If 10 pf won't bring them in range, call Ramsey and demand new crystals. They *will* give you new crystals that will work. Now on to the fun job of aligning the transmitter. First make sure that you installed the chip capacitor *exactly* where Ramsey says to put it. THIS IS CRITICAL. Now carefully monitor current and place the unit in transmit. If the current fluctuates wildly, you've got a parasitic oscillation. Quickly adjust C47 and C52 to stop this. These capacitors should have been preset to the center of their range. Now monitoring output on a sensitive power meter, adjust C47 and C52 for maximum output. If the adjustment winds up at the end of it's range, compress or expand L14 or L17 until it comes into the center of it's range. You may have to actually remove or add a turn to these coils to get it right. Your power will likely be around 2 to 3 watts at this point. Now compress or expand L16 for maximum power. Again you may find that you have to subtract or add a turn to this coil. Go back and repeak C47 and C52. You should now have 5.5 to 6 watts out. If you have access to a spectrum analyser, use it during transmitter tuneup. This transmitter can be quite dirty at certain tuning settings. Adjust for cleanest output even if that drops your power out by half a watt or so. Gary KE4ZV