Can a Collins KWM-2A be set up for 60M? - BoatAnchors Forum at eHam.net

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eHam.net Forum : BoatAnchors : Can a Collins KWM-2A be set up for 60M?

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RE: Can a Collins KWM-2A be set up for 60M?	Reply
by K5MYJ on November 26, 2004	Mail this to a friend!
The above statment about the dial accuracy of the Collins riggs is correct. But they must be checked against WWV as they are analog oscillators. I was at Collins in 1966 and I was introduced to the technician that alaigned the PTOs. He was blind and did it all from feel and hearing. I think it was matched against the reference evey 10KHz. Bob Macklin K5MYJ/7 Seattle, Wa. "REAL RADIOS GLOW IN THE DARK"

RE: Can a Collins KWM-2A be set up for 60M?	Reply
by AE6RV on November 26, 2004	Mail this to a friend!
Bob, Everything must be checked against WWV, though I wonder if people do. Just because it has a digital readout doesn't mean it's right. I check my 100KHz Calibrator against WWV every few days. It's usually not off more than a few Hz. Bob

RE: Can a Collins KWM-2A be set up for 60M?	Reply
by K5MYJ on November 26, 2004	Mail this to a friend!
I use a Heath SB-301/SB-401 pair. They are similar to a Collins S-Line pair. The design is similar wirh the exception that they use crystal filters rather than a mechanical filter. The Heath units have an adjustable marker line on the dial that you zero with WWV. In 2 years I have not had to adjust mine. I don't have a clue what the riceboxes use. I know my 2m FM units have to way to calibrate. But my old Heath 2M Pawnee and 6M Shawnee can be calibrated close enough that you know you are in the band. But they were never intended to have the accuracy of the Collins gear. The Heath LMO is very similar to the Collins PTO. And like you my 100KC calibrator probably has more drift than the LMO. The problem with converting the KWM may be in the spurious products generated by the hetrodyning. Both Collins and Heath did an extensive study of possible birdies when the selected their IF frequncies. Bob Macklin K5MYJ/7 Seattle, Wa. "REAL RADIOS GLOW IN THE DARK"

RE: Can a Collins KWM-2A be set up for 60M?	Reply
by AE6RV on November 26, 2004	Mail this to a friend!
"The problem with converting the KWM may be in the spurious products generated by the hetrodyning. Both Collins and Heath did an extensive study of possible birdies when the selected their IF frequncies." I used an SB-102 for many years, so I know what you're talking about. The KWM-2A has a second crystal deck into which you plug crystals for additional frequencies. There's no conversion involved. As I noted earlier, the issue of spurious frequencies was well researched by Collins, and they issued a definitive SIL about it. Bob

RE: Can a Collins KWM-2A be set up for 60M?	Reply
by AH6GI on December 23, 2004	Mail this to a friend!
I have both S-lines and Heathkit SB's. I repaired and cleaned an LMO from a Heathkit SB-303 Just as an experiment, I put the LMO on a frequency counter for a week. It drifted less than 200 cycles throughout the day as the temperature rose and fell. After a week, it ended up 20 Hz from where it started. A good S-Line or SB-line is accurate enough for 60 meters. Consider that the SB-303's crystal calibrator emits 25 kHz markings. That means any reading on the analog dial is less than 12.5 kHz from a crystal reference that is traceable back to WWV. de ah6gi/4

RE: Can a Collins KWM-2A be set up for 60M?	Reply
by AE6RV on December 31, 2004	Mail this to a friend!
I put in a crystal that was for around 5.3MHz, and found a very large birdy from the PTO second harmonic. After drawing several charts, it appears that the best crystal for 60M would be 8.355 MHz. This would give you coverage from 5.2-5.4 with no worry of that birdy. Fortunately, a properly adjusted PTO gives you about 7Khz overrun on both ends, so this crystal would also give you the 5.4035 channel. After reading up more on 60 Meters, I've taken to heart the necessity for being exactly on channel. So, yes, I think you should use a digital readout. I plan to get the one from aade.com. Bob

RE: Can a Collins KWM-2A be set up for 60M?	Reply
by K1DA on May 27, 2005	Mail this to a friend!
I have an S 1 line on 60. The Collins Collectors Association site has posted the Collins Tech notice which indicated that operation on the center freq's we are given is OK. Several posts here have made that clear. Read them. BTW to get full output from an S line or M2 on 60 you must readjust the tuning caps normally used to peak 80 meters Since you don't need full output on 60 unless using an antenna which is below a dipole in "gain" it isn't difficult to get enough output on 60 and still get full output on 80. Having grown up using analog radios I find the tuning on a S line receiver when used with the calibrator 0'd to WWV puts me so close that when a QSO starts my rx is right on freq. The dither digital radio users get into when their displays don't agree on a mode like SSB where there is no reference carrier is byeyond me.

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