The AM Forum

I am looking at buying a KWS-1 for AM. I can't not find any info regarding the AM bandwidth. Not even listed in the Collins manuals. I know it stated one sideband with carrier. Also, 455 or 500 kHz bandwidth mechanical filter.

The mechanical filter FL101 is 3khz wide and center frequency is 250 khz. So on SSB they will probably set the carrier point for a overall response from 300hz to 3300hz. If it was mine, I would set it from 100 to 3000hz and it will sound very nice on SSB with a decent mic and EQ if it is stable enough frequency wise.

On AM is going to be 3 khz wide and those collins mechanical filter have excellent shape factor, so AM is going to be narrow and restricted. I guess you could bypass the filter on AM with a switching board or get a wider filter and switch that in on AM for bandwidth control. Another idea would be to build a solid state low level modulator and relay switch it in line after the filter and feed the 1st mixer V201. That would be easy to implement and would work well on producing high quality AM, that's what I would do.

You could mount the modulator in a external box, separate power supply. All you would need is a coax from the internal balance modulator oscillator to supply the 250khz carrier to the new solid state modulator and coax right back in to the mixer V201. Tap in the the audio tube too run that in and out. Carrier control, mic gain, switching in the external modulator box too. No hacking of the transmitter and can be easily converted back. I used that same arrangement when I modded my Icom 756pro.

I found a 10kHz wide filter and also found out the filter is 250kHz center frequency. I only want to use the KWS-1 on AM. Although 10kHz is a bit wide on AM my D-104 will only pass 6kHz. Thanks.

Hey James

I live right down the road from you in Dunnellon. I been getting into AM a lot these days. Are you active on AM ?? I been on 3885 quite a bit. Let me know, we can make a schedule. I like to hear that Collins when you get it going.

John

Hi John. I been trying to put an AM station together. I bought four 'working' per sellers AM transmitters from hams and none worked. Lost of crooks out there. I complained on another site and an old friend came forward and sold me a tested and working Elmac AF-67. I have a Hallicrafters power supply and will be connecting it soon. Then this local to me KWS-1 came up and I jumped on it for only $500. And, seller gave me $200 of new tubes I will sell. KWS-1 net to me will be $300. So, off goes the Elmac AF-67 and I will get the KWS-1 working. Only 500 KWS-1 were built and cost in the 1950s was $2K. I be pleased to contact you.

Ok sounds good, I'm on 3885 right now 5:37PM  I been doing some testing. Looked you up on QRZ you have a Yaesu FTDX10 to get on AM ??

Welll I could use the FTDX-10 on AM. I have not used it for a year. Only used it a few times. I do not have interest in SSB, but want a good SSB radio on hand.

The FTDX10 has great audio on AM. I'm in the process of fixing my Amplifier, so I can only run 35 watts but my dipole is up fairly high so I sure you will hear me fine. You should get on SSB there is a big group locally in FL that talk all night, just about every night and have lots of fun. Anyway I'm listening on the 3885.