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Title: Johnson Messenger 1 10 meters concersion Post by: iw5ci on December 12, 2019, 07:07:13 AM I have just bought a Johnson Messenger 1 on Ebay. I like those lunchbox American CB transceiver. Instead of using it on CB band, i would like to convert it to 10 meters AM band (29010 or so) and to increase the power from 3 to 10Watts as i remeber that there was also a 10W 10 meters version .
So, while i wait from delivery i would like to collect as much informations as possible for the conversion task. Need help! Title: Re: Johnson Messenger 1 10 meters concersion Post by: KK4YY on December 12, 2019, 09:12:38 AM For schematics, manuals, and such, look here:
http://www.cbtricks.com/radios/ef_johnson/messenger_1/index.htm (http://www.cbtricks.com/radios/ef_johnson/messenger_1/index.htm) The hardest part of your task will be finding a pair of crystals. The rest shouldn't be much more than re-tuning. Good luck, Don Title: Re: Johnson Messenger 1 10 meters concersion Post by: DMOD on December 21, 2019, 06:20:04 PM I have just bought a Johnson Messenger 1 on Ebay. I like those lunchbox American CB transceiver. Instead of using it on CB band, i would like to convert it to 10 meters AM band (29010 or so) and to increase the power from 3 to 10Watts as i remeber that there was also a 10W 10 meters version . So, while i wait from delivery i would like to collect as much informations as possible for the conversion task. Need help! I did a conversion on a Raytheon Raytel 4 channel unit. But don't expect 10W since those internal power supplies aren't up to the task. It is best to use a linear amp after the CB conversion. I had my crystals made by Quartslab in the UK. Phil Title: Re: Johnson Messenger 1 10 meters concersion Post by: kb2vxa on December 22, 2019, 02:29:11 PM I would worry not about QRP on 10M AM. Back in my CB daze before the band went to Hell in a hand basket and KMD7606 became KB2VXA I had quite a few QSOs with "Skipland" using the legal 4W RF output both ways and no extra ERP from a beam antenna. About the easiest chicken box I ever converted was a Hallicrafters CB3A. It was only a matter of re-tuning the RX front end and tweaking the "tunable receive", then putting the RX XTALS in the TX sockets and re-tuning the TX section.
The early single conversion sets are that easy, what isn't is finding TX XTALS for a set that uses 455KHz under RX injection. On the other hand besides 4 fingers and a thumb is using a VFO fed into a XMIT XTAL socket. That may be done easily without mashing up the rig, just solder the mini coax to the base broken off an old XTAL from the rig and plugging it in. On the third hand is tweaking a "slider" made by Siltronics to make it a 100% illegal chicken box, camawn. (The older AM Gangstas from 75M will remember camawn.) Title: Re: Johnson Messenger 1 10 meters concersion Post by: Steve - K4HX on December 22, 2019, 10:25:43 PM From 2012-14, I worked I5KAP several times on 10 meters AM. He was never running more than 5 watts.
Title: Re: Johnson Messenger 1 10 meters concersion Post by: w5rkl on January 01, 2020, 11:36:51 PM The Johnson Messenger 11 meter transceivers used receive crystals that were 455Khz "below" the receive frequency. For example, channel 1 is 26.965Mhz so the receive crystal would be 26.965 - .455 = 26.510Mhz. To receive 10 meter AM on say 29Mhz, the receive crystal is 28.545Mhz (29 - 0.455 - 28.545). The transmit crystal is the actual transmit frequency, no conversion or mixing is done in the transmit side. A Messenger 1 transceiver can be converted/moved up to 10 meters in about an hour, once the receive and transmit crystals are obtained. The only change required to have a Johnson Messenger 1 transmit and receive on 10 meter 29.0Mhz AM is to replace the receive and transmit crystals then perform the receiver front end alignment, leaving the IF stages alone followed by aligning the transmit section. No component changes are required. To achieve full output power, place a jumper across R52 or replace R52 with a jumper wire the retune the transmitter. The original 10 meter Johnson Messenger transceiver was the "Viking 10 meter Messenger". E.F. Johnson said it had "10 wats input" which is quite possible since R52, 3900 10 watt resistor was not used on 10 meters. Johnson installed R52 to lower the input power to 5 watts when the Messengers were on 11 meters. I have a few Johson Messengers on 10 meters A Johnson Messenger 1 A Johnson Messenger II A Johnson Messenger 202 single-channel Business band radio (a couple of front end components needed replacing) A Johnson Messenger 223 using an N3ZI DDS VFO and a universal single transistor RF amp to control both receive and transmit The crystal control synthesizer was disconnected and the VFO output was routed through a relay to the receive mixer in receive and the driver stage in the transmitter. I've worked both coasts, Canada, and Italy using nothing more than a simple 10 meter inverted vee up 28 feet without an amplifier. They all have about 5 watts output. No need for an amplifier when 10 meters is open. 73 Mike W5RKL https://www.w5rkl.com |