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Author Topic: for the harvey wells group, my two TBS-50D's are working  (Read 216 times)

N4MQ

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for the harvey wells group, my two TBS-50D's are working
« on: April 25, 2022, 05:02:04 AM »

Having two allowed me to venture into converting one to 160 meters with great success.  I have wound a new tank coil on 3/4"PVC pipe with the ability to operate 160 80 and 40 meters.

Taps are at 6uH, 12uH and 24 uH for 160-80-40 meters.  The 160 -80 meter operation will be controlled by a russian vacuum SPDT relay to shunt the 160 meter portion of the coil.  When the 160 coil segment is in use the relay is opened and switches in an additional 130 pF cap on the tuning cap.  L4 needs an additional 100 pF for resonance, and that will have an additional relay to switch it in and out.

Since I have the 24 VDC available, I will be adding an internal relay to switch the keying line, as the 85+ volts on the key line / mic PTT line to reduce shock and mic switch degredation.

The audio section is really stunning and reports on the audio have been well received.

Enjoy, Woody N4MQ
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K4PF

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Re: for the harvey wells group, my two TBS-50D's are working
« Reply #1 on: April 26, 2022, 06:27:46 PM »


Hi,

Congratulations on your 160m mod.

I'm wondering if you could measure the output power on 6 and 2M on the unmodified unit.  I used one on 10m back in the mid-60's at my radio club.  I'm curious how much output an 807 can produce at VHF.  I remember being "surprised" by the d.c. on the final's plate tank.  A wake-up call for sure.

73,
Ed
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N4MQ

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Re: for the harvey wells group, my two TBS-50D's are working
« Reply #2 on: April 27, 2022, 04:36:19 AM »

The power OUT on 80 meters with 315 v on the rf choke and 120ma input is 15 watts.  I have no crystals and consider 6 and 2 meters impossibly weak to consider, and useless for operation in todays noise.  I love it for the awa activities and will focus on 160 - 80 - 40 meters am.  Addition of a solid state relay on the keying line to remove high voltage at the key is my next current project.

I did add small old school lamps for power-on and transmit indicators, which match the front panel.  Switching in the 160 meter relays are done by adding a jumper across the lower crystal pins on the front panel.  Wish decals were available to refurbish the front panels.

Enjoy, support Ukraine, and happy spring.  Woody
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