[Boatanchors] Seeking Transmitter Design Suggestions

Sat Nov 20 16:54:48 EST 2021

What the heck happened to my formatting????  LOL

WayneWB4OGM

-----Original Message-----
From: hwhall at compuserve.com
To: brianclarke01 at optusnet.com.au <brianclarke01 at optusnet.com.au>; whitebear1122 at comcast.net <whitebear1122 at comcast.net>; ranickels at gmail.com <ranickels at gmail.com>
Cc: boatanchors at mailman.qth.net <boatanchors at mailman.qth.net>
Sent: Sat, Nov 20, 2021 2:32 pm
Subject: Re: [Boatanchors] Seeking Transmitter Design Suggestions

>The HT and the bias supplies are both Voltage-doubler designs, ie, half-wave rectification.<
For the record:
The HP-23 & HP-23A manuals say of the HV secondary circuit: "a full-wave voltage doubler rectifying circuit".Of the low voltage (not bias) part, "a half-wave voltage-doubler rectifying circuit".
The HP-23(A) schematics for the HV circuit match with the full-wave voltage doubler described here:https://www.electrical4u.com/voltage-doubler/The HP-23(A) schematics for the LV circuit match the half-wave doubler described there.
The Bias circuit in the HP-23(A) is a simple halfwave (no doubling) with RC filtering.
WayneWB4OGM

-----Original Message-----
From: Brian Clarke <brianclarke01 at optusnet.com.au>
To: 'wa9wfa' <whitebear1122 at comcast.net>; ranickels at gmail.com
Cc: boatanchors at mailman.qth.net
Sent: Fri, Nov 19, 2021 5:13 am
Subject: Re: [Boatanchors] Seeking Transmitter Design Suggestions

Hello folks,

Just be careful of the Heathkit HP-23. The HT and the bias supplies are both Voltage-doubler designs, ie, half-wave rectification. Both supplies use 125 uF 450 V smoothing capacitors. The HT supply has no choke. So, regulation of the HT supply will be pretty woeful. Further, after all this time, the electrolytics are likely to have quite high ESR, or may have dried out altogether. Think about where you can get new replacements for such capacitors.

Having two half-wave rectifiers increases the effective DC going back into the mains. Your local electricity supply authority may not like DC going back into the mains. You may assert that transformers cannot produce DC; but I suggest you do your homework on transformer-fed half-wave rectifiers.

To claim that Voltage-doubler designs are bullet-proof is very close to what follows male bovine creatures around. Leaving diodes in HV circuits without equalisation resistors is asking for trouble.

I suggest you get a different mains transformer and use full-wave rectification, particularly for the HT supply. Adding a choke will improve the regulation.

What do I like about the HP-23? The chassis and the case have room for making a proper power supply.

73 de Brian, VK2GCE

-----Original Message-----
From: boatanchors-bounces at mailman.qth.net [mailto:boatanchors-bounces at mailman.qth.net] On Behalf Of wa9wfa
Sent: Friday, 19 November 2021 2:33 PM
To: ranickels at gmail.com
Cc: boatanchors at mailman.qth.net
Subject: Re: [Boatanchors] Seeking Transmitter Design Suggestions

Hi Bob (and list), Thanks for your transmitter tube suggestions.  I’ve been to Latta’s page before looking at his 2x6 receiver.  Wow talk about a through discussion of that tube.

Your HP-23 power supply advice sounds great to me.  I was thinking of building an external supply but on second thought I like the idea of the HP-23A/B better.  I don’t have any transmitter building experience so I’d rather not take on a power supply as well.  

BTW, I know you are a big WRL DuoBander 84 fan.  I have one in great shape with the matching power supply that I will be working on this winter. It can be seen on my QRZ.COM page.  What a beauty!

73, Scott WA9WFA

> On Nov 18, 2021, at 2:14 PM, Robert Nickels <ranickels at gmail.com> wrote:
> 
> In case you're wondering why the 6AG7 is so often used/suggested for the osciallator stage, read this:
> 
> https://www.frostburg.edu/personal/latta/ee/6ag7amp/6ag7tube/6ag76ag7tube.html
> 
> The 6CL6 is a miniature version with similar specs.
> 
> And a suggestion - find a Heathkit HP-23 series power supply. Being a voltage doubler type they are nearly bulletbroof in comparison with those using high voltage secondary windings that are apt to fail,  and they will power most any AM/CW or SSB rig you might have.  I like the A or B versions that have the front-panel switch to select 250 or 300VDC for the low voltage, but they all can be wired to either internally.  It's a great universal power supply.
> 
> 73, Bob W9RAN

______________________________________________________________
Boatanchors mailing list
Home: http://mailman.qth.net/mailman/listinfo/boatanchors
Help: http://mailman.qth.net/mmfaq.htm
Post: mailto:Boatanchors at mailman.qth.net

List Administrator: Gary Harmon, K5JWK
** For Assistance: gharmon at idworld.net **

This list hosted by: http://www.qsl.net
Please help support this email list: http://www.qsl.net/donate.html
Message delivered to brianclarke01 at optusnet.com.au 

______________________________________________________________
Boatanchors mailing list
Home: http://mailman.qth.net/mailman/listinfo/boatanchors
Help: http://mailman.qth.net/mmfaq.htm
Post: mailto:Boatanchors at mailman.qth.net

List Administrator: Gary Harmon, K5JWK
** For Assistance: gharmon at idworld.net **

This list hosted by: http://www.qsl.net
Please help support this email list: http://www.qsl.net/donate.html
Message delivered to hwhall at compuserve.com 
______________________________________________________________
Boatanchors mailing list
Home: http://mailman.qth.net/mailman/listinfo/boatanchors
Help: http://mailman.qth.net/mmfaq.htm
Post: mailto:Boatanchors at mailman.qth.net

List Administrator: Gary Harmon, K5JWK
** For Assistance: gharmon at idworld.net **

This list hosted by: http://www.qsl.net
Please help support this email list: http://www.qsl.net/donate.html
Message delivered to hwhall at compuserve.com 