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Author Topic: Heathkit junk box  (Read 14258 times)
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rozradio
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« on: May 25, 2005, 08:00:25 PM »

Hi Gang fisrt time post:

I am interested in 80 M AM. I have a fair size Heathkit junk box from a few HW100-101 I've aquired.  I was wondering if it would be feazible to rework a 5.-5.5Mz VFO down to 3.5-4.0 Mz for AM and CW. followed by the usuall Buffer /Driver/ Final Stages. Would it be stable enuff? And will Driver/Final G1 Modulation do the trick, I do not have any plate /Modulation Transformers on hand


Thankyou .....VA3VJC/Richard
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w3jn
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« Reply #1 on: May 26, 2005, 06:56:39 AM »

AM doesn't need quite the stability that SSB does.  At any rate, the heathkit VFOs should be more than stable enough.

There are a couple of ways you could do this.  You could convert the Heathkit VFO from 5 MHz to 3.5 MHz using some additional parallel cap(s) at the expense of tuning range and possibly stability.  Or you could use heterodyne xtals to convert to 80M.

If you have a more or less complete HW101, I suggest that you use the existing balanced mudlator, IF, etc., but bypass the crapstal filter.  Do a bit of work on the audio stages for wider audio response.  Disable the ALC, and you're done.  You should be able to get about 20-25W out of it with 120+% mudulation peaks.  Make sure you use a scope to monitor your output.  I did this with a Heathkit HW-20 mobile SSB xmitter and it works FB, driving a leenya amp.

Otherwise you could use screen mudulation and class C.  You'll get perhaps 40-50W out.

Let us know how it turns out!

73 John
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ve6pg
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« Reply #2 on: May 26, 2005, 08:26:31 AM »

WELCOME RICHARD...I SEE U R IN HAMILTON.HAVE YOU LISTENED TO OUR GROUP ON 3725KC? THERE IS A BUNCH OF US ON THERE,BILL VE3LVL,ST.KITTS,JOHN VE3LZ,HAMILTON,JIM VE3BRL,MISSISSAUGA,ETC.ABOUT 15 OF US..WE ALL RUN OLD AM GEAR,AND YOU ARE WELCOME ANYTIME...DO YOU HAVE AM CAPABILITY AT UR QTH? EVEN WITH 25WATTS FROM A RICE BOX,WE WILL HEAR YOU FB...SO,LET ME KNOW ABOUT YOUR SITUATION..SEE YA...TIM...SK..
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Glenn K2KL
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« Reply #3 on: May 26, 2005, 10:28:01 AM »

Hi Richard, welcome to AM

Rather than mod the Heath LMO, as John mentions, use it to build a heterodyne exciter (exactly what I'm doing) mix the 5-5.5mcs output from the LMO with a fixed xtal oscillator (8.5mhz for 80meters) This arrangement can give you multiband capability in addition to being an extremely stable signal source. Lowlevel modulate one of the following stages or high level modulate the final.



Quote from: VA3VJC
Hi Gang fisrt time post:

I am interested in 80 M AM. I have a fair size Heathkit junk box from a few HW100-101 I've aquired.  I was wondering if it would be feazible to rework a 5.-5.5Mz VFO down to 3.5-4.0 Mz for AM and CW. followed by the usuall Buffer /Driver/ Final Stages. Would it be stable enuff? And will Driver/Final G1 Modulation do the trick, I do not have any plate /Modulation Transformers on hand


Thankyou .....VA3VJC/Richard
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rozradio
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« Reply #4 on: May 26, 2005, 04:56:40 PM »

Hi again "

Thanx John, Tim, Glen for the replys and suggestions. I have 1 semi working HW-100, and 1 torn down. It was assembled rather poorly, so I'm starting over with that one.When I begin assembley  I will try the suggestions . I do not have AM cap. at the moment, or a proper 80 Xmit Antenna, and very little room for long wire. So I listen on 80.

The P/S I got with the working rig is home brew and it and the rig where in storage for 5 yrs , so P/S might be in need of Caps. So thatsa my station in a nut shell Smiley

73  VA3VJC/Richard
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Sam KS2AM
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« Reply #5 on: May 26, 2005, 06:41:10 PM »

Quote from: VA3VJC
Hi again "

I do not have AM cap. at the moment, or a proper 80 Xmit Antenna, and very little room for long wire. So I listen on 80.

73  VA3VJC/Richard


Richard,

If you can get a feedline over there without anyone noticing, there is plenty of room in Eastwood Park for dipoles, etc.    Oskee-wee-wee !


KS2AM (formerly of 539 Ferguson)
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WA1HZK
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WWW
« Reply #6 on: May 26, 2005, 06:58:45 PM »

OK, Carbon up the face, black "T" shirt, black pants, black knit cap & go for it. There is always a local guy with a bow & arrow to help you get an antenna up. That's your first step. Once you hear ths group on 75 you will either toss the radio out the window or join us and "Goon Squat". Welcome to 75.
Keith
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« Reply #7 on: May 27, 2005, 12:51:44 AM »

i have two Heath rigs i use on AM- an HW101 and an SB102. both are used as exciters only. i replace the crystal filter with a .001 cap, unbalance the balanced modulator to give about 15-20W carrier, short the ALC jack (must be done!) on the back panel, and i'm on the air with excellent AM.

    a few simple audio mods are in order here- in the speech amp change R2 to 6.8 meg, C2 to 47 mfd, C9 to .05mfd, C11 to.05mfd, and C13 to 10mfd LOW LEAKAGE nonpolarized electrolytic. if C13 is not stable, your carrier balance setting will drift. while you are in there replace the balanced modualtor diodes with new 1N4148 or similar being careful to match the forward and reverse resistance to get a matched set of four.

    the component designations (C2, R2 etc) for this mod are good for all HW100, HW101,SB101 and SB102 rigs. to operate, switch to CW or TUNE, load for max power out, then increase the loading until the output drops about 5-10%. switch to LSB, set the carrier balance pot to give about 15-20W carrier, and advance to mic gain until voice peaks just kick the wattmeter up a bit. best operation is done by monitoring with a 'scope (strongly recommended). if your audio is out of phase (scope shows no/low positive peaks) reverse the phase by unbalancing the carrier balance to the same output level, but at the other side of the null.
 for line level audio just couple direct to the high side of the mic gain pot through a .47 cap. done properly, fed with processed audio and carefully tuned these mods give audio that rivals the best you hear on the air. if you switch the crystal filter back in you will now sound darn good on sideband too.
somebody please print this mod and save it, or post it where it can be seen. i've had many requests for it
"happy motoring"
DE KD2XA
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w3jn
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« Reply #8 on: May 27, 2005, 06:54:18 AM »

I've heard Chris' SOB-102 on the air and it does indeed sound outstanding.

BTW my experience with these rigs indicates that all of the resistors should be checked as they are prone to drifting way out of tolerance.

73 John
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« Reply #9 on: May 27, 2005, 11:34:31 AM »

black is too "solid" a "color" for night work. U r better off with a green or a darker shade of gray... off the shelf "camo" is gud as it helps break up the shape of the human form... the  drawback is  when the LEO's ask you " why you walkin' around at night in camo and a bow/arrow eh??



                                           klc
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Jim, W5JO
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« Reply #10 on: May 27, 2005, 03:37:11 PM »

Quote from: KD2XA
to operate, switch to CW or TUNE, load for max power out, then increase the loading until the output drops about 5-10%. switch to LSB, set the carrier balance pot to give about 15-20W carrier, DE KD2XA
 

I am curious why you over couple the final?
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Vortex Joe - N3IBX
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« Reply #11 on: May 31, 2005, 04:18:00 PM »

Chris,
        Many thanks for sharing the HotWater 101 audio mods. I've heard your rig and thought it sounded definitely FBOM!

How difficult was it to modify the rx in the HW-101 for AM? I know of the Heathkit 3.75KC AM filter, but was wondering what else, if anything could be used. Any info will be appreciated.
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Joe Cro N3IBX

Anything that is Breadboarded,Black Crackle, or that squeals when you tune it gives me MAJOR WOOD!
rozradio
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« Reply #12 on: June 06, 2005, 06:45:38 PM »

Posted: Mon Jun 06, 2005 5:41 pm    Post subject: HW-100    

--------------------------------------------------------------------------------
 
I Gang:

me agn. I bin busy reworking the HW-100 C/Boards. What a mess, tube sockets with no Solder, cold joints, missing Components etc etc. The RF driver board was the worst. Removed the Diodes X4 from mod. board. All boards need a good cleaning. Can't believe it worked bk then, if it did at all.

Thanx agn for the help

Is there a way to add AM mode for RX..?

73... Richard/VA3VJC
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w3jn
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« Reply #13 on: June 06, 2005, 08:03:52 PM »

You could add a simple diode envelope detector.  However, the selectivity is gonna be terrible since you bypassed the crystal filter for AM use.  Best to use an external receiver.

73 John
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Steve - WB3HUZ
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« Reply #14 on: June 06, 2005, 08:04:49 PM »

Slightly overloading the final will make it run less efficiently. This produces less carrier, thus providing a little more headroom for the audio peaks.

Someone told me it can make some amps more linear. I've never verified this.


Quote from: Jim, W5JO
Quote from: KD2XA
to operate, switch to CW or TUNE, load for max power out, then increase the loading until the output drops about 5-10%. switch to LSB, set the carrier balance pot to give about 15-20W carrier, DE KD2XA
 

I am curious why you over couple the final?
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Jim, W5JO
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« Reply #15 on: June 06, 2005, 09:15:33 PM »

Quote from: Steve - WB3HUZ
Slightly overloading the final will make it run less efficiently. This produces less carrier, thus providing a little more headroom for the audio peaks.

Someone told me it can make some amps more linear. I've never verified this.
quote]

Well Steve, my understanding is that when tuning the final, you are matching one impedance to another.  Matching impedances gives maximum transfer of power.  Would not undercoupling give the same effect, just at a different load impedance on the final tube than overcoupling?

When under or over coupled the Q of the circuit is off as well and wouldn't you be more prone to harmonics?
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Steve - WB3HUZ
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« Reply #16 on: June 06, 2005, 09:25:33 PM »

Underloading won't yield the power needed on the positive audio peaks.

"Mistuning" by 5-10% won't mean diddly at 2x the frequency. And the Q may actually be higher. I've seen documentation for several BC rigs that recommend this type of tuning (although it actually resulted in more output not less).
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rozradio
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« Reply #17 on: June 09, 2005, 09:12:45 PM »

Hello Gentlmen:

I have a few RF. Finals sitting on the Shelf  807 1625 6GB6 6146 and so forth. I was thinking on home brewing a CW/AM low power ,  say 20 W..
I was thinking on 2E26 , a tiny version of 6146 for the Final. Has anyone had any dealings with these tubes and can pass on any spec.s or experiances with said tubes..

Thankyou    VA3VJC/Richard
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w3jn
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« Reply #18 on: June 10, 2005, 06:42:26 AM »

Richard - why don't you use that 1625 (a 12 volt 807) and build the series mudulated 50W rig described in the "Online Handbook" section.

73 John
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rozradio
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« Reply #19 on: June 10, 2005, 10:09:44 PM »

I noticed that the OA2 reg tube pulses with SSb peaks on my working HW-100 and goes out when I turn up the drive.. Is this a sure sign of P/Supply taking a dump.?.  doesn't take much  turning up for this to happen.

P/Supply is not a Heathkit unit, some sort of Homebrew thing

VA3VJC / Richard
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