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Author Topic: Heath Apache TX-1 bias adjustments  (Read 13800 times)
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KC2ZFA
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« Reply #25 on: May 25, 2020, 11:23:50 AM »

A mic jack in line, but behind, the key jack ?

The mic plug doubles as a deadly weapon ?
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« Reply #26 on: May 25, 2020, 04:24:58 PM »


...I don't get the connection between my running a phoenolic rod through the key jack ( so I can turn my tone control pot) and a long barreled Amphenol mic jack.

If it doesn't apply to your situation then be not concerned.

For the modification described on schematic 2 I had to use a long-barrel jack.

Phil
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Pete, WA2CWA
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« Reply #27 on: May 25, 2020, 04:48:25 PM »


...I don't get the connection between my running a phoenolic rod through the key jack ( so I can turn my tone control pot) and a long barreled Amphenol mic jack.
If it doesn't apply to your situation then be not concerned.

For the modification described on schematic 2 I had to use a long-barrel jack.
Phil

I already put it out of my mind.  Grin
In 60 years of owning and using this Apache and 59 years of owning the matching SB-10, my modifications have been minimal. I always liked the way the Apache operated even in its overall stock form although I did solid-state the power supplies back in the 70's. The tone control stuff wasn't meant to be permanent, but since it worked and didn't require much room or effort, I left it in.

I generally don't modify stuff unless I feel it's important to me or to the integrity of the equipment. If you Google "Heathkit Apache modifications, you'll get over 500K hits. That's funny!
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« Reply #28 on: May 25, 2020, 05:56:35 PM »

I too like the way the Apache operates, its tuning, etc.,  which seems to be more straightforward than the Ef Johnson's  which is why I have my EF Johnson Viking II-CDC up for sale.

However, the Apache's audio was in need of major improvement, such as removing the 470k loading resistor on the mic input which was ok for slopbucket audio but not good for D-104 AM audio. The ridiculous 510 pF coupling caps were also problematic for low end audio, again ok for slopbucket use but not for AM.

If you know how to use the mic gain properly and use a scope to monitor your AM output envelope, the Clipper circuitry is not needed and your audio will sound much better if it is removed. Again, this junk circuit is ok for slopbucket audio but not for AM.

Anyway, the other mods are contained in the schematics if anyone is so interested in improving their Apache.

Have a great Memorial Day. Gotta go check the grill.


Phil

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AG5UM
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« Reply #29 on: May 25, 2020, 07:08:15 PM »

It's nice to hear good comments on the TX-1 Apache, Do you also like the RX-1 Mohawk? I see you have the matching set,
I've never owned a RX-1, I'd be interested in your opinion of the RX-1? They make such a cool matching set.
Nice pictures.
AG5UM
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« Reply #30 on: May 25, 2020, 07:21:30 PM »

I too like the way the Apache operates, its tuning, etc.,  which seems to be more straightforward than the Ef Johnson's  which is why I have my EF Johnson Viking II-CDC up for sale.

However, the Apache's audio was in need of major improvement, such as removing the 470k loading resistor on the mic input which was ok for slopbucket audio but not good for D-104 AM audio. The ridiculous 510 pF coupling caps were also problematic for low end audio, again ok for slopbucket use but not for AM.

If you know how to use the mic gain properly and use a scope to monitor your AM output envelope, the Clipper circuitry is not needed and your audio will sound much better if it is removed. Again, this junk circuit is ok for slopbucket audio but not for AM.

Phil

Since I never really cared for the D-104, I don't use it on the Apache. So D-104 AM audio (whatever that is) is unimportant. I use an EV 664. Also, since I don't really have an interest in sounding like Hi-Fi audio, and since 75 or 40 meter conditions can really chew up audio anyway, wideband AM audio is unimportant to me. I also generally keep the receiver bandpass to 6 KHz or less depending on band conditions.
Sometimes I'll play during a SSB contest weekend with the Apache and SB-10 and use a D-104 with the SB-10. Making the contact is what's important and not the audio during these sessions.
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« Reply #31 on: May 25, 2020, 07:31:04 PM »

I also have an RX-1 Mohawk receiver. Took me plus 30 years after building the Apache to find one in great shape. It came from the original builder who became a silent key. The receiver is not bad on non crowded band conditions. I don't find the selectivity great and seem to spend a lot of time diddling with the IF Gain control on CW and SSB. It's not my primary boatanchor receiver. That's reserved for either the general coverage National HRO-500 or the amateur band coverage Squires Sanders SS-1R.
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AG5UM
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« Reply #32 on: May 25, 2020, 07:40:05 PM »

I bought two SB-10 units in nice condition for my DX-100, but I have'nt checked them out yet,
any comments from your experience with the SB-10??
I need to get mine up and going.Thanks for the comments on the RX-1.
Donnie
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Pete, WA2CWA
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« Reply #33 on: May 25, 2020, 08:46:12 PM »

SB-10 is a phase shifting SSB exciter. After 60 years I would suspect many of the components in the audio and RF phase shifting areas need to be checked for value and condition. There was a great CQ article on updating the SB-10 back in the 70's. CQ Magazine, May 1970, page 22. Both Null pots should be replaced to a minimum 5 turn type pot. I use 10 turn pots. If you don't, you'll spend a good portion of your operating diddling with the original pots trying to keep the sideband carrier suppression near zero.

Did you modify your DX-100 yet for the use of the SB-10?
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« Reply #34 on: May 25, 2020, 09:14:55 PM »

It's nice to hear good comments on the TX-1 Apache, Do you also like the RX-1 Mohawk? I see you have the matching set,
I've never owned a RX-1, I'd be interested in your opinion of the RX-1? They make such a cool matching set.
Nice pictures.
AG5UM


Hi Donnie,

I like it very much. I did do some minor circuit modifications. I have it on a Beverage antenna and when the conditions are crummy on my vertical I use the Mohawk.

My other two vintage receivers are the Hallicrafters S-108 and the Knight R-100.


Phil

* Simple Mohawk Modifications for AMphone.pdf (214.26 KB - downloaded 192 times.)
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AG5UM
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« Reply #35 on: May 25, 2020, 09:49:02 PM »

Thanks for the CQ article info. I'll try to look that up. Sounds good on the 10-turn pots,
sounds like the voice of experience, thanks.
No, I have not modified the DX-100 yet, but I do have the Heathkit manuals for the DX-100 and the SB-10 also.
so I do have the instructions at least.
The beverage antenna is something I've been wanting to play with also, I've got the room...
Well, maybe this will inspire me to get the SB-10's out and see what I can do with them,
Thanks for the info..
Donnie
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« Reply #36 on: May 26, 2020, 12:52:12 AM »

Thanks for the CQ article info. I'll try to look that up. Sounds good on the 10-turn pots,
sounds like the voice of experience, thanks.
No, I have not modified the DX-100 yet, but I do have the Heathkit manuals for the DX-100 and the SB-10 also.
so I do have the instructions at least.

Donnie
AG5UM

One of the common problems when using the DX-100 with the SB-10 on SSB, besides the inconvenience of connecting and disconnecting (mode switch is just for AM and CW), is the rather fragile and drifty VFO which requires almost constant diddling with the SB-10 controls. Many DX-100's also exhibit lower drive on 10 and 15 meters causing not enough SB-10 drive output. Personally, with two SB-10s, I would try to acquire an Apache and have all the necessary mods and switching already done for you.
It probably would be a lot less aggravation.
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« Reply #37 on: May 26, 2020, 11:51:34 AM »

Yes, the Apache TX-1 with the SB-10 adapter would make a fun SSB station, I could then just use the DX-100 for
AM and code, what it was designed for. Thanks for the advice.
AG5UM
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