Galaxy DX 2527 (EPT295013Z) Direct Injection Help

This topic is for posting general questions and answers related to the info found in the High Fidelity Audio section above to KEEP THAT FORUM CLEAN! Only instructions, diagrams and schematics will be posted in the above section. PLEASE POST All YOUR QUESTIONS AND ANSWERS RELATED TO MODS SHOWN IN THE HIGH FIDELITY AUDIO SECTION HERE!
User avatar
Goldfinger
Site Maintenance
Posts: 3016
Joined: Sat Jun 30, 2007 12:27 am
Location: Beaver State

Re: Galaxy DX 2527 (EPT295013Z) Direct Injection Help

Postby Goldfinger » Thu Jun 07, 2018 12:02 pm

I found it, it's inline between the mic amp IC and C299. It can be injected there for AM but you have to make C298 and C299 larger to allow the lows to pass. Injecting at C299 is a better choice for AM.

You have to inject at the junction of C136/R157 for wide SSB/ FM. That's where the audio from to mic amp splits off to AM and SSB/FM
C136.png
C136.png (34.39 KiB) Viewed 206 times
wwpdx
wwpdx.com
391redneckradio
WWPDX MEMBER
Posts: 8
Joined: Mon May 28, 2018 10:17 am
Location: Shenandoah Valley, Virginia

Re: Galaxy DX 2527 (EPT295013Z) Direct Injection Help

Postby 391redneckradio » Thu Jun 07, 2018 8:28 pm

I understand. So, the way I understand I would need 2 mono jacks, one for AM and one for SSB. I cant inject at one spot for both, correct? Thanks again.
User avatar
Goldfinger
Site Maintenance
Posts: 3016
Joined: Sat Jun 30, 2007 12:27 am
Location: Beaver State

Re: Galaxy DX 2527 (EPT295013Z) Direct Injection Help

Postby Goldfinger » Fri Jun 08, 2018 7:55 am

Yeah, probably so. You *might* be able to use one jack with a 4.7K isolation resistor between the jack and each injection point but to avoid any headache, separate jacks would be the way to go. It wouldn't *hurt* the radio to try the single jack with isolation resistors, you just might get some unwanted crosstalk if the radio doesn't switch off the unused mode circuits. (although looking at the schematic it looks like it does switch off the unused modes)
If you wanted to try, just use one isolation resistor and one blocking cap on each injection point feed coming from the jack.
I've never tried feeding all modes with a single jack so If you do try it and it works good, let us know!
If the 4.7K resistors make it hard to drive with line level, try lowering them to 2.2K. Half watt resistors are fine.
wwpdx
wwpdx.com
391redneckradio
WWPDX MEMBER
Posts: 8
Joined: Mon May 28, 2018 10:17 am
Location: Shenandoah Valley, Virginia

Re: Galaxy DX 2527 (EPT295013Z) Direct Injection Help

Postby 391redneckradio » Fri Jun 08, 2018 3:05 pm

Thanks for all your help. I just added another 1/4 mono jack for SSB so they wouldnt interfere with one another. I moved my AM inject to c299. Seems to work a lot better. Audio sounds very good. Thanks again for your knowledge! It is greatly appreciated! Take care and its all about our Lord and Saviour Jesus Christ!
User avatar
Goldfinger
Site Maintenance
Posts: 3016
Joined: Sat Jun 30, 2007 12:27 am
Location: Beaver State

Re: Galaxy DX 2527 (EPT295013Z) Direct Injection Help

Postby Goldfinger » Sat Jun 09, 2018 8:10 am

You are welcome.
If you would like to get rid of the roll off below 100hz on AM, change C301 from a 100uF to a 220uF - 16 volt observing polarity.
wwpdx
wwpdx.com
391redneckradio
WWPDX MEMBER
Posts: 8
Joined: Mon May 28, 2018 10:17 am
Location: Shenandoah Valley, Virginia

Re: Galaxy DX 2527 (EPT295013Z) Direct Injection Help

Postby 391redneckradio » Sat Jun 09, 2018 7:06 pm

Thanks again so much! I have another quick question about setting up an amp for SSB. I have not messed with it much. On AM I use a Dosy PM-1000-TS mostly for the modulation meter. Now I realize its a Dosy and everyone has there opinion about Dosy, Bird, etc. I set my carrier for 50 watt and set it to 100% mod and let it roll. Im not interested in big watts Im interested in audio quality. Im using an old RM KL500, 1446 box, which has SSB delay but people tell me it sounds over driven. I know there is no carrier on SSB so could you tell me how to set the radio to go with amp. My 2527 has had the NPC-RC mod done, Q32 and Q57 are still intact. I dont know if there is a trick that I dont know about. Thanks again.
User avatar
Goldfinger
Site Maintenance
Posts: 3016
Joined: Sat Jun 30, 2007 12:27 am
Location: Beaver State

Re: Galaxy DX 2527 (EPT295013Z) Direct Injection Help

Postby Goldfinger » Sun Jun 10, 2018 3:01 pm

The 1446 RM KL500 is supposed to have bias so it's probably not distorted from being class C. If you direct injected the SSB, it's bypassing Q32 so there wont be any ALC to limit the SSB mod.
You can check if it's the amp by getting a barefoot radio check to see if the distortion goes away. If the SSB is overmodulating, all you can do is lower the gain on the direct inject or use a brick-wall limiter in your mic chain to limit the SSB power to 2/3rds of max.
wwpdx
wwpdx.com
391redneckradio
WWPDX MEMBER
Posts: 8
Joined: Mon May 28, 2018 10:17 am
Location: Shenandoah Valley, Virginia

Re: Galaxy DX 2527 (EPT295013Z) Direct Injection Help

Postby 391redneckradio » Mon Jun 11, 2018 6:29 pm

Would to big of a cap make it sound distorted on SSB? I run a 10uf non-polarized electrolytic for AM and it does great but do you think I might be to much for SSB? I have some 2.2uf. Again Im not trying to be a pain but it sounds distorted without the amp.
User avatar
Goldfinger
Site Maintenance
Posts: 3016
Joined: Sat Jun 30, 2007 12:27 am
Location: Beaver State

Re: Galaxy DX 2527 (EPT295013Z) Direct Injection Help

Postby Goldfinger » Tue Jun 12, 2018 8:14 pm

Yeah, it's possible it's getting too much bass, the SSB filter may not like it.
I also looked again at the schematic and C131 needs to be higher in value to pass the lows on SSB.
wwpdx
wwpdx.com

Return to “>>> HIGH FIDELITY AUDIO Q and A <<< POST QUESTIONS AND COMMENTS HERE!”

Who is online

Users browsing this forum: No registered users and 0 guests